Change markings are relative to the Recommendation of 23 January 2007.
This document defines constructor functions, operators, and functions on the datatypes defined in
This is the third version of the specification of this function library. The first version was included as an intrinsic part of the
This is one document in a set of seven documents that are being progressed to Recommendation together (XQuery 3.0, XQueryX 3.0, XSLT 3.0, Data Model 3.0, Functions and Operators 3.0, Serialization 3.0, XPath 3.0).
W3C publishes a
This document was jointly developed by the W3C
Once the entrance criteria for Proposed Recommendation have been achieved,
the Director will be requested to advance this document to
This Candidate Recommendation makes
several substantive technical changes (as well as many
editorial changes), including new features, adopted since the Last Call Working Draft was published.
Please note that this Candidate Recommendation of XPath and XQuery Functions and Operators 3.0 represents the
second version of
This specification is designed to be referenced normatively from
other specifications defining a host language for it; it is not
intended to be implemented outside a host language. The
implementability of this specification has been tested in the context
of its normative inclusion in host languages defined by the
This document incorporates changes made against the
Please report errors in this document using W3C's
Publication as a Candidate Recommendation does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document was produced by groups operating under the
The purpose of this document is to catalog the functions and operators required for
XPath 3.0, XQuery 3.0 and XSLT 3.0. The exact syntax used to call these
functions and operators is specified in
This document defines constructor functions and functions that take typed values as
arguments. Some of the functions specify the semantics of operators defined in
xs:dateTimeStamp
, and it
incorporates as builtin types the two types xs:yearMonthDuration
and xs:dayTimeDuration
which were previously XDM additions to the type system. In addition, XSD 1.1 clarifies and updates many
aspects of the definitions of the existing data types: for example, it extends the value space of
xs:double
to allow both positive and negative zero, and extends the lexical space to allow +INF
;
it modifies the value space of xs:Name
to permit additional Unicode characters; it allows year zero and disallows leap seconds in xs:dateTime
values; and it allows any character string to appear as the value of an xs:anyURI
item.
Implementations of this specification
References to specific sections of some of the above documents are indicated by
crossdocument links in this document. Each such link consists of a pointer to a
specific section followed a superscript specifying the linked document. The
superscripts have the following meanings: 'XQ'
The Functions and Operators specification is intended primarily as a
component that can be used by other specifications. Therefore, Functions
and Operators relies on specifications that use it (such as
Authors of conformance criteria for the use of the Functions and Operators should pay particular attention to the following features:
It is
It is
Support for XML 1.0 and XML 1.1 by the datatypes used in Functions and Operators.
The XML Schema 1.1 recommendation
introduces one new concrete data type: xs:dateTimeStamp
; it also incorporates
the types xs:dayTimeDuration
, xs:yearMonthDuration
,
and xs:anyAtomicType
which were previously defined as part of xs:NCName
based on the rules in XML 1.1 rather than 1.0.
In this document, text labeled as an example or as a Note is provided for explanatory purposes and is not normative.
The functions and operators defined in this document are contained in one of
several namespaces (see xs:QName
.
This document uses conventional prefixes to refer to these namespaces. Userwritten
applications can choose a different prefix to refer to the namespace, so long as it is
bound to the correct URI. The host language may also define a default namespace for
function calls, in which case function names in that namespace need not be prefixed
at all. In many cases the default namespace will be
http://www.w3.org/2005/xpathfunctions
, allowing a call on the fn:name
function (for example) to be written as name()
rather than fn:name()
;
in this document, however, all example function calls are explicitly prefixed.
The URIs of the namespaces and the conventional prefixes associated with them are:
http://www.w3.org/2001/XMLSchema
for constructors —
associated with xs
.
The section http://www.w3.org/2001/XMLSchema
,
and are named in this document using the xs
prefix.
http://www.w3.org/2005/xpathfunctions
for functions — associated with fn
.
The namespace
prefix used in this document for most functions that are available to users is
fn
.
http://www.w3.org/2005/xpathfunctions/math
for functions — associated with math
.
This namespace is used for some mathematical functions. The namespace
prefix used in this document for these functions is math
.
These functions are available to users in exactly the same way as those in the
fn
namespace.
http://www.w3.org/2005/xqterrors
— associated with
err
.
There are no functions in this namespace; it is used for error codes.
This document uses the prefix err
to represent the namespace URI
http://www.w3.org/2005/xqterrors
, which is the namespace for all XPath
and XQuery error codes and messages. This namespace prefix is not predeclared and
its use in this document is not normative.
The namespace URI associated with the err
prefix is not
expected to change from one version of this document to another. The
contents of this namespace may be extended to allow additional errors to be returned.
http://www.w3.org/2010/xsltxqueryserialization
— associated with
output
.
There are no functions in this namespace: it is
used for serialization parameters, as described in
Functions defined with the op
prefix are described here to
underpin the definitions of the operators in op
prefix. For example, multiplication is generally
associated with the *
operator, but it is described as a function
in this document:
In general, the specifications named above do not support function overloading
in the sense that functions that have multiple signatures with the same name and
the same number of parameters are not supported. Consequently, there are no such
overloaded functions in this document except for legacy fn:string
, which accepts a single parameter of
a variety of types. In addition, it should be noted that the functions defined
in numeric
parameters accept arguments of type xs:integer
,
xs:decimal
, xs:float
or xs:double
. See
Each function is defined by specifying its signature, a description of the return type and each of the parameters and its semantics. For many functions, examples are included to illustrate their use.
Each function's signature is presented in a form like this:
In this notation, ()
"; otherwise, the name is followed by a parenthesized list of
parameter declarations, each declaration specifies the static type of the
parameter, in italics, and a descriptive, but nonnormative, name. If there are
two or more parameter declarations, they are separated by a comma. The returntype
One function, fn:concat
, has a variable number of arguments (two or more).
More strictly, there is an infinite set of functions having the name fn:concat
, with arity
ranging from 2 to infinity. For this special case, a single function signature is given, with an ellipsis
indicating an indefinite number of arguments.
In some cases the word
is used in function signatures as a shorthand to indicate the four
numeric types: numeric
xs:integer
, xs:decimal
,
xs:float
and xs:double
. For example, a function with
the signature:
represents the following four function signatures:
For most functions there is an initial paragraph describing what the function does followed by semantic rules. These rules are meant to be followed in the order that they appear in this document.
In some cases, the static type returned by a function depends on the type(s) of
its argument(s). These special functions are indicated by using
The function name is a QName
as defined in fn:timezonefromdateTime
.
Rules for passing parameters to operators are described in the relevant sections
of xs:untypedAtomic
and the empty sequence are specified in this section.
As is customary, the parameter type name indicates that the function or operator
accepts arguments of that type, or types derived from it, in that position. This
is called xs:anyURI
can be promoted to produce an argument
of the required type. (See
xs:integer
may be used
where xs:decimal
is expected.
xs:decimal
may be
promoted to xs:float
or xs:double
.
Promotion to xs:double
should be done directly, not via
xs:float
, to avoid loss of precision.
xs:anyURI
can be promoted to the
type xs:string
.
Some functions accept a single value or the empty sequence as an argument and
some may return a single value or the empty sequence. This is indicated in the
function signature by following the parameter or return type name with a
question mark: "?
", indicating that either a single value or the
empty sequence must appear. See below.
Note that this function signature is different from a signature in which the
parameter is omitted. See, for example, the two signatures
for fn:string
. In the first signature, the parameter is omitted
and the argument defaults to the context item, referred to as .
.
In the second signature, the argument must be present but may be the empty
sequence, written as ()
.
Some functions accept a sequence of zero or more values as an argument. This is
indicated by following the name of the type of the items in the sequence with
*
. The sequence may contain zero or more items of the named type.
For example, the function below accepts a sequence of xs:double
and
returns a xs:double
or the empty sequence.
The diagrams below show how nodes, function items, primitive simple types, and user defined types fit together into a type system. This type system comprises two distinct hierarchies that both include the primitive simple types. In the diagrams, connecting lines represent relationships between derived types and the types from which they are derived; the arrowheads point toward the type from which they are derived. The dashed line represents relationships not present in this diagram, but that appear in one of the other diagrams. Dotted lines represent additional relationships that follow an evident pattern. The information that appears in each diagram is recapitulated in tabular form.
The xs:IDREFS
, xs:NMTOKENS
, and
xs:ENTITIES
types and the userdefined list and union types
are special types in that these types are lists or unions
rather than types derived by extension or restriction.
The first diagram and its corresponding table illustrate
the relationship of various item types. Item types in the data model
form a lattice rather than a hierarchy: in the relationship defined
by the derivedfrom(A, B)
function, some types are derived
from more than one other type. Examples include functions (function(xs:string) as xs:int
is substitutable for function(xs:NCName) as xs:int
and also for
function(xs:string) as xs:decimal
), and union types (A
is substitutable for union(A, B)
and also for union(A, C)
.
In XDM, item types include node types, function types, and builtin atomic types.
The diagram, which shows only hierarchic relationships, is therefore a simplification of
the full model.
In the table, each type whose name is indented is derived from the type whose name appears nearest above it with one less level of indentation.
item  
xs:anyAtomicType  
function(*)  
function(item()*) as item()*  
function(item()*) as item()  
function(item()*) as item()?  
function(item()*, item()*) as item()*  
node  
attribute  
userdefined attribute types  
comment  
document  
userdefined document types  
element  
userdefined element types  
namespace  
processinginstruction  
text 
The next diagram and table illustrate the any type
type hierarchy, in which
all types are derived from distinguished type xs:anyType
.
In the table, each type whose name is indented is derived from the type whose name appears nearest above it with one less level of indentation.
xs:anyType  
userdefined complex types  
xs:untyped  
xs:anySimpleType  
userdefined list and union types  
xs:IDREFS  
xs:NMTOKENS  
xs:ENTITIES  
xs:anyAtomicType 
The final diagram and table show all of the atomic types, including the primitive simple types and the
builtin types derived from the primitive simple types.
This includes all the builtin datatypes defined in
In the table, each type whose name is indented is derived from the type whose name appears nearest above it with one less level of indentation.
xs:untypedAtomic  
xs:dateTime  
xs:dateTimeStamp  
xs:date  
xs:time  
xs:duration  
xs:yearMonthDuration  
xs:dayTimeDuration  
xs:float  
xs:double  
xs:decimal  
xs:integer  
xs:nonPositiveInteger  
xs:negativeInteger  
xs:long  
xs:int  
xs:short  
xs:byte  
xs:nonNegativeInteger  
xs:unsignedLong  
xs:unsignedInt  
xs:unsignedShort  
xs:unsignedByte  
xs:positiveInteger  
xs:gYearMonth  
xs:gYear  
xs:gMonthDay  
xs:gDay  
xs:gMonth  
xs:string  
xs:normalizedString  
xs:token  
xs:language  
xs:NMTOKEN  
xs:Name  
xs:NCName  
xs:ID  
xs:IDREF  
xs:ENTITY  
xs:boolean  
xs:base64Binary  
xs:hexBinary  
xs:anyURI  
xs:QName  
xs:NOTATION 
When XSD 1.1 is supported, one additional type needs to be added to these
diagrams: the type xs:dateTimeStamp
, which is derived from xs:dateTime
.
The terminology used to describe the functions and operators on
This document uses the terms string
, character
, and codepoint
with the following meanings:
This definition excludes Unicode characters in the surrogate blocks as well as xFFFE and xFFFF, while including characters with codepoints greater than xFFFF which some programming languages treat as two characters. The valid characters are defined by their codepoints, and include some whose codepoints have not been assigned by the Unicode consortium to any character.
xs:string
data type.
The set of codepoints is thus wider than the set of characters.
This specification spells "codepoint" as one word; the Unicode specification spells
it as "code point".
Equivalent terms found in other specifications are
"character number" or "code position". See
Because these terms appear so frequently, they are hyperlinked to the definition only when there is a particular desire to draw the reader's attention to the definition; the absence of a hyperlink does not mean that the term is being used in some other sense.
It is
Unless explicitly stated, the xs:string
values returned by the
functions in this document are not normalized in the sense of
In functions that involve character counting such
as fn:substring
, fn:stringlength
and
fn:translate
, what is counted is the number of XML
This document uses the phrase "namespace URI" to identify the concept identified
in
It also uses the term expandedQName
defined below.
xs:QName
. When this document
refers to xs:QName
we always mean the value space, i.e.
a namespace URI, local name pair (and not the lexical space
referring to constructs of the form prefix:localname).
The term URI is used as follows:
xs:anyURI
datatype
as defined in
Note that this means, in practice, that where this
specification requires a "URI Reference", an IRI as defined in xs:anyURI
is a wider definition than the definition in
A feature of this specification included to ensure that
implementations that use this feature remain compatible with
Conforming documents and processors are permitted to, but need not, behave as described.
Conforming documents and processors are required to behave as described; otherwise, they are either nonconformant or else in error.
Possibly differing between implementations, but specified and documented by the implementor for each particular implementation.
Possibly differing between implementations, but not specified by this or other W3C specification, and not required to be specified by the implementor for any particular implementation.
This section is concerned with the question of whether two calls on a function, with the same arguments, may produce different results.
The following definition explains more precisely what it means for two function calls to return the same result:
Both items are atomic values, of precisely the same type, and the values are equal as defined using the eq
operator,
using the Unicode codepoint collation when comparing strings
Both items are nodes, and represent the same node
Both items are function items, and have the same name (or absence of a name), arity, function signature, and closure. (Note that there is no function or operator defined in the specification that tests whether two function items are identical.)
Some functions produce results that depend not only on their explicit arguments, but also on the static and dynamic context.
A function that is contextdependent can be used as a named
function reference, can be partially applied, and can be found using fn:functionlookup
.
The principle in such cases is that the static context used for the function evaluation
is taken from the static context of the named function reference, partial function application, or the call
on fn:functionlookup
; and the dynamic context for the function evaluation is taken from the dynamic
context of the evaluation of the named function reference, partial function application, or the call
of fn:functionlookup
. In effect, the static and dynamic part of the context thus act
as part of the closure of the function item.
Contextdependent functions fall into a number of categories:
The functions fn:currentdate
, fn:currentdateTime
, fn:currenttime
, fn:implicittimezone
,
fn:adjustdatetotimezone
, fn:adjustdateTimetotimezone
, and
fn:adjusttimetotimezone
depend on properties of the dynamic context that are
fixed within the op:
namespace that manipulate dates and times and
that make use of the implicit timezone. These functions will return the same
result if called repeatedly during a single
A number of functions including fn:baseuri#0
, fn:data#0
,
fn:documenturi#0
, fn:position
, fn:last
, fn:id#1
,
fn:idref#1
, fn:elementwithid#1
, fn:lang#1
, fn:localname#0
,
fn:name#0
, fn:namespaceuri#0
, fn:normalizespace#0
, fn:number#0
,
fn:root#0
, fn:string#0
,
fn:stringlength#0
, and fn:path#0
depend on the focus. These functions will in general return
different results on different calls if the focus is different.
The function fn:defaultcollation
and many stringhandling operators and functions depend
on the default collation and the inscope collations, which are both properties
of the static context. If a particular call of one of these functions is
evaluated twice with the same arguments then it will return the same result
each time (because the static context, by definition, does not change at run
time). However, two distinct calls (that is, two calls on the function
appearing in different places in the source code) may produce different results
even if the explicit arguments are the same.
Functions such as fn:staticbaseuri
, fn:doc
, and fn:collection
depend on
other aspects of the static context. As with functions that depend on
collations, a single call will produce the same results on each call if the
explicit arguments are the same, but two calls appearing in different places in
the source code may produce different results.
The fn:functionlookup
function is a special case because it is
potentially dependent on everything in the static and dynamic context. This is because the static and dynamic
context of the call to fn:functionlookup
are used as the static and dynamic context of the
function that fn:functionlookup
returns.
All functions defined in this specification are
Some functions (such as fn:distinctvalues
and fn:unordered
) produce results in an
The function fn:analyzestring
constructs an element node to
represent its results. There is no guarantee that repeated calls with the same
arguments will return the same identical node (in the sense of the is
operator). However, if nonidentical nodes are returned, their content will be the
same in the sense of the fn:deepequal
function. Such a function is said
to be
Some functions (such as fn:doc
and fn:collection
) create new nodes by reading external
documents. Such functions are guaranteed to be
Where the results of a function are described as being (to a greater or lesser
extent)
Accessors and their semantics are described in
Function  Accessor  Accepts  Returns 

fn:nodename

nodename
 an optional node  zero or one xs:QName

fn:nilled

nilled
 a node  an optional xs:boolean

fn:string

stringvalue
 an optional item or no argument 
xs:string

fn:data

typedvalue
 zero or more items  a sequence of atomic values 
fn:baseuri

baseuri
 an optional node or no argument  zero or one xs:anyURI

fn:documenturi

documenturi
 an optional node  zero or one xs:anyURI

Returns the name of a node, as an xs:QName
.
The zeroargument form of this function is
The oneargument form of this function is
If the argument is omitted, it defaults to the context item
(.
). The behavior of the function if the argument is omitted is exactly
the same as if the context item had been passed as the argument.
If $arg
is the empty sequence, the empty sequence is returned.
Otherwise, the function returns the result of the dm:nodename
accessor as
defined in
The following errors may be raised when $arg
is omitted: if the context
item is
For element and attribute nodes, the name of the node is returned as an
xs:QName
, retaining the prefix, namespace URI, and local part.
For processing instructions, the name of the node is returned as an
xs:QName
in which the prefix and namespace URI are
For a namespace node, the function returns an empty sequence if the node represents the
default namespace; otherwise it returns an xs:QName
in which prefix and
namespace URI are
For all other kinds of node, the function returns the empty sequence.
Returns true for an element that is
The zeroargument form of this function is
The oneargument form of this function is
If the argument is omitted, it defaults to the context item (.
). The
behavior of the function if the argument is omitted is exactly the same as if the
context item had been passed as the argument.
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise the function returns the result of the dm:nilled
accessor as
defined in
The following errors may be raised when $arg
is omitted: if the context
item is
If $arg
is not an element node, the function returns the empty
sequence.
If $arg
is an untyped element node, the function returns false.
In practice, the function returns true
only for an element node that has
the attribute xsi:nil="true"
and that is successfully validated against a
schema that defines the element to be nillable; the detailed rules, however, are defined
in
Returns the value of $arg
represented as an
xs:string
.
The zeroargument form of this function is
The oneargument form of this function is
In the zeroargument version of the function, $arg
defaults to the context
item. That is, calling fn:string()
is equivalent to calling
fn:string(.)
.
If $arg
is the empty sequence, the function returns the zerolength
string.
If $arg
is a node, the function returns the stringvalue of the node, as
obtained using the dm:stringvalue
accessor defined in
If $arg
is an atomic value, the function returns the result of the
expression $arg cast as xs:string
(see
A
A $arg
is a function item.
The expression string(23)
returns "23"
.
The expression string(false())
returns "false"
.
The expression string("Paris")
returns "Paris"
.
The expression string(abs#1)
raises error FOTY0014
.
let $para
:=
The expression string($para)
returns "In a hole in the ground there lived a hobbit."
.
Returns the result of atomizing a sequence, that is, replacing all nodes in the sequence by their typed values.
The zeroargument form of this function is
The oneargument form of this function is
If the argument is omitted, it defaults to the context item
(.
). The behavior of the function if the argument is omitted is exactly
the same as if the context item had been passed as the argument.
The result of fn:data
is the sequence of atomic values produced by
applying the following rules to each item in $arg
:
If the item is an atomic value, it is appended to the result sequence.
If the item is a node, the typed value of the node is appended to the result
sequence. The typed value is a sequence of zero or more atomic values:
specifically, the result of the dm:typedvalue
accessor as defined in
A $arg
is a node that does not have a typed value.
A $arg
is a function item.
The following $arg
is omitted:
if the context item is
The process of applying the fn:data
function to a sequence is referred to
as atomization
. In many cases an explicit call on fn:data
is
not required, because atomization is invoked implicitly when a node or sequence of nodes
is supplied in a context where an atomic value or sequence of atomic values is
required.
The expression data(123)
returns 123
.
let $para
:=
The expression data($para)
returns xs:untypedAtomic("In a hole in the ground there lived a hobbit.")
.
The expression data($para/term/@author)
returns xs:untypedAtomic("Tolkein")
.
The expression data(abs#1)
raises error FOTY0013
.
Returns the base URI of a node.
The zeroargument form of this function is
The oneargument form of this function is
The zeroargument version of the function returns the base URI of the
context node: it is equivalent to calling fn:baseuri(.)
. This may result
in an error being raised: if the context item is
The singleargument version of the function behaves as follows:
$arg
is the empty sequence, the function returns the empty
sequence.dm:baseuri
accessor
applied to the node $arg
. This accessor is defined, for each kind of
node, in the XDM specification (See See also fn:staticbaseuri
.
If $arg
is not specified, the following errors may be raised: if the
context item is
Returns the URI of a resource where a document can be found, if available.
The zeroargument form of this function is
The oneargument form of this function is
If the argument is omitted, it defaults to the context item
(.
). The behavior of the function if the argument is omitted is exactly
the same as if the context item had been passed as the argument.
If $arg
is the empty sequence, the function returns the empty sequence.
If $arg
is not a document node, the function returns the empty
sequence.
Otherwise, the function returns the value of the documenturi
accessor
applied to $arg
, as defined in
The following errors may be raised when $arg
is omitted: if the context
item is
In the case of a document node $D
returned by the fn:doc
function, or a document node at the root of a tree containing a node returned by the
fn:collection
function, it will always be true that either
fn:documenturi($D)
returns the empty sequence, or that the following
expression is true: fn:doc(fn:documenturi($D))
is $D
. It is
In this document, as well as in an error is raised
is used. Raising an error is equivalent to calling the fn:error
function defined in this section with the provided error code.
The above phrase is normally accompanied by specification of a specific error, to
wit: an error is raised [
. Each error defined
in this document is identified by an xs:QName
that is in the
http://www.w3.org/2005/xqterrors
namespace, represented in this document by the err
prefix. It is this
xs:QName
that is actually passed as an argument to the
fn:error
function. Calling this function raises an error. For a
more detailed treatment of error handing, see
The fn:error
function is a general function that may be called as above
but may also be called from xs:QName
argument.
Calling the fn:error
function raises an applicationdefined
error.
This function is
This function never returns a value. Instead it always raises an error. The effect of the error is identical to the effect of dynamic errors raised implicitly, for example when an incorrect argument is supplied to a function.
The parameters to the fn:error
function supply information that is
associated with the error condition and that is made available to a caller that asks for
information about the error. The error may be caught either by the host language (using
a try/catch construct in XSLT or XQuery, for example), or by the calling application or
external processing environment. The way in which error information is returned to the
external processing environment is
If fn:error
is called with no arguments, then its behavior is the same as
the function call:
If $code
is the empty sequence then the effective value is the
xs:QName
constructed by:
There are three pieces of information that may be associated with an error:
The $code
is an error code that distinguishes this error from others.
It is an xs:QName
; the namespace URI conventionally identifies the
component, subsystem, or authority responsible for defining the meaning of the
error code, while the local part identifies the specific error condition. The
namespace URI http://www.w3.org/2005/xqterrors
is used for errors
defined in this specification; other namespace URIs may be used for errors defined
by the application.
If the external processing environment expects the error code to be returned as a
URI or a string rather than as an xs:QName
, then an error code with
namespace URI NS
and local part LP
will be returned in
the form NS#LP
. The namespace URI part of the error code should
therefore not include a fragment identifier.
The $description
is a naturallanguage description of the error
condition.
The $errorobject
is an arbitrary value used to convey additional
information about the error, and may be used in any way the application
chooses.
This function always raises a
The value of the $description
parameter may need to be localized.
The type none
is a special type defined in
Any QName may be used as an error code; there are no reserved names or namespaces. The error is always classified as a dynamic error, even if the error code used is one that is normally used for static errors or type errors.
The expression fn:error()
raises error FOER0000
. http://www.w3.org/2005/xqterrors#FOER0000
(or the corresponding
xs:QName
) to the external processing environment, unless the error is
caught using a try/catch construct in the host language.).
The expression fn:error(fn:QName('http://www.example.com/HR', 'myerr:toohighsal'), 'Does not
apply because salary is too high')
raises error myerr:toohighsal
. http://www.example.com/HR#toohighsal
and the xs:string
"Does not apply because salary is too high"
(or the corresponding
xs:QName
) to the external processing environment, unless the error is
caught using a try/catch construct in the host language.).
Provides an execution trace intended to be used in debugging queries.
This function is
The function returns the value of $value
, unchanged.
In addition, the values of $value
, converted to an xs:string
,
and $label
fn:trace
function is
Consider a situation in which a user wants to investigate the actual value passed to
a function. Assume that in a particular execution, $v
is an
xs:decimal
with value 124.84
. Writing fn:trace($v,
'the value of $v is:')
will put the strings "124.84"
and
"the value of $v is:"
in the trace data set in implementation
dependent order.
This section specifies arithmetic operators on the numeric datatypes defined in
The operators described in this section are defined on the following numeric types. Each type whose name is indented is derived from the type whose name appears nearest above with one less level of indentation.
xs:decimal  
xs:integer  
xs:float  
xs:double 
They also apply to types derived by restriction from the above types.
This specification uses xs:float
and xs:double
values.
NaN
(nota number), which
has the unusual property that it is not equal to itself. Another consequence is that some operations return the value negative zero.NaN
as being equal to itself and defines only a single zero in the value space.
The text accompanying several functions defines behavior for both positive and negative zero inputs and outputs
in the interest of alignment with 0.0e0
(which is actually a unary minus operator
applied to an xs:double
value) will always return negative zero: see 0
XML Schema 1.1 introduces support for positive and negative zero as distinct values, and also uses the NaN
.
The following functions define the semantics of arithmetic operators defined in
Operators  Meaning 

op:numericadd
 Addition 
op:numericsubtract
 Subtraction 
op:numericmultiply
 Multiplication 
op:numericdivide
 Division 
op:numericintegerdivide
 Integer division 
op:numericmod
 Modulus 
op:numericunaryplus
 Unary plus 
op:numericunaryminus
 Unary minus (negation) 
The parameters and return types for the above operators are the basic numeric
types: xs:integer
, xs:decimal
, xs:float
and xs:double
, and types derived from them. The word
in function signatures signifies these four types. For simplicity, each
operator is defined to operate on operands of the same type and return the same
type. The exceptions are numeric
op:numericdivide
, which returns
an xs:decimal
if called with two xs:integer
operands
and op:numericintegerdivide
which always returns an xs:integer
.
If the two operands are not of the same type,
The result type of operations depends on their argument datatypes and is defined in the following table:
Operator  Returns 

op:operation(xs:integer, xs:integer)

xs:integer (except for op:numericdivide(integer,
integer) , which returns xs:decimal ) 
op:operation(xs:decimal, xs:decimal)

xs:decimal

op:operation(xs:float, xs:float)

xs:float

op:operation(xs:double, xs:double)

xs:double

op:operation(xs:integer)

xs:integer

op:operation(xs:decimal)

xs:decimal

op:operation(xs:float)

xs:float

op:operation(xs:double)

xs:double

These rules define any operation on any pair of arithmetic types. Consider the following example:
For this operation, xs:int
must be converted to
xs:double
. This can be done, since by the rules above:
xs:int
can be substituted for xs:integer
,
xs:integer
can be substituted for xs:decimal
,
xs:decimal
can be promoted to xs:double
. As far as possible, the promotions should be done in a
single step. Specifically, when an xs:decimal
is promoted to an
xs:double
, it should not be converted to an xs:float
and then to xs:double
, as this risks loss of precision.
As another example, a user may define height
as a derived type of
xs:integer
with a minimum value of 20 and a maximum value of 100.
He may then derive fenceHeight
using an enumeration to restrict the
permitted set of values to, say, 36, 48 and 60.
fenceHeight
can be substituted for its base type
height
and height
can be substituted for its base type
xs:integer
.
The basic rules for addition, subtraction, and multiplication
of ordinary numbers are not set out in this specification; they are taken as given. In the case of xs:double
and xs:float
the rules are as defined in NaN
,
and exception conditions such as overflow and underflow, are described more explicitly since they are not necessarily obvious.
On overflow and underflow situations during arithmetic operations conforming
implementations
For xs:float
and xs:double
operations, overflow
behavior
Raising a
Returning INF
or INF
.
Returning the largest (positive or negative) noninfinite number.
For xs:float
and xs:double
operations,
underflow behavior
Raising a
Returning 0.0E0
or +/ 2**Emin
or a
denormalized value; where Emin
is the smallest
possible xs:float
or xs:double
exponent.
For xs:decimal
operations, overflow behavior 0.0
must be returned.
For xs:integer
operations, implementations that support
limitedprecision integer operations
They
They
The functions op:numericadd
, op:numericsubtract
,
op:numericmultiply
, op:numericdivide
,
op:numericintegerdivide
and op:numericmod
are each
defined for pairs of numeric operands, each of which has the same
type:xs:integer
, xs:decimal
, xs:float
, or
xs:double
. The functions op:numericunaryplus
and
op:numericunaryminus
are defined for a single operand whose type
is one of those same numeric types.
For xs:float
and xs:double
arguments, if either
argument is NaN
, the result is NaN
.
For xs:decimal
values the number of digits of precision returned by
the numeric operators is
The divideByZero
and invalidOperation
. The
IEEE divideByZero
exception is raised not only by a direct attempt to divide by zero, but also by
operations such as log(0)
. The IEEE invalidOperation
exception is raised by
attempts to call a function with an argument that is outside the function's domain (for example,
sqrt(1)
or log(1)
. These IEEE exceptions do not cause a dynamic error
at the application level; rather they result in the relevant function or operator returning
NaN
. The underlying IEEE exception NaN
with no error.
The xs:float
and xs:double
each include only a single
NaN
value. This does not prevent the implementation distinguishing them internally,
and triggering different
Returns the arithmetic sum of its operands: ($arg1 + $arg2
).
Defines the semantics of the "+" operator applied to numeric values
General rules: see
For xs:float
or xs:double
values, if one of the operands is a
zero or a finite number and the other is INF
or INF
,
INF
or INF
is returned. If both operands are
INF
, INF
is returned. If both operands are
INF
, INF
is returned. If one of the operands is
INF
and the other is INF
, NaN
is
returned.
Returns the arithmetic difference of its operands: ($arg1 
$arg2
).
Defines the semantics of the "" operator applied to numeric values.
General rules: see
For xs:float
or xs:double
values, if one of the operands is a
zero or a finite number and the other is INF
or INF
, an
infinity of the appropriate sign is returned. If both operands are INF
or
INF
, NaN
is returned. If one of the operands is
INF
and the other is INF
, an infinity of the appropriate
sign is returned.
Returns the arithmetic product of its operands: ($arg1 *
$arg2
).
Defines the semantics of the "*" operator applied to numeric values.
General rules: see
For xs:float
or xs:double
values, if one of the operands is a
zero and the other is an infinity, NaN
is returned. If one of the operands
is a nonzero number and the other is an infinity, an infinity with the appropriate sign
is returned.
Returns the arithmetic quotient of its operands: ($arg1 div
$arg2
).
Defines the semantics of the "div" operator applied to numeric values.
General rules: see
As a special case, if the types of both $arg1
and $arg2
are
xs:integer
, then the return type is xs:decimal
.
A xs:decimal
and
xs:integer
operands, if the divisor is (positive or negative) zero.
For xs:float
and xs:double
operands, floating point division
is performed as specified in INF
. A negative number divided by positive zero
returns INF
. Division by negative zero returns INF
and
INF
, respectively. Positive or negative zero divided by positive or
negative zero returns NaN
. Also, INF
or INF
divided by INF
or INF
returns NaN
.
Performs an integer division.
Defines the semantics of the "idiv" operator applied to numeric values.
General rules: see
If $arg2
is INF
or INF
,
and $arg1
is not INF
or INF
, then the result is zero.
Otherwise, subject to limits of precision and overflow/underflow
conditions, the result is the largest (furthest from zero) xs:integer
value
$N
such that fn:abs($N * $arg2) le fn:abs($arg1) and fn:compare($N
* $arg2, 0) eq fn:compare($arg1, 0)
.
The second term in this condition ensures that the result has the correct sign.
The implementation may adopt a different algorithm provided that
it is equivalent to this formulation in all cases where xs:decimal
division.
A
A NaN
or if $arg1
is INF
or
INF
.
Except in situations involving errors, loss of precision, or overflow/underflow, the
result of $a idiv $b
is the same as ($a div $b) cast as
xs:integer
.
The semantics of this function are different from integer division as defined in programming languages such as Java and C++.
The expression op:numericintegerdivide(10,3)
returns 3
.
The expression op:numericintegerdivide(3,2)
returns 1
.
The expression op:numericintegerdivide(3,2)
returns 1
.
The expression op:numericintegerdivide(3,2)
returns 1
.
The expression op:numericintegerdivide(9.0,3)
returns 3
.
The expression op:numericintegerdivide(3.5,3)
returns 1
.
The expression op:numericintegerdivide(3.0,4)
returns 0
.
The expression op:numericintegerdivide(3.1E1,6)
returns 5
.
The expression op:numericintegerdivide(3.1E1,7)
returns 4
.
Returns the remainder resulting from dividing $arg1
, the dividend,
by $arg2
, the divisor.
Defines the semantics of the "mod" operator applied to numeric values.
General rules: see
The operation a mod b
for operands that are xs:integer
or
xs:decimal
, or types derived from them, produces a result such that
(a idiv b)*b+(a mod b)
is equal to a
and the magnitude of
the result is always less than the magnitude of b
. This identity holds even
in the special case that the dividend is the negative integer of largest possible
magnitude for its type and the divisor is 1 (the remainder is 0). It follows from this
rule that the sign of the result is the sign of the dividend.
For xs:float
and xs:double
operands the following rules
apply:
If either operand is NaN
, the result is NaN
.
If the dividend is positive or negative infinity, or the divisor is positive or
negative zero (0), or both, the result is NaN
.
If the dividend is finite and the divisor is an infinity, the result equals the dividend.
If the dividend is positive or negative zero and the divisor is finite, the result is the same as the dividend.
In the remaining cases, where neither positive or negative infinity, nor positive
or negative zero, nor NaN
is involved, the result obeys (a idiv
b)*b+(a mod b)
= a
.
Division is truncating division, analogous to integer division, not
A xs:integer
and
xs:decimal
operands, if $arg2
is zero.
The expression op:numericmod(10,3)
returns 1
.
The expression op:numericmod(6,2)
returns 0
.
The expression op:numericmod(4.5,1.2)
returns 0.9
.
The expression op:numericmod(1.23E2, 0.6E1)
returns 3.0E0
.
Returns its operand with the sign unchanged: (+
$arg
).
Defines the semantics of the unary "+" operator applied to numeric values.
General rules: see
The returned value is equal to $arg
, and is an
instance of xs:integer
, xs:decimal
, xs:double
, or
xs:float
depending on the type of $arg
.
Because function conversion rules are applied in the normal way, the unary +
can be used to force conversion of an untyped node to a number: the result of +@price
is the same as xs:double(@price)
if the type of @price
is
xs:untypedAtomic
.
Returns its operand with the sign reversed: (
$arg
).
Defines the semantics of the unary "" operator applied to numeric values.
General rules: see
The returned value is an instance of xs:integer
,
xs:decimal
, xs:double
, or xs:float
depending
on the type of $arg
.
For xs:integer
and xs:decimal
arguments, 0
and
0.0
return 0
and 0.0
, respectively. For
xs:float
and xs:double
arguments, NaN
returns
NaN
, 0.0E0
returns 0.0E0
and vice versa.
INF
returns INF
. INF
returns
INF
.
This specification defines the following comparison operators on numeric values.
Comparisons take two arguments of the same type. If the arguments are of
different types, one argument is promoted to the type of the other as described
above in NaN
, false
is
returned.
Function  Meaning 

op:numericequal  Returns true if and only if the value of $arg1 is equal to the
value of $arg2 . 
op:numericlessthan  Returns true if and only if $arg1 is numerically less
than $arg2 . 
op:numericgreaterthan  Returns true if and only if $arg1 is numerically
greater than $arg2 . 
Returns true if and only if the value of $arg1
is equal to the
value of $arg2
.
Defines the semantics of the "eq" operator on numeric values, and is also used in defining the semantics of "ne", "le" and "ge".
General rules: see
For xs:float
and xs:double
values, positive zero and negative
zero compare equal. INF
equals INF
, and INF
equals INF
. NaN
does not equal itself.
Returns true
if and only if $arg1
is numerically less
than $arg2
.
Defines the semantics of the "lt" operator on numeric values, and is also used in defining the semantics of "le".
General rules: see
For xs:float
and xs:double
values, positive infinity is
greater than all other nonNaN
values; negative infinity is less than all
other nonNaN
values. If $arg1
or $arg2
is
NaN
, the function returns false
.
Returns true
if and only if $arg1
is numerically
greater than $arg2
.
Defines the semantics of the "gt" operator on numeric values, and is also used in defining the semantics of "ge".
The function call op:numericgreaterthan($A, $B)
is defined to return the
same result as op:numericlessthan($B, $A)
The following functions are defined on numeric types. Each function returns a value of the same type as the type of its argument.
If the argument is the empty sequence, the empty sequence is returned.
For xs:float
and xs:double
arguments, if the
argument is "NaN", "NaN" is returned.
Except for fn:abs
, for xs:float
and
xs:double
arguments, if the argument is positive or
negative infinity, positive or negative infinity is returned.
Function  Meaning 

fn:abs  Returns the absolute value of $arg . 
fn:ceiling  Rounds $arg upwards to a whole number. 
fn:floor  Rounds $arg downwards to a whole number. 
fn:round  Rounds a value to a specified number of decimal places, rounding upwards if two such values are equally near. 
fn:roundhalftoeven  Rounds a value to a specified number of decimal places, rounding to make the last digit even if two such values are equally near. 
fn:round
and fn:roundhalftoeven
produce the same result in all cases
except when the argument is exactly midway between two values with the required precision.
Other ways of rounding midway values can be achieved as follows:
Towards negative infinity: fn:round($x)
Away from zero: fn:round(fn:abs($x))*fn:compare($x,0)
Towards zero: fn:abs(fn:round($x))*fn:compare($x,0)
Returns the absolute value of $arg
.
This function is
General rules: see
If $arg
is negative the function returns $arg
, otherwise it
returns $arg
.
If the type of $arg
is one of the four numeric types xs:float
,
xs:double
, xs:decimal
or xs:integer
the type
of the result is the same as the type of $arg
. If the type of
$arg
is a type derived from one of the numeric types, the result is an
instance of the base numeric type.
For xs:float
and xs:double
arguments, if the argument is
positive zero or negative zero, then positive zero is returned. If the argument is
positive or negative infinity, positive infinity is returned.
For detailed type semantics, see [Formal Semantics].
The expression fn:abs(10.5)
returns 10.5
.
The expression fn:abs(10.5)
returns 10.5
.
Rounds $arg
upwards to a whole number.
This function is
General rules: see
The function returns the smallest (closest to negative infinity) number with no
fractional part that is not less than the value of $arg
.
If the type of $arg
is one of the four numeric types xs:float
,
xs:double
, xs:decimal
or xs:integer
the type
of the result is the same as the type of $arg
. If the type of
$arg
is a type derived from one of the numeric types, the result is an
instance of the base numeric type.
For xs:float
and xs:double
arguments, if the argument is
positive zero, then positive zero is returned. If the argument is negative zero, then
negative zero is returned. If the argument is less than zero and greater than 1,
negative zero is returned.
For detailed type semantics, see [Formal Semantics].
The expression fn:ceiling(10.5)
returns 11
.
The expression fn:ceiling(10.5)
returns 10
.
Rounds $arg
downwards to a whole number.
This function is
General rules: see
The function returns the largest (closest to positive infinity) number with no
fractional part that is not greater than the value of $arg
.
If the type of $arg
is one of the four numeric types xs:float
,
xs:double
, xs:decimal
or xs:integer
the type
of the result is the same as the type of $arg
. If the type of
$arg
is a type derived from one of the numeric types, the result is an
instance of the base numeric type.
For xs:float
and xs:double
arguments, if the argument is
positive zero, then positive zero is returned. If the argument is negative zero, then
negative zero is returned.
For detailed type semantics, see [Formal Semantics].
The expression fn:floor(10.5)
returns 10
.
The expression fn:floor(10.5)
returns 11
.
Rounds a value to a specified number of decimal places, rounding upwards if two such values are equally near.
This function is
General rules: see
The function returns the nearest (that is, numerically closest) value to
$arg
that is a multiple of ten to the power of minus
$precision
. If two such values are equally near (for example, if the
fractional part in $arg
is exactly .5), the function returns the one that
is closest to positive infinity.
If the type of $arg
is one of the four numeric types xs:float
,
xs:double
, xs:decimal
or xs:integer
the type
of the result is the same as the type of $arg
. If the type of
$arg
is a type derived from one of the numeric types, the result is an
instance of the base numeric type.
The singleargument version of this function produces the same result as the
twoargument version with $precision=0
(that is, it rounds to a whole
number).
When $arg
is of type xs:float
and xs:double
:
If $arg
is NaN, positive or negative zero, or positive or negative
infinity, then the result is the same as the argument.
For other values, the argument is cast to xs:decimal
using an
implementation of xs:decimal
that imposes no limits on the number of
digits that can be represented. The function is applied to this
xs:decimal
value, and the resulting xs:decimal
is
cast back to xs:float
or xs:double
as appropriate to
form the function result. If the resulting xs:decimal
value is zero,
then positive or negative zero is returned according to the sign of
$arg
.
For detailed type semantics, see [Formal Semantics].
This function is typically used with a nonzero $precision
in financial
applications where the argument is of type xs:decimal
. For arguments of
type xs:float
and xs:double
the results may be
counterintuitive. For example, consider round(35.425e0, 2)
. The result is
not 35.43, as might be expected, but 35.42. This is because the xs:double
written as 35.425e0
has an exact value equal to 35.42499999999..., which is closer
to 35.42 than to 35.43.
The expression fn:round(2.5)
returns 3.0
.
The expression fn:round(2.4999)
returns 2.0
.
The expression fn:round(2.5)
returns 2.0
. 3
).
The expression fn:round(1.125, 2)
returns 1.13
.
The expression fn:round(8452, 2)
returns 8500
.
The expression fn:round(3.1415e0, 2)
returns 3.14e0
.
Rounds a value to a specified number of decimal places, rounding to make the last digit even if two such values are equally near.
This function is
General rules: see
The function returns the nearest (that is, numerically closest) value to
$arg
that is a multiple of ten to the power of minus
$precision
. If two such values are equally near (e.g. if the fractional
part in $arg
is exactly .500...), the function returns the one whose least
significant digit is even.
If the type of $arg
is one of the four numeric types xs:float
,
xs:double
, xs:decimal
or xs:integer
the type
of the result is the same as the type of $arg
. If the type of
$arg
is a type derived from one of the numeric types, the result is an
instance of the base numeric type.
The first signature of this function produces the same result as the second signature
with $precision=0
.
For arguments of type xs:float
and xs:double
:
If the argument is NaN
, positive or negative zero, or positive or
negative infinity, then the result is the same as the argument.
In all other cases, the argument is cast to xs:decimal
xs:decimal
value, and the resulting
xs:decimal
is cast back to xs:float
or
xs:double
as appropriate to form the function result. If the
resulting xs:decimal
value is zero, then positive or negative zero is
returned according to the sign of the original argument.
For detailed type semantics, see [Formal Semantics].
This function is typically used in financial applications where the
argument is of type xs:decimal
. For arguments of type xs:float
and xs:double
the results may be counterintuitive. For example, consider
roundhalftoeven(xs:float(150.015), 2)
. The result is not 150.02 as
might be expected, but 150.01. This is because the conversion of the
xs:float
value represented by the literal 150.015 to an
xs:decimal
produces the xs:decimal
value 150.014999389...,
which is closer to 150.01 than to 150.02.
The expression fn:roundhalftoeven(0.5)
returns 0.0
.
The expression fn:roundhalftoeven(1.5)
returns 2.0
.
The expression fn:roundhalftoeven(2.5)
returns 2.0
.
The expression fn:roundhalftoeven(3.567812e+3, 2)
returns 3567.81e0
.
The expression fn:roundhalftoeven(4.7564e3, 2)
returns 0.0e0
.
The expression fn:roundhalftoeven(35612.25, 2)
returns 35600
.
It is possible to convert strings to values of type xs:integer
,
xs:float
, xs:decimal
, or xs:double
using the constructor functions described in cast
expressions as described in
In addition the fn:number
function is available to convert strings
to values of type xs:double
. It differs from the xs:double
constructor function in that any value outside the lexical space of the xs:double
datatype is converted to the xs:double
value NaN
.
Returns the value indicated by $arg
or, if $arg
is
not specified, the context item after atomization, converted to an
xs:double
.
The zeroargument form of this function is
The oneargument form of this function is
Calling the zeroargument version of the function is defined to give the same result as
calling the singleargument version with the context item (.
). That is,
fn:number()
is equivalent to fn:number(.)
, as
defined by the rules that follow.
If $arg
is the empty sequence or if $arg
xs:double
, the xs:double
value
NaN
is returned.
Otherwise, $arg
xs:double
following the rules of xs:double
fails, the xs:double
value
NaN
is returned.
An error is raised $arg
is omitted and the context item is
As a consequence of the rules given above, a type error also occurs if the context item cannot be atomized, or if the result of atomizing the context item is a sequence containing more than one atomic value.
XSD 1.1 allows the string +INF
as a representation of positive infinity;
XSD 1.0 does not. It is
Generally fn:number
returns NaN
rather than raising a dynamic
error if the argument cannot be converted to xs:double
.
However, a type error is raised in the usual way if the supplied argument cannot be
atomized or if the result of atomization does not match the required argument type.
The expression fn:number($item1/quantity)
returns 5.0e0
.
The expression fn:number($item2/description)
returns xs:double('NaN')
.
Assume that the context item is the xs:string
value "15
".
Then fn:number()
returns 1.5e1
.
Formats an integer according to a given picture string, using the conventions of a given natural language if specified.
The twoargument form of this function is
The threeargument form of this function is
If $value
is an empty sequence, the function returns a zerolength
string.
In all other cases, the $picture
argument describes the format in which
$value
is output.
The rules that follow describe how nonnegative numbers are output. If the value of
$value
is negative, the rules below are applied to the absolute value of
$value
, and a minus sign is prepended to the result.
The value of $picture
consists of a primary format token,
optionally followed
by a format modifier. The primary format token is always present and
The primary format token is classified as one of the following:
A decimaldigitpattern made up of optionaldigitsigns, mandatorydigitsigns, and groupingseparatorsigns.
The optionaldigitsign is the character "#".
A mandatorydigitsign is a 000
, 001
, or
999
.
a groupingseparatorsign is a nonalphanumeric character, that
is a
If the primary format token contains at least one Unicode digit
then it is taken as a decimal digit pattern, and in this case it ^((\p{Nd}#[^\p{N}\p{L}])+?)$
. If it contains
a digit but does not match this pattern, a
If a semicolon is to be used as a grouping separator, then the primary format token as a whole must be followed by another semicolon, to ensure that the grouping separator is not mistaken as a separator between the primary format token and the format modifier.
There
The corresponding output format is a decimal number, using this digit family, with
at least as many digits as there are mandatorydigitsigns in the
format token. Thus, a format token 1
generates the sequence 0 1
2 ... 10 11 12 ...
, and a format token 01
(or equivalently,
00
or 99
) generates the sequence 00 01 02 ...
09 10 11 12 ... 99 100 101
. A format token of ١
(ArabicIndic digit one) generates the sequence ١
then ٢
then ٣
...
The groupingseparatorsigns are handled as follows. The position of
grouping separators within the format token, counting backwards from the last
digit, indicates the position of grouping separators to appear within the
formatted number, and the character used as the groupingseparatorsign
within the format token indicates the character to be used as the corresponding
grouping separator in the formatted number. If groupingseparatorsigns
appear at regular intervals within the format token, that is if the same grouping
separator appears at positions forming a sequence N, 2N,
3N, ... for some integer value N (including the case
where there is only one number in the list), then the sequence is extrapolated to
the left, so grouping separators will be used in the formatted number at every
multiple of N. For example, if the format token is 0'000
then the number one million will be formatted as 1'000'000
, while the
number fifteen will be formatted as 0'015
.
The only purpose of optionaldigitsigns is to mark the position of
groupingseparatorsigns. For example, if the format token is
#'##0
then the number one million will be formatted as
1'000'000
, while the number fifteen will be formatted as
15
. A grouping separator is included in the formatted number only
if there is a digit to its left, which will only be the case if either (a) the
number is large enough to require that digit, or (b) the number of
mandatorydigitsigns in the format token requires insignificant
leading zeros to be present.
Numbers will never be truncated. Given the decimaldigitpattern
01
, the number three hundred will be output as 300
,
despite the absence of any optionaldigitsign.
The format token A
, which generates the sequence A B C ... Z AA AB
AC...
.
The format token a
, which generates the sequence a b c ... z aa ab
ac...
.
The format token i
, which generates the sequence i ii iii iv v vi vii
viii ix x ...
.
The format token I
, which generates the sequence I II III IV V VI VII
VIII IX X ...
.
The format token w
, which generates numbers written as lowercase words, for
example in English, one two three four ...
The format token W
, which generates numbers written as uppercase words, for
example in English, ONE TWO THREE FOUR ...
The format token Ww
, which generates numbers written as titlecase words, for
example in English, One Two Three Four ...
Any other format token, which indicates a numbering sequence in which that token
represents the number 1 (one) (but see the note below).
It is 1
.
In some traditional numbering sequences additional signs are added to denote
that the letters should be interpreted as numbers; these are not included in
the format token. An example (see also the example below) is classical Greek
where a
For all format tokens other than the first kind above (one that consists of decimal
digits), there ①
(circled
digit one, ①) has a range of 1 to 20 imposed by the Unicode character repertoire. For
the numbering sequences described above any upper bound imposed by the implementation
1
.
The above expansions of numbering sequences for format tokens such as a
and
i
are indicative but not prescriptive. There are various conventions in
use for how alphabetic sequences continue when the alphabet is exhausted, and differing
conventions for how roman numerals are written (for example, IV
versus
IIII
as the representation of the number 4). Sometimes alphabetic
sequences are used that omit letters such as i
and o
. This
specification does not prescribe the detail of any sequence other than those sequences
consisting entirely of decimal digits.
Many numbering sequences are languagesensitive. This applies especially to the sequence
selected by the tokens w
, W
and Ww
. It also
applies to other sequences, for example different languages using the Cyrillic alphabet
use different sequences of characters, each starting with the letter #x410 (Cyrillic
capital letter A). In such cases, the $lang
argument specifies which
language's conventions are to be used. xml:lang
attribute (see
The set of languages
for which numbering is supported is $lang
argument is absent,
or is set to an empty sequence, or is invalid, or is not a language supported by the
implementation, then the number is formatted using
The format modifier ^([co]\(.+\))?[at]?$
.
either c
or o
, optionally followed by
a sequence of characters enclosed between parentheses, to indicate cardinal or
ordinal numbering respectively, the default being cardinal numbering
either a
or t
, to indicate alphabetic
or traditional numbering respectively, the default being
If the o
modifier is present, this indicates a request to output ordinal
numbers rather than cardinal numbers. For example, in English, when used with the format
token 1
, this outputs the sequence 1st 2nd 3rd 4th ...
, and
when used with the format token w
outputs the sequence first second
third fourth ...
.
The string of characters between the parentheses, if present, is used to
select between other possible variations of cardinal or ordinal numbering sequences.
The interpretation of this string is
For example, in some languages, ordinal numbers vary depending on the grammatical context:
they may have different genders and may decline with the noun that they qualify.
In such cases the string appearing in parentheses after the letter o
may be
used to indicate the variation of the ordinal number required. The way in which the
variation is indicated will depend on the conventions of the language. For inflected
languages that vary the ending of the word, the o(e)
, o(er)
, o(es)
, o(en)
.
It is
The specification "1o(º)"
with $lang
equal to
it
, if supported, should produce the sequence:
The specification "Wwo"
with $lang
equal to
it
, if supported, should produce the sequence:
The a
or t
modifiera
and i
. In some languages, the first member of
each sequence is the same, and so the format token alone would be ambiguous. a
or t
modifier,
the default is
A
Note the careful distinction between conditions that are errors and conditions where fallback occurs. The principle is that an error in the syntax of the format picture will be reported by all processors, while a construct that is recognized by some implementations but not others will never result in an error, but will instead cause a fallback representation of the integer to be used.
The expression formatinteger(123, '0000')
returns "0123"
.
formatinteger(123, 'w')
might return "one hundred and
twentythree"
The expression formatinteger(21, '1;o', 'en')
returns "21st"
.
formatinteger(14, 'Ww;o(e)', 'de')
might return
"Vierzehnte"
The expression formatinteger(7, 'a')
returns "g"
.
The expression formatinteger(57, 'I')
returns "LVII"
.
The expression formatinteger(1234, '#;##0;')
returns "1;234"
.
This section defines a function for formatting decimal and floating point numbers.
Function  Meaning 

fn:formatnumber  Returns a string containing a number formatted according to a given picture string, taking account of decimal formats specified in the static context. 
This function can be used to format any numeric quantity, including an integer. For integers, however,
the fn:formatinteger
function offers additional possibilities. Note also that the picture
strings used by the two functions are not 100% compatible, though they share some options in common.
Decimal formats are defined in the static context, and the way they are defined is therefore outside the scope of this specification. XSLT and XQuery both provide custom syntax for creating a decimal format.
The static context provides a set of decimal formats. One of the decimal formats is unnamed, the others (if any)
are identified by a QName. There is always an unnamed decimal format available, but its contents are
Each decimal format provides a set of named variables, described in the following table:
Name  Type  Usage (nonnormative) 

decimalseparatorsign  A single  Defines the character used to represent the decimal point (typically ".") both in the picture string and in the formatted number 
groupingseparatorsign  A single  Defines the character used to separate groups of digits (typically ",") both in the picture string and in the formatted number 
infinity  A  Defines the string used to represent the value positive or negative infinity in the formatted number (typically "Infinity") 
minussign  A single  Defines the character used as a minus sign in the formatted number if there is no subpicture for formatting negative numbers (typically "", x2D) 
NaN  A  Defines the string used to represent the value NaN in the formatted number 
percentsign  A single  Defines the character used as a percent sign (typically "%") both in the picture string and in the formatted number 
permillesign  A single  Defines the character used as a permille sign (typically "‰", x2030) both in the picture string and in the formatted number 
mandatorydigitsign  A single  Defines the character (typically "0") used in the picture string to represent a mandatory digit, and in the formatted number to represent the digit zero; by implication, this also defines the characters used to represent the digits one to nine. 
optionaldigitsign  A single  Defines the character used in the picture string to represent an optional digit (typically "#") 
patternseparatorsign  A single  Defines the character used in the picture string to separate the positive and negative subpictures (typically ";") 
It is a constraint that,
for any named or unnamed decimal format, the variables
representing characters used in a
Returns a string containing a number formatted according to a given picture string, taking account of decimal formats specified in the static context.
The twoargument form of this function is
The threeargument form of this function is
The effect of the twoargument form of the function is equivalent to calling the threeargument form with an empty sequence as the value of the third argument.
The function formats $value
as a string using the $picture
argument and the decimalformat named by the
$decimalformatname
argument, or the default decimalformat, if there
is no $decimalformatname
argument. The syntax of the picture string is
described in
The $value
argument may be of any numeric data type
(xs:double
, xs:float
, xs:decimal
, or their
subtypes including xs:integer
). Note that if an xs:decimal
is
supplied, it is not automatically promoted to an xs:double
, as such
promotion can involve a loss of precision.
If the supplied value of the $value
argument is an empty sequence, the
function behaves as if the supplied value were the xs:double
value
NaN
.
The value of $decimalformatname
,
EQName
as defined in the XPath 3.0 grammar, that is one of the following
A lexical QName, which is expanded using the
A URIQualifiedName
using the syntax Q{uri}local
,
where the URI can be zerolength to indicate a name in no namespace.
The decimal format that is used is the decimal format
in the static context whose name matches $decimalformatname
if supplied,
or the default decimal format in the static context otherwise.
The evaluation of the
The analysis phase takes as its inputs the
The result of the function is the formatted string representation of the supplied number.
A $decimalformatname
argument is
URIQualifiedName
Numbers will always be formatted with the most significant digit on the left.
The following examples assume a default decimal format in which the chosen digits are the ASCII digits 09, the decimal separator is ".", the grouping separator is ",", the minussign is "", and the percentsign is "%".
The expression formatnumber(12345.6, '#,###.00')
returns "12,345.00"
.
The expression formatnumber(12345678.9, '9,999.99')
returns "12,345,678.90"
.
The expression formatnumber(123.9, '9999')
returns "0124"
.
The expression formatnumber(0.14, '01%')
returns "14%"
.
The expression formatnumber(6, '000')
returns "006"
.
The following example assumes the existence of a decimal format named 'ch' in which the grouping
separator is ʹ
and the decimal separator is ·
:
The expression formatnumber(1234.5678, '#ʹ##0·00', 'ch')
returns "1ʹ234·57"
.
This differs from the formatnumber
function previously defined in XSLT 2.0 in that
any digit can be used in the picture string to represent a mandatory digit: for example the picture
strings '000', '001', and '999' are equivalent. This is to align formatnumber
(which previously used '000') with formatdateTime
(which used '001').
The integer part of the subpicture is defined as the part that appears to the left of the decimalseparatorsign if there is one, or the entire subpicture otherwise. The fractional part of the subpicture is defined as the part that appears to the right of the decimalseparatorsign if there is one; it is a zerolength string otherwise.
A
A picturestring consists either of a subpicture, or of
two subpictures separated by a patternseparatorsign. A picturestring
A subpicture
A subpicture
A subpicture
A subpicture
A subpicture
The integer part of a subpicture
This phase of the algorithm analyses
the
Several variables are associated with each subpicture. If there are two subpictures, then these rules are applied to one subpicture to obtain the values that apply to positive numbers, and to the other to obtain the values that apply to negative numbers. If there is only one subpicture, then the values for both cases are derived from this subpicture.
The variables are as follows:
The integerpartgroupingpositions is a sequence of integers representing the positions of grouping separators within the integer part of the subpicture. For each groupingseparatorsign that appears within the integer part of the subpicture, this sequence contains an integer that is equal to the total number of optionaldigitsign and decimaldigitfamily characters that appear within the integer part of the subpicture and to the right of the groupingseparatorsign. In addition, if these integerpartgroupingpositions are at regular intervals (that is, if they form a sequence N, 2N, 3N, ... for some integer value N, including the case where there is only one number in the list), then the sequence contains all integer multiples of N as far as necessary to accommodate the largest possible number.
The minimumintegerpartsize is an integer indicating the minimum number of digits that will appear to the left of the decimalseparatorsign. It is normally set to the number of decimaldigitfamily characters found in the integer part of the subpicture. But if the subpicture contains no decimaldigitfamily character and no decimalseparatorsign, it is set to one.
There is no maximum integer part size. All significant digits in the integer part of the number will be displayed, even if this exceeds the number of optionaldigitsign and decimaldigitfamily characters in the subpicture.
The prefix is set to contain all passive characters in the subpicture to the left of the leftmost active character. If the picture string contains only one subpicture, the prefix for the negative subpicture is set by concatenating the minussign character and the prefix for the positive subpicture (if any), in that order.
The fractionalpartgroupingpositions is a sequence of integers representing the positions of grouping separators within the fractional part of the subpicture. For each groupingseparatorsign that appears within the fractional part of the subpicture, this sequence contains an integer that is equal to the total number of optionaldigitsign and decimaldigitfamily characters that appear within the fractional part of the subpicture and to the left of the groupingseparatorsign.
The minimumfractionalpartsize is set to the number of decimaldigitfamily characters found in the fractional part of the subpicture.
The maximumfractionalpartsize is set to the total number of optionaldigitsign and decimaldigitfamily characters found in the fractional part of the subpicture.
The suffix is set to contain all passive characters to the right of the rightmost active character in the fractional part of the subpicture.
If there is only one subpicture, then all variables for positive numbers and negative numbers will be the same, except for prefix: the prefix for negative numbers will be preceded by the minussign character.
This section describes the second phase of processing of the
fn:formatnumber
function. This phase takes as input a number to be formatted
(referred to as the fn:formatnumber
function.
The algorithm for this second stage of processing is as follows:
If the input number is NaN (not a number), the result is the specified NaNsymbol (with no prefix or suffix).
In the rules below, the positive subpicture and its associated variables are used if the input number is positive, and the negative subpicture and its associated variables are used otherwise. Negative zero is taken as negative, positive zero as positive.
If the input number is positive or negative infinity, the result is the concatenation of the appropriate prefix, the infinitysymbol, and the appropriate suffix.
If the subpicture contains a percentsign, the number is multiplied by 100. If the subpicture contains a permillesign, the number is multiplied by 1000. The resulting number is referred to below as the adjusted number.
The adjusted number is converted (if necessary) to
an xs:decimal
value,
using an implementation of xs:decimal
that imposes no limits on the
totalDigits
or fractionDigits
facets. If there are several
such values that
are numerically equal to the adjusted number (bearing in mind that if the
adjusted number is an xs:double
or xs:float
, the comparison will be done by
converting the decimal value back to an xs:double
or xs:float
), the one that
is chosen maximumfractionalpartsize
digits in
its fractional part. The rounded number is defined to be the result of
converting the adjusted number to an xs:decimal
value, as described above,
and then calling the function fn:roundhalftoeven
with this converted number
as the first argument and the maximumfractionalpartsize
as the second
argument, again with no limits on the totalDigits
or fractionDigits
in the
result.
The absolute value of the rounded number is converted to a string in decimal notation, with no insignificant leading or trailing zeroes, using the digits in the decimaldigitfamily to represent the ten decimal digits, and the decimalseparatorsign to separate the integer part and the fractional part. (The value zero will at this stage be represented by a decimalseparatorsign on its own.)
If the number of digits to the left of the decimalseparatorsign is less than minimumintegerpartsize, leading zerodigitsign characters are added to pad out to that size.
If the number of digits to the right of the decimalseparatorsign is less than minimumfractionalpartsize, trailing zerodigitsign characters are added to pad out to that size.
For each integer N in the integerpartgroupingpositions list, a groupingseparatorsign character is inserted into the string immediately after that digit that appears in the integer part of the number and has N digits between it and the decimalseparatorsign, if there is such a digit.
For each integer N in the fractionalpartgroupingpositions list, a groupingseparatorsign character is inserted into the string immediately before that digit that appears in the fractional part of the number and has N digits between it and the decimalseparatorsign, if there is such a digit.
If there is no decimalseparatorsign in the subpicture, or if there are no digits to the right of the decimalseparatorsign character in the string, then the decimalseparatorsign character is removed from the string (it will be the rightmost character in the string).
The result of the function is the concatenation of the appropriate prefix, the string conversion of the number as obtained above, and the appropriate suffix.
The functions in this section perform trigonometric and other mathematical calculations on xs:double
values. They
are provided primarily for use in applications performing geometrical computation, for example when generating
SVG graphics.
Functions are provided to support the six most commonly used trigonometric calculations: sine, cosine and tangent, and their inverses arc sine, arc cosine, and arc tangent. Other functions such as secant, cosecant, and cotangent are not provided because they are easily computed in terms of these six.
The functions in this section (with the exception of math:pi
)
are specified by reference to xs:double
values. The IEEE specification
applies with the following caveats:
IEEE states that the preferred quantum is languagedefined. In this
specification, it is
IEEE states that certain functions should raise the inexact exception if the result is inexact. In this specification, this exception if it occurs does not result in an error. Any diagnostic information is outside the scope of this specification.
IEEE defines various rounding algorithms for inexact results, and states
that the choice of rounding direction, and the mechanisms for influencing this choice,
are languagedefined. In this specification, the rounding direction and any mechanisms for
influencing it are
Certain operations (such as taking the square root of a negative number)
are defined in IEEE to signal the invalid operation exception and return a
quiet NaN. In this specification, such operations return NaN
and do not raise an error. The same policy applies to operations (such as taking
the logarithm of zero) that raise a dividebyzero exception. Any diagnostic
information is outside the scope of this specification.
Operations whose mathematical result is greater than the largest finite xs:double
value are defined in IEEE to signal the overflow exception; operations whose mathematical
result is closer to zero than the smallest nonzero xs:double
value are similarly
defined in IEEE to signal the underflow exception. The treatment of these exceptions in
this specification is defined in
Function  Meaning 

math:pi  Returns an approximation to the mathematical constant π. 
math:exp  Returns the value of e^{x}. 
math:exp10  Returns the value of 10 ^{x}. 
math:log  Returns the natural logarithm of the argument. 
math:log10  Returns the baseten logarithm of the argument. 
math:pow  Returns the result of raising the first argument to the power of the second. 
math:sqrt  Returns the nonnegative square root of the argument. 
math:sin  Returns the sine of the argument, expressed in radians. 
math:cos  Returns the cosine of the argument, expressed in radians. 
math:tan  Returns the tangent of the argument, expressed in radians. 
math:asin  Returns the arc sine of the argument, the result being in the range π/2 to +π/2 radians. 
math:acos  Returns the arc cosine of the argument, the result being in the range zero to +π radians. 
math:atan  Returns the arc tangent of the argument, the result being in the range π/2 to +π/2 radians. 
math:atan2  Returns the angle in radians subtended at the origin by the point on a plane with coordinates (x, y) and the positive xaxis, the result being in the range π to +π. 
Returns an approximation to the mathematical constant π.
This function is
This function returns the xs:double
value whose lexical representation is
3.141592653589793e0
The expression 2*math:pi()
returns 6.283185307179586e0
.
The expression 60 * (math:pi() div 180)
converts an angle of 60 degrees
to radians.
Returns the value of e^{x}.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise the result is the mathematical constant e
raised to the power of $arg
, as defined in the exp
function applied to 64bit binary floating point
values.
The treatment of overflow and underflow is defined in
The expression math:exp(())
returns ()
.
The expression math:exp(0)
returns 1.0e0
.
The expression math:exp(1)
returns 2.7182818284590455e0
.
The expression math:exp(2)
returns 7.38905609893065e0
.
The expression math:exp(1)
returns 0.36787944117144233e0
.
The expression math:exp(math:pi())
returns 23.140692632779267e0
.
The expression math:exp(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:exp(xs:double('INF'))
returns xs:double('INF')
.
The expression math:exp(xs:double('INF'))
returns 0.0e0
.
Returns the value of 10
^{x}.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise the result is ten raised to the power of $arg
,
as defined in the exp10
function applied to 64bit binary floating point values.
The treatment of overflow and underflow is defined in
The expression math:exp10(())
returns ()
.
The expression math:exp10(0)
returns 1.0e0
.
The expression math:exp10(1)
returns 1.0e1
.
The expression math:exp10(0.5)
returns 3.1622776601683795e0
.
The expression math:exp10(1)
returns 1.0e1
.
The expression math:exp10(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:exp10(xs:double('INF'))
returns xs:double('INF')
.
The expression math:exp10(xs:double('INF'))
returns 0.0e0
.
Returns the natural logarithm of the argument.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise the result is the natural logarithm of $arg
, as
defined in the log
function applied to 64bit binary floating point values.
The treatment of divideByZero
and invalidOperation
exceptions
is defined in NaN
.
The expression math:log(())
returns ()
.
The expression math:log(0)
returns xs:double('INF')
.
The expression math:log(math:exp(1))
returns 1.0e0
.
The expression math:log(1.0e3)
returns 6.907755278982137e0
.
The expression math:log(2)
returns 0.6931471805599453e0
.
The expression math:log(1)
returns xs:double('NaN')
.
The expression math:log(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:log(xs:double('INF'))
returns xs:double('INF')
.
The expression math:log(xs:double('INF'))
returns xs:double('NaN')
.
Returns the baseten logarithm of the argument.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise the result is the base10 logarithm of $arg
, as
defined in the log10
function applied to 64bit binary floating point values.
The treatment of divideByZero
and invalidOperation
exceptions
is defined in NaN
.
The expression math:log10(())
returns ()
.
The expression math:log10(0)
returns xs:double('INF')
.
The expression math:log10(1.0e3)
returns 3.0e0
.
The expression math:log10(1.0e3)
returns 3.0e0
.
The expression math:log10(2)
returns 0.3010299956639812e0
.
The expression math:log10(1)
returns xs:double('NaN')
.
The expression math:log10(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:log10(xs:double('INF'))
returns xs:double('INF')
.
The expression math:log10(xs:double('INF'))
returns xs:double('NaN')
.
Returns the result of raising the first argument to the power of the second.
This function is
If $x
is the empty sequence, the function returns the empty sequence.
If $y
is an instance of xs:integer
, the result is
$x
raised to the power of $y
as defined in the pown
function applied to a
64bit binary floating point value and an integer.
Otherwise $y
is converted to an xs:double
by numeric
promotion, and the result is the value of $x
raised to the power of
$y
as defined in the pow
function applied to two 64bit binary floating point values.
The treatment of the divideByZero
and invalidOperation
exceptions is defined in
The expression math:pow((), 93.7)
returns ()
.
The expression math:pow(2, 3)
returns 8.0e0
.
The expression math:pow(2, 3)
returns 8.0e0
.
The expression math:pow(2, 3)
returns 0.125e0
.
The expression math:pow(2, 3)
returns 0.125e0
.
The expression math:pow(2, 0)
returns 1.0e0
.
The expression math:pow(0, 0)
returns 1.0e0
.
The expression math:pow(xs:double('INF'), 0)
returns 1.0e0
.
The expression math:pow(xs:double('NaN'), 0)
returns 1.0e0
.
The expression math:pow(math:pi(), 0)
returns 1.0e0
.
The expression math:pow(0e0, 3)
returns 0.0e0
.
The expression math:pow(0e0, 4)
returns 0.0e0
.
The expression math:pow(0e0, 3)
returns 0.0e0
.
The expression math:pow(0, 4)
returns 0.0e0
.
The expression math:pow(0e0, 3)
returns xs:double('INF')
.
The expression math:pow(0e0, 4)
returns xs:double('INF')
.
The expression math:pow(0e0, 3)
returns xs:double('INF')
.
The expression math:pow(0, 4)
returns xs:double('INF')
.
The expression math:pow(16, 0.5e0)
returns 4.0e0
.
The expression math:pow(16, 0.25e0)
returns 2.0e0
.
The expression math:pow(0e0, 3.0e0)
returns xs:double('INF')
.
The expression math:pow(0e0, 3.0e0)
returns xs:double('INF')
.
The expression math:pow(0e0, 3.1e0)
returns xs:double('INF')
.
The expression math:pow(0e0, 3.1e0)
returns xs:double('INF')
.
The expression math:pow(0e0, 3.0e0)
returns 0.0e0
.
The expression math:pow(0e0, 3.0e0)
returns 0.0e0
.
The expression math:pow(0e0, 3.1e0)
returns 0.0e0
.
The expression math:pow(0e0, 3.1e0)
returns 0.0e0
.
The expression math:pow(1, xs:double('INF'))
returns 1.0e0
.
The expression math:pow(1, xs:double('INF'))
returns 1.0e0
.
The expression math:pow(1, xs:double('INF'))
returns 1.0e0
.
The expression math:pow(1, xs:double('INF'))
returns 1.0e0
.
The expression math:pow(1, xs:double('NaN'))
returns 1.0e0
.
The expression math:pow(2.5e0, 2.0e0)
returns 6.25e0
.
The expression math:pow(2.5e0, 2.00000001e0)
returns xs:double('NaN')
.
Returns the nonnegative square root of the argument.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise the result is the mathematical nonnegative square root of
$arg
as defined in the squareRoot
function applied to 64bit binary floating point values.
The treatment of the invalidOperation
exception is defined in NaN
.
If $arg
is positive or negative zero, positive infinity, or
NaN
, then the result is $arg
. (Negative zero is the only
case where the result can have negative sign)
The expression math:sqrt(())
returns ()
.
The expression math:sqrt(0.0e0)
returns 0.0e0
.
The expression math:sqrt(0.0e0)
returns 0.0e0
.
The expression math:sqrt(1.0e6)
returns 1.0e3
.
The expression math:sqrt(2.0e0)
returns 1.4142135623730951e0
.
The expression math:sqrt(2.0e0)
returns xs:double('NaN')
.
The expression math:sqrt(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:sqrt(xs:double('INF'))
returns xs:double('INF')
.
The expression math:sqrt(xs:double('INF'))
returns xs:double('NaN')
.
Returns the sine of the argument, expressed in radians.
This function is
If $
θ is the empty sequence, the function returns the empty
sequence.
Otherwise the result is the sine of $
θ,
treated as an angle in radians, as defined in the sin
function applied to 64bit binary floating point
values.
The treatment of the invalidOperation
and underflow
exceptions
is defined in
If $
θ is positive or negative zero, the result is
$
θ.
If $
θ is positive or negative infinity, or NaN
,
then the result is NaN
.
Otherwise the result is always in the range 1.0e0 to +1.0e0
The expression math:sin(())
returns ()
.
The expression math:sin(0)
returns 0.0e0
.
The expression math:sin(0.0e0)
returns 0.0e0
.
The expression math:sin(math:pi() div 2)
returns 1.0e0
.
The expression math:sin(math:pi() div 2)
returns 1.0e0
.
The expression math:sin(math:pi())
returns 0.0e0
(approximately).
The expression math:sin(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:sin(xs:double('INF'))
returns xs:double('NaN')
.
The expression math:sin(xs:double('INF'))
returns xs:double('NaN')
.
Returns the cosine of the argument, expressed in radians.
This function is
If $
θ is the empty sequence, the function returns the empty
sequence.
If $
θ is positive or negative infinity, or NaN
,
then the result is NaN
.
Otherwise the result is the cosine of $
θ,
treated as an angle in radians, as defined in the cos
function applied to 64bit binary floating point
values.
The treatment of the invalidOperation
exception is defined in
If $
θ is positive or negative zero, the result is
$
θ.
If $
θ is positive or negative infinity, or NaN
,
then the result is NaN
.
Otherwise the result is always in the range 1.0e0 to +1.0e0
The expression math:cos(())
returns ()
.
The expression math:cos(0)
returns 1.0e0
.
The expression math:cos(0.0e0)
returns 1.0e0
.
The expression math:cos(math:pi() div 2)
returns 0.0e0
(approximately).
The expression math:cos(math:pi() div 2)
returns 0.0e0
(approximately).
The expression math:cos(math:pi())
returns 1.0e0
.
The expression math:cos(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:cos(xs:double('INF'))
returns xs:double('NaN')
.
The expression math:cos(xs:double('INF'))
returns xs:double('NaN')
.
Returns the tangent of the argument, expressed in radians.
This function is
If $
θ is the empty sequence, the function returns the empty
sequence.
Otherwise the result is the tangent of $
θ,
treated as an angle in radians, as defined in the tan
function applied to 64bit binary floating point
values.
The treatment of the invalidOperation
and underflow
exceptions
is defined in
If $
θ is positive or negative infinity, or NaN
,
then the result is NaN
.
The expression math:tan(())
returns ()
.
The expression math:tan(0)
returns 0.0e0
.
The expression math:tan(0.0e0)
returns 0.0e0
.
The expression math:tan(math:pi() div 4)
returns 1.0e0
(approximately).
The expression math:tan(math:pi() div 4)
returns 1.0e0
(approximately).
The expression math:tan(math:pi() div 2)
returns 1.633123935319537E16
(approximately).
The expression math:tan(math:pi() div 2)
returns 1.633123935319537E16
(approximately).
The expression math:tan(math:pi())
returns 0.0e0
(approximately).
The expression math:tan(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:tan(xs:double('INF'))
returns xs:double('NaN')
.
The expression math:tan(xs:double('INF'))
returns xs:double('NaN')
.
Returns the arc sine of the argument, the result being in the range π/2 to +π/2 radians.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise the result is the arc sine of $
θ,
treated as an angle in radians, as defined in the asin
function applied to 64bit binary floating point
values.
The treatment of the invalidOperation
and underflow
exceptions
is defined in
If $arg
is positive or negative zero, the result is $arg
.
If $arg
is NaN
, or if its absolute value is greater than one,
then the result is NaN
.
In other cases the result is an xs:double
value representing an angle
θ in radians in the range π/2 <=
$
θ <= +
π/2
.
The expression math:asin(())
returns ()
.
The expression math:asin(0)
returns 0.0e0
.
The expression math:asin(0.0e0)
returns 0.0e0
.
The expression math:asin(1.0e0)
returns 1.5707963267948966e0
(approximately).
The expression math:asin(1.0e0)
returns 1.5707963267948966e0
(approximately).
The expression math:asin(2.0e0)
returns xs:double('NaN')
.
The expression math:asin(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:asin(xs:double('INF'))
returns xs:double('NaN')
.
The expression math:asin(xs:double('INF'))
returns xs:double('NaN')
.
Returns the arc cosine of the argument, the result being in the range zero to +π radians.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise the result is the arc cosine of $
θ,
treated as an angle in radians, as defined in the acos
function applied to 64bit binary floating point
values.
The treatment of the invalidOperation
exception is defined in
If $arg
is NaN
, or if its absolute value is greater than one,
then the result is NaN
.
In other cases the result is an xs:double
value representing an angle
θ in radians in the range 0 <= $
θ <=
+
π.
The expression math:acos(())
returns ()
.
The expression math:acos(0)
returns 1.5707963267948966e0
(approximately).
The expression math:acos(0.0e0)
returns 1.5707963267948966e0
(approximately).
The expression math:acos(1.0e0)
returns 0.0e0
.
The expression math:acos(1.0e0)
returns 3.141592653589793e0
(approximately).
The expression math:acos(2.0e0)
returns xs:double('NaN')
.
The expression math:acos(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:acos(xs:double('INF'))
returns xs:double('NaN')
.
The expression math:acos(xs:double('INF'))
returns xs:double('NaN')
.
Returns the arc tangent of the argument, the result being in the range π/2 to +π/2 radians.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise the result is the arc tangent of $
θ,
treated as an angle in radians, as defined in the atan
function applied to 64bit binary floating point
values.
The treatment of the underflow
exception is defined in
If $arg
is positive or negative zero, the result is $arg
.
If $arg
is NaN
then the result is NaN
.
In other cases the result is an xs:double
value representing an angle
θ in radians in the range π/2 <=
$
θ <= +
π/2
.
The expression math:atan(())
returns ()
.
The expression math:atan(0)
returns 0.0e0
.
The expression math:atan(0.0e0)
returns 0.0e0
.
The expression math:atan(1.0e0)
returns 0.7853981633974483e0
(approximately).
The expression math:atan(1.0e0)
returns 0.7853981633974483e0
(approximately).
The expression math:atan(xs:double('NaN'))
returns xs:double('NaN')
.
The expression math:atan(xs:double('INF'))
returns 1.5707963267948966e0
(approximately).
The expression math:atan(xs:double('INF'))
returns 1.5707963267948966e0
(approximately).
Returns the angle in radians subtended at the origin by the point on a plane with coordinates (x, y) and the positive xaxis, the result being in the range π to +π.
This function is
The result is the value of atan2(y, x)
as defined in the
atan2
function applied
to 64bit binary floating point values.
The treatment of the underflow
exception is defined in
If NaN
then the result is NaN
.
If $y
is positive and $x
is positive and finite, then
(subject to rules for overflow, underflow and approximation)
the value of atan2($y, $x)
is atan($y div $x)
.
If $y
is positive and $x
is negative and finite, then
(subject to the same caveats)
the value of atan2($y, $x)
is π  atan($y div $x)
.
Some results for special values of the arguments are shown in the examples below.
The expression math:atan2(+0.0e0, 0.0e0)
returns 0.0e0
.
The expression math:atan2(0.0e0, 0.0e0)
returns 0.0e0
.
The expression math:atan2(+0.0e0, 0.0e0)
returns math:pi()
.
The expression math:atan2(0.0e0, 0.0e0)
returns math:pi()
.
The expression math:atan2(1, 0.0e0)
returns math:pi() div 2
.
The expression math:atan2(+1, 0.0e0)
returns +math:pi() div 2
.
The expression math:atan2(0.0e0, 1)
returns math:pi()
.
The expression math:atan2(+0.0e0, 1)
returns +math:pi()
.
The expression math:atan2(0.0e0, +1)
returns 0.0e0
.
The expression math:atan2(+0.0e0, +1)
returns +0.0e0
.
This section specifies functions and operators on the xs:string
datatype and the datatypes derived from it.
The operators described in this section are defined on the following types. Each type whose name is indented is derived from the type whose name appears nearest above with one less level of indentation.
xs:string  
xs:normalizedString  
xs:token  
xs:language  
xs:NMTOKEN  
xs:Name  
xs:NCName  
xs:ID  
xs:IDREF  
xs:ENTITY 
They also apply to userdefined types derived by restriction from the above types.
Function  Meaning 

fn:codepointstostring  Creates an xs:string from a sequence of 
fn:stringtocodepoints  Returns the sequence of xs:string value. 
Creates an xs:string
from a sequence of
This function is
The function returns the string made up from the $arg
. This will be the zerolength string if $arg
is the empty sequence.
An error is raised $arg
is not a permitted XML character.
The expression fn:codepointstostring((66, 65, 67, 72))
returns "BACH"
.
The expression fn:codepointstostring((2309, 2358, 2378, 2325))
returns "अशॊक"
.
The expression fn:codepointstostring(())
returns ""
.
The expression fn:codepointstostring(0)
raises error FOCH0001
.
Returns the sequence of xs:string
value.
This function is
The function returns a sequence of integers, each integer being the Unicode $arg
.
If $arg
is a zerolength string or the empty sequence, the function returns
the empty sequence.
The expression fn:stringtocodepoints("Thérèse")
returns (84, 104, 233, 114, 232, 115, 101)
.
Function  Meaning 

fn:compare  Returns 1, 0, or 1, depending on whether $comparand1 collates
before, equal to, or after $comparand2 according to the rules of a selected
collation. 
fn:codepointequal  Returns true if two strings are equal, considered codepointbycodepoint. 
A collation is a specification of the manner in which xs:string
or a type derived from xs:string
are
compared (or, equivalently, sorted), the comparisons are inherently
performed according to some collation (even if that collation is defined
entirely on codepoint values). The
Collations can indicate that two different codepoints are, in fact, equal for comparison purposes (e.g., "v" and "w" are considered equivalent in some Swedish collations). Strings can be compared codepointbycodepoint or in a linguistically appropriate manner, as defined by the collation.
Some collations, especially those based on the
The
In the ideal case, a collation should treat two strings as equal if the two strings are identical after Unicode normalization. Thus, the
This specification assumes that collations are named and that the collation
name may be provided as an argument to string functions. Functions that
allow specification of a collation do so with an argument whose type is
xs:string
but whose lexical form must conform to an
xs:anyURI
. If the collation is specified using a relative URI reference,
This specification does not define whether or not the collation URI is
dereferenced. The collation URI may be an abstract identifier, or it may
refer to an actual resource describing the collation. If it refers to a
resource, this specification does not define the nature of that resource.
One possible candidate is that the resource is a locale description
expressed using the Locale Data Markup Language: see
Functions such as fn:compare
and fn:max
that
compare xs:string
values use a single collation URI to identify
all aspects of the collation rules. This means that any parameters such as
the strength of the collation must be specified as part of the collation
URI. For example, suppose there is a collation
that refers to a French collation that compares on the basis of
base characters. Collations that use the same basic rules, but with higher
strengths, for example, base characters and accents, or base characters,
accents and case, would need to be given different names, say http://www.example.com/collations/French
and http://www.example.com/collations/French1
. Note that some specifications use the term collation to refer to
an algorithm that can be parameterized, but in this specification, each
possible parameterization is considered to be a distinct collation.http://www.example.com/collations/French2
The XQuery/XPath static context includes a provision for a default collation
that can be used for string comparisons and ordering operations. See the
description of the static context in
XML allows elements to specify the xml:lang
attribute to
indicate the language associated with the content of such an element.
This specification does not use xml:lang
to identify the
default collation because using
xml:lang
does not produce desired effects when the two
strings to be compared have different xml:lang
values or
when a string is multilingual.
http://www.w3.org/2005/xpathfunctions/collation/codepoint
identifies
a collation which must be recognized by every implementation: it is referred to as
the
The Unicode codepoint collation does not perform any normalization on the supplied strings.
The collation is defined as follows. Each of the two strings is
converted to a sequence of integers using the fn:stringtocodepoints
function. These two sequences $A
and $B
are then compared as follows:
If both sequences are empty, the strings are equal
If one sequence is empty and the other is not, then the string corresponding to the empty sequence is less than the other string.
If the first integer in $A
is less than the first integer in $B
, then
the string corresponding to $A
is less than the string corresponding to
$B
.
If the first integer in $A
is greater than the first integer in $B
, then
the string corresponding to $A
is greater than the string corresponding to
$B
.
Otherwise (the first pair of integers are equal), the result is obtained
by applying the same rules recursively to fn:subsequence($A, 2)
and
fn:subsequence($B, 2)
While the Unicode codepoint collation does not produce results suitable for quality publishing of printed indexes or directories, it is adequate for many purposes where a restricted alphabet is used, such as sorting of vehicle registrations.
Many functions have two signatures, where one signature includes a $collation
argument and the other omits this argument.
The collation to use for these functions is determined by the following rules:
If the function specifies an explicit collation, CollationA (e.g., if
the optional collation argument is specified in a call of the
fn:compare
function), then:
If CollationA is supported by the implementation, then CollationA is used.
Otherwise, a
If no collation is explicitly specified for the function and the default collation in the XQuery/XPath static context is CollationB, then:
If CollationB is supported by the implementation, then CollationB is used.
Otherwise, a
Because the set of collations that are supported is
Returns 1, 0, or 1, depending on whether $comparand1
collates
before, equal to, or after $comparand2
according to the rules of a selected
collation.
The twoargument form of this function is
The threeargument form of this function is
Returns 1, 0, or 1, depending on whether the value of the $comparand1
is
respectively less than, equal to, or greater than the value of $comparand2
,
according to the rules of the collation that is used.
The collation used by this function is determined according to the rules in
If either $comparand1
or $comparand2
is the empty sequence,
the function returns the empty sequence.
This function, called with the first signature, defines the semantics of the "eq", "ne",
"gt", "lt", "le" and "ge" operators on xs:string
values.
The expression fn:compare('abc', 'abc')
returns 0
.
The expression fn:compare('Strasse', 'Straße')
returns 0
. ss
and the (German) character ß
(sharps
). Otherwise, the returned value depends on the
semantics of the default collation.).
The expression fn:compare('Strasse', 'Straße',
'http://example.com/deutsch')
returns 0
. http://example.com/deutsch
includes provisions that equate
ss
and the (German) character ß
(sharps
). Otherwise, the returned value depends on the
semantics of that collation.).
The expression fn:compare('Strassen', 'Straße')
returns 1
. ss
and the (German) character ß
(sharps
) with less strength than the differences between the
base characters, such as the final n
. ).
Returns true if two strings are equal, considered codepointbycodepoint.
This function is
If either argument is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns true
or false
depending on
whether the value of $comparand1
is equal to the value of
$comparand2
, according to the Unicode codepoint collation
(http://www.w3.org/2005/xpathfunctions/collation/codepoint
).
This function allows xs:anyURI
values to be compared without having to
specify the Unicode codepoint collation.
The expression fn:codepointequal("abcd", "abcd")
returns true()
.
The expression fn:codepointequal("abcd", "abcd ")
returns false()
.
The expression fn:codepointequal("", "")
returns true()
.
The expression fn:codepointequal("", ())
returns ()
.
The expression fn:codepointequal((), ())
returns ()
.
The following functions are defined on values of type xs:string
and
types derived from it.
Function  Meaning 

fn:concat  Returns the concatenation of the string values of the arguments. 
fn:stringjoin  Returns a string created by concatenating the items in a sequence, with a defined separator between adjacent items. 
fn:substring  Returns the portion of the value of $sourceString beginning at the
position indicated by the value of $start and continuing for the number of
$length . 
fn:stringlength  Returns the number of 
fn:normalizespace  Returns the value of $arg with leading and trailing whitespace
removed, and sequences of internal whitespace reduced to a single space character. 
fn:normalizeunicode  Returns the value of $arg after applying Unicode
normalization. 
fn:uppercase  Converts a string to upper case. 
fn:lowercase  Converts a string to lower case. 
fn:translate  Returns the value of $arg modified by replacing or removing
individual characters. 
When the above operators and functions are applied to datatypes derived from
xs:string
, they are guaranteed to return values that are instances of
xs:string
, but the value might or might not be an instance of the
particular subtype of xs:string
to which they were applied.
The strings returned by fn:concat
and fn:stringjoin
are not guaranteed to be normalized.
But see note in fn:concat
.
Returns the concatenation of the string values of the arguments.
The twoargument form of this function defines the semantics of the "" operator.
This function is
This function accepts two or more xs:anyAtomicType
arguments and casts each
one to xs:string
. The function returns the xs:string
that is
the concatenation of the values of its arguments after conversion. If any argument is
the empty sequence, that argument is treated as the zerolength string.
The fn:concat
function is specified to allow two or
more arguments, which are concatenated together. This is the only function specified in
this document that allows a variable number of arguments. This capability is retained
for compatibility with
As mentioned in fn:concat
. If a normalized result is required,
fn:normalizeunicode
can be applied to the xs:string
returned by fn:concat
. The following XQuery:
where the "?" represents either the actual Unicode character COMBINING DIARESIS (Unicode codepoint U+0308) or "̈", will return:
"I plan to go to Mu?nchen in September"
where the "?" represents either the actual Unicode character COMBINING DIARESIS (Unicode codepoint U+0308) or "̈". It is worth noting that the returned value is not normalized in NFC; however, it is normalized in NFD. .
However, the following XQuery:
where the "?" represents either the actual Unicode character COMBINING DIARESIS (Unicode codepoint U+0308) or "̈", will return:
"I plan to go to München in September"
This returned result is normalized in NFC.
The expression fn:concat('un', 'grateful')
returns "ungrateful"
.
The expression fn:concat('Thy ', (), 'old ', "groans", "", ' ring', ' yet', ' in', '
my', ' ancient',' ears.')
returns "Thy old groans ring yet in my ancient ears."
.
The expression fn:concat('Ciao!',())
returns "Ciao!"
.
The expression fn:concat('Ingratitude, ', 'thou ', 'marblehearted', ' fiend!')
returns "Ingratitude, thou marblehearted fiend!"
.
The expression fn:concat(01, 02, 03, 04, true())
returns "1234true"
.
The expression 10  '/'  6
returns "10/6"
.
Returns a string created by concatenating the items in a sequence, with a defined separator between adjacent items.
This function is
The effect of calling the singleargument version of this function is
the same as calling the twoargument version with $arg2
set to a
zerolength string.
The function returns an xs:string
created by concatenating the items in the
sequence $arg1
, in order, using the value of $arg2
as a
separator between adjacent items. If the value of $arg2
is the zerolength
string, then the members of $arg1
are concatenated without a separator.
If the value of $arg1
is the empty sequence, the function returns the
zerolength string.
The expression fn:stringjoin(('Now', 'is', 'the', 'time', '...'), ' ')
returns "Now is the time ..."
.
The expression fn:stringjoin(('Blow, ', 'blow, ', 'thou ', 'winter ', 'wind!'), '')
returns "Blow, blow, thou winter wind!"
.
The expression fn:stringjoin((), 'separator')
returns ""
.
Assume a document:
with the <section>
element as the context node, the
fn:stringjoin(ancestororself::*/name(), '/')
returns "doc/chap/section"
Returns the portion of the value of $sourceString
beginning at the
position indicated by the value of $start
and continuing for the number of
$length
.
This function is
If the value of $sourceString
is the empty sequence, the function returns
the zerolength string.
Otherwise, the function returns a string comprising those $sourceString
whose index position (counting
from one) is greater than or equal to the value of $start
(rounded to an
integer), and (if $length
is specified) less than the sum of
$start
and $length
(both rounded to integers).
The characters returned do not extend beyond $sourceString
. If
$start
is zero or negative, only those characters in positions greater
than zero are returned.
More specifically, the three argument version of the function returns the characters in
$sourceString
whose position $p
satisfies:
fn:round($start) <= $p < fn:round($start) + fn:round($length)
The two argument version of the function assumes that $length
is infinite
and thus returns the $sourceString
whose position $p
satisfies:
fn:round($start) <= $p
In the above computations, the rules for op:numericlessthan
and
op:numericgreaterthan
apply.
The first character of a string is located at position 1, not position 0.
The expression fn:substring("motor car", 6)
returns " car"
. $sourceString
are selected.).
The expression fn:substring("metadata", 4, 3)
returns "ada"
.
The expression fn:substring("12345", 1.5, 2.6)
returns "234"
.
The expression fn:substring("12345", 0, 3)
returns "12"
.
The expression fn:substring("12345", 5, 3)
returns ""
.
The expression fn:substring("12345", 3, 5)
returns "1"
.
The expression fn:substring("12345", 0 div 0E0, 3)
returns ""
. 0 div 0E0
returns NaN
, and
NaN
compared to any other number returns false
, no
characters are selected.).
The expression fn:substring("12345", 1, 0 div 0E0)
returns ""
.
The expression fn:substring((), 1, 3)
returns ""
.
The expression fn:substring("12345", 42, 1 div 0E0)
returns "12345"
. INF
are selected.).
The expression fn:substring("12345", 1 div 0E0, 1 div 0E0)
returns ""
. INF + INF
is NaN
, no
characters are selected.).
Returns the number of
The zeroargument form of this function is
The oneargument form of this function is
The function returns an xs:integer
equal to the length in $arg
.
Calling the zeroargument version of the function is equivalent to calling
fn:stringlength(fn:string(.))
.
If the value of $arg
is the empty sequence, the function returns the
xs:integer
value zero (0).
If $arg
is not specified and the context item is
Unlike some programming languages, a
The expression fn:stringlength("Harp not on that string, madam; that is past.")
returns 45
.
The expression fn:stringlength(())
returns 0
.
Returns the value of $arg
with leading and trailing whitespace
removed, and sequences of internal whitespace reduced to a single space character.
The zeroargument form of this function is
The oneargument form of this function is
If the value of $arg
is the empty sequence, the function returns the
zerolength string.
The function returns a string constructed by stripping leading and trailing whitespace
from the value of $arg
, and replacing sequences of one or more adjacent
whitespace characters with a single space, #x20
.
The whitespace characters are defined in the metasymbol S (Production 3) of
If no argument is supplied, then $arg
defaults to the
string value (calculated using fn:string
) of the context item
(.
).
If no argument is supplied and the context item is
The definition of whitespace is unchanged in
The expression fn:normalizespace(" The wealthy curled darlings
of our nation. ")
returns "The wealthy curled darlings of our nation."
.
The expression fn:normalizespace(())
returns ""
.
Returns the value of $arg
after applying Unicode
normalization.
This function is
If the value of $arg
is the empty sequence, the function returns the
zerolength string.
If the singleargument version of the function is used, the result is the same as
calling the twoargument version with $normalizationForm
set to the string
"NFC".
Otherwise, the function returns the value of $arg
normalized according to
the rules of the normalization form identified by the value of
$normalizationForm
.
The effective value of $normalizationForm
is the value of the expression
fn:uppercase(fn:normalizespace($normalizationForm))
.
See
If the effective value of $normalizationForm
is NFC
,
then the function returns the value of $arg
converted to Unicode
Normalization Form C (NFC).
If the effective value of $normalizationForm
is NFD
,
then the function returns the value of $arg
converted to Unicode
Normalization Form D (NFD).
If the effective value of $normalizationForm
is NFKC
,
then the function returns the value of $arg
in Unicode Normalization
Form KC (NFKC).
If the effective value of $normalizationForm
is NFKD
,
then the function returns the value of $arg
converted to Unicode
Normalization Form KD (NFKD).
If the effective value of $normalizationForm
is
FULLYNORMALIZED
, then the function returns the value of
$arg
converted to fully normalized form.
If the effective value of $normalizationForm
is the zerolength
string, no normalization is performed and $arg
is returned.
Normalization forms NFC, NFD, NFKC, and NFKD, and the algorithms to be
used for converting a string to each of these forms, are defined in
The motivation for normalization form FULLYNORMALIZED is explained in
A string is
A composing character is a character that is one or both of the following:
the second character in the canonical decomposition mapping of some
character that is not listed in the Composition Exclusion Table defined in
of nonzero canonical combining class (as defined in
A string is converted to FULLYNORMALIZED form as follows:
if the first character in the string is a composing character, prepend a single space (x20);
convert the resulting string to normalization form NFC.
Conforming implementations
It is fn:normalizeunicode
function leaves such codepoints
unchanged. If the implementation supports the requested normalization form then
it
A $normalizationForm
argument is not one of the values supported by the
implementation.
Converts a string to upper case.
This function is
If the value of $arg
is the empty sequence, the zerolength string is
returned.
Otherwise, the function returns the value of $arg
after translating every
Case mappings may change the length of a string. In general, the
fn:uppercase
and fn:lowercase
functions are not inverses
of each other: fn:lowercase(fn:uppercase($arg))
is not guaranteed to
return $arg
, nor is fn:uppercase(fn:lowercase($arg))
. The
Latin small letter dotless i (as used in Turkish) is perhaps the most prominent
lowercase letter which will not roundtrip. The Latin capital letter i with dot above
is the most prominent uppercase letter which will not round trip; there are others,
such as Latin capital letter Sharp S (#1E9E) which is introduced in Unicode 5.1.
These functions may not always be linguistically appropriate (e.g. Turkish i without dot) or appropriate for the application (e.g. titlecase). In cases such as Turkish, a simple translation should be used first.
Because the function is not sensitive to locale, results will not always match user expectations. In Quebec, for example, the standard uppercase equivalent of "è" is "È", while in metropolitan France it is more commonly "E"; only one of these is supported by the functions as defined.
Many characters of class Ll lack uppercase equivalents in the Unicode case mapping tables; many characters of class Lu lack lowercase equivalents.
The expression fn:uppercase("abCd0")
returns "ABCD0"
.
Converts a string to lower case.
This function is
If the value of $arg
is the empty sequence, the zerolength string is
returned.
Otherwise, the function returns the value of $arg
after translating every
Case mappings may change the length of a string. In general, the
fn:uppercase
and fn:lowercase
functions are not inverses
of each other: fn:lowercase(fn:uppercase($arg))
is not guaranteed to
return $arg
, nor is fn:uppercase(fn:lowercase($arg))
. The
Latin small letter dotless i (as used in Turkish) is perhaps the most prominent
lowercase letter which will not roundtrip. The Latin capital letter i with dot above
is the most prominent uppercase letter which will not round trip; there are others,
such as Latin capital letter Sharp S (#1E9E) which is introduced in Unicode 5.1.
These functions may not always be linguistically appropriate (e.g. Turkish i without dot) or appropriate for the application (e.g. titlecase). In cases such as Turkish, a simple translation should be used first.
Because the function is not sensitive to locale, results will not always match user expectations. In Quebec, for example, the standard uppercase equivalent of "è" is "È", while in metropolitan France it is more commonly "E"; only one of these is supported by the functions as defined.
Many characters of class Ll lack uppercase equivalents in the Unicode case mapping tables; many characters of class Lu lack lowercase equivalents.
The expression fn:lowercase("ABc!D")
returns "abc!d"
.
Returns the value of $arg
modified by replacing or removing
individual characters.
This function is
If the value of $arg
is the empty sequence, the function returns the
zerolength string.
Otherwise, the function returns a result string constructed by processing each $arg
, in order,
according to the following rules:
If the character does not appear in the value of $mapString
then it
is added to the result string unchanged.
If the character first appears in the value of $mapString
at some
position $transString
is
$transString
is added to the result string.
If the character first appears in the value of $mapString
at some
position $transString
is less than
If $mapString
is the zerolength string then the function returns
$arg
unchanged.
If a character occurs more than once in $mapString
, then the first
occurrence determines the action taken.
If $transString
is longer than $mapString
, the excess
characters are ignored.
The expression fn:translate("bar","abc","ABC")
returns "BAr"
.
The expression fn:translate("aaa","abc","ABC")
returns "AAA"
.
The expression fn:translate("abcdabc", "abc", "AB")
returns "ABdAB"
.
The functions described in the section examine a string $arg1
to see
whether it contains another string $arg2
as a substring. The result
depends on whether $arg2
is a substring of $arg1
, and
if so, on the range of $arg1
which $arg2
matches.
When the $arg1
contains a
contiguous sequence of characters whose $arg2
.
When a collation is specified, the rules are more complex.
All collations support the capability of deciding whether two fn:compare
, this is
all that is required. For other functions, such as fn:contains
,
the collation needs to support an additional property: it must be able to
decompose the string into a sequence of collation units, each unit consisting of
one or more characters, such that two strings can be compared by pairwise
comparison of these units. ("collation unit" is equivalent to "collation
element" as defined in $arg1
is then considered to contain $arg2
as a
substring if the sequence of collation units corresponding to $arg2
is a subsequence of the sequence of the collation units corresponding to
$arg1
. The characters in $arg1
that match are the
characters corresponding to these collation units.
This rule may occasionally lead to surprises. For example, consider a collation
that treats "Jaeger" and "Jäger" as equal. It might do this by
treating "ä" as representing two collation units, in which case the
expression fn:contains("Jäger", "eg")
will return
true
. Alternatively, a collation might treat "ae" as a single
collation unit, in which case the expression fn:contains("Jaeger",
"eg")
will return false
. The results of these functions thus
depend strongly on the properties of the collation that is used.
In addition,
collations may specify that some collation units should be ignored during matching. If hyphen is an ignored
collation unit, then fn:contains("codepoint", "codepoint")
will be true,
and fn:contains("codepoint", "")
will also be true.
In the definitions below, we refer to the terms
C is the collation; that is, the value of the $collation
argument if specified, otherwise the default collation.
P is the (candidate) substring $arg2
Q is the (candidate) containing string $arg1
The boundary condition B is satisfied at the start and end of a
string, and between any two characters that belong to different collation units
("collation elements" in the language of
It is possible to define collations that do not have the ability to decompose a
string into units suitable for substring matching. An argument to a function
defined in this section may be a URI that identifies a collation that is able to
compare two strings, but that does not have the capability to split the string
into collation units. Such a collation may cause the function to fail, or to
give unexpected results or it may be rejected as an unsuitable argument. The
ability to decompose strings into collation units is an
Function  Meaning 

fn:contains  Returns true if the string $arg1 contains $arg2 as a
substring, taking collations into account. 
fn:startswith  Returns true if the string $arg1 contains $arg2 as a
leading substring, taking collations into account. 
fn:endswith  Returns true if the string $arg1 contains $arg2 as a
trailing substring, taking collations into account. 
fn:substringbefore  Returns the part of $arg1 that precedes the first occurrence of
$arg2 , taking collations into account. 
fn:substringafter  Returns the part of $arg1 that follows the first occurrence of
$arg2 , taking collations into account. 
Returns true if the string $arg1
contains $arg2
as a
substring, taking collations into account.
The twoargument form of this function is
The threeargument form of this function is
If the value of $arg1
or $arg2
is the empty sequence, or
contains only ignorable collation units, it is interpreted as the zerolength
string.
If the value of $arg2
is the zerolength string, then the function returns
true
.
If the value of $arg1
is the zerolength string, the function returns
false
.
The collation used by this function is determined according to the rules in
The function returns an xs:boolean
indicating whether or not the value of
$arg1
contains (at the beginning, at the end, or anywhere within) at
least one sequence of collation units that provides a $arg2
, according to the collation that is
used.
A
The collation used in these examples, http://example.com/CollationA
is a
collation in which both "" and "*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation element" in
The expression fn:contains ( "tattoo", "t")
returns true()
.
The expression fn:contains ( "tattoo", "ttt")
returns false()
.
The expression fn:contains ( "", ())
returns true()
.
The expression fn:contains ( "abcdefghi", "def",
"http://example.com/CollationA")
returns true()
.
The expression fn:contains ( "a*b*c*d*e*f*g*h*i*", "def",
"http://example.com/CollationA")
returns true()
.
The expression fn:contains ( "abcd***ef**ghi", "def",
"http://example.com/CollationA")
returns true()
.
The expression fn:contains ( (), "****",
"http://example.com/CollationA")
returns true()
.
Returns true if the string $arg1
contains $arg2
as a
leading substring, taking collations into account.
The twoargument form of this function is
The threeargument form of this function is
If the value of $arg1
or $arg2
is the empty sequence, or
contains only ignorable collation units, it is interpreted as the zerolength
string.
If the value of $arg2
is the zerolength string, then the function returns
true
. If the value of $arg1
is the zerolength string and
the value of $arg2
is not the zerolength string, then the function returns
false
.
The collation used by this function is determined according to the rules in
The function returns an xs:boolean
indicating whether or not the value of
$arg1
starts with a sequence of collation units that provides a
$arg2
according to the
collation that is used.
A
The collation used in these examples, http://example.com/CollationA
is a
collation in which both "" and "*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation element" in
The expression fn:startswith("tattoo", "tat")
returns true()
.
The expression fn:startswith ( "tattoo", "att")
returns false()
.
The expression fn:startswith ((), ())
returns true()
.
The expression fn:startswith ( "abcdefghi", "abc",
"http://example.com/CollationA")
returns true()
.
The expression fn:startswith ( "a*b*c*d*e*f*g*h*i*", "abc",
"http://example.com/CollationA")
returns true()
.
The expression fn:startswith ( "abcd***ef**ghi", "abcdef",
"http://example.com/CollationA")
returns true()
.
The expression fn:startswith ( (), "****",
"http://example.com/CollationA")
returns true()
.
The expression fn:startswith ( "abcdefghi", "abc",
"http://example.com/CollationA")
returns true()
.
Returns true if the string $arg1
contains $arg2
as a
trailing substring, taking collations into account.
The twoargument form of this function is
The threeargument form of this function is
If the value of $arg1
or $arg2
is the empty sequence, or
contains only ignorable collation units, it is interpreted as the zerolength
string.
If the value of $arg2
is the zerolength string, then the function returns
true
. If the value of $arg1
is the zerolength string and
the value of $arg2
is not the zerolength string, then the function returns
false
.
The collation used by this function is determined according to the rules in
The function returns an xs:boolean
indicating whether or not the value of
$arg1
starts with a sequence of collation units that provides a
$arg2
according to the
collation that is used.
A
The collation used in these examples, http://example.com/CollationA
is a
collation in which both "" and "*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation element" in
The expression fn:endswith ( "tattoo", "tattoo")
returns true()
.
The expression fn:endswith ( "tattoo", "atto")
returns false()
.
The expression fn:endswith ((), ())
returns true()
.
The expression fn:endswith ( "abcdefghi", "ghi",
"http://example.com/CollationA")
returns true()
.
The expression fn:endswith ( "abcd***ef**ghi", "defghi",
"http://example.com/CollationA")
returns true()
.
The expression fn:endswith ( "abcd***ef**ghi", "defghi",
"http://example.com/CollationA")
returns true()
.
The expression fn:endswith ( (), "****",
"http://example.com/CollationA")
returns true()
.
The expression fn:endswith ( "abcdefghi", "ghi",
"http://example.com/CollationA")
returns true()
.
Returns the part of $arg1
that precedes the first occurrence of
$arg2
, taking collations into account.
The twoargument form of this function is
The threeargument form of this function is
If the value of $arg1
or $arg2
is the empty sequence, or
contains only ignorable collation units, it is interpreted as the zerolength
string.
If the value of $arg2
is the zerolength string, then the function returns
the zerolength string.
If the value of $arg1
does not contain a string that is equal to the value
of $arg2
, then the function returns the zerolength string.
The collation used by this function is determined according to the rules in
The function returns the substring of the value of $arg1
that precedes in
the value of $arg1
the first occurrence of a sequence of collation units
that provides a $arg2
according to the collation that is used.
A
The collation used in these examples, http://example.com/CollationA
is a
collation in which both "" and "*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation element" in
The expression fn:substringbefore ( "tattoo", "attoo")
returns "t"
.
The expression fn:substringbefore ( "tattoo", "tatto")
returns ""
.
The expression fn:substringbefore ((), ())
returns ""
.
The expression fn:substringbefore ( "abcdefghi", "de",
"http://example.com/CollationA")
returns "abc"
.
The expression fn:substringbefore ( "abcdefghi", "de",
"http://example.com/CollationA")
returns "abc"
.
The expression fn:substringbefore ( "a*b*c*d*e*f*g*h*i*", "***cde",
"http://example.com/CollationA")
returns "a*b*"
.
The expression fn:substringbefore ( "Eureka!", "****",
"http://example.com/CollationA")
returns ""
.
Returns the part of $arg1
that follows the first occurrence of
$arg2
, taking collations into account.
The twoargument form of this function is
The threeargument form of this function is
If the value of $arg1
or $arg2
is the empty sequence, or
contains only ignorable collation units, it is interpreted as the zerolength
string.
If the value of $arg2
is the zerolength string, then the function returns
the value of $arg1
.
If the value of $arg1
does not contain a string that is equal to the value
of $arg2
, then the function returns the zerolength string.
The collation used by this function is determined according to the rules in
The function returns the substring of the value of $arg1
that follows in
the value of $arg1
the first occurrence of a sequence of collation units
that provides a $arg2
according to the collation that is used.
A
The collation used in these examples, http://example.com/CollationA
is a
collation in which both "" and "*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation element" in
The expression fn:substringafter("tattoo", "tat")
returns "too"
.
The expression fn:substringafter("tattoo", "tattoo")
returns ""
.
The expression fn:substringafter((), ())
returns ""
.
The expression fn:substringafter("abcdefghi", "de",
"http://example.com/CollationA")
returns "fghi"
.
The expression fn:substringafter("abcdefghi", "de",
"http://example.com/CollationA")
returns "fghi"
.
The expression fn:substringafter ( "a*b*c*d*e*f*g*h*i*", "***cde***",
"http://example.com/CollationA")
returns "*f*g*h*i*"
.
The expression fn:substringafter ( "Eureka!", "****",
"http://example.com/CollationA")
returns "Eureka!"
.
The three functions described in this section make use of a regular expression syntax for pattern matching. This is described below.
Function  Meaning 

fn:matches  Returns true if the supplied string matches a given regular expression. 
fn:replace  Returns a string produced from the input string by replacing any substrings that match a given regular expression with a supplied replacement string. 
fn:tokenize  Returns a sequence of strings constructed by splitting the input wherever a separator is found; the separator is any substring that matches a given regular expression. 
fn:analyzestring  Analyzes a string using a regular expression, returning an XML structure that identifies which parts of the input string matched or failed to match the regular expression, and in the case of matched substrings, which substrings matched each capturing group in the regular expression. 
The regular expression syntax used by these functions is defined in terms of
the regular expression syntax specified in XML Schema (see
It is recommended that implementers consult
The regular expression syntax and semantics are identical to those
defined in
Two metacharacters, ^
and $
are
added. By default, the metacharacter ^
matches the
start of the entire string, while $
matches the end
of the entire string. In multiline mode, ^
matches
the start of any line (that is, the start of the entire string,
and the position immediately after a newline character), while
$
matches the end of any line (that is, the end of
the entire string, and the position immediately before a newline
character). Newline here means the character #x0A
only.
This means that the production in
[10] Char ::= [^.\?*+()#x5B#x5D]
is modified to read:
[10] Char ::= [^.\?*+{}()^$#x5B#x5D]
The XSD 1.1 grammar for regular expressions uses the same
production rule, but renumbered and renamed [73] NormalChar
; it
is affected in the same way.
The characters #x5B
and #x5D
correspond
to "[
" and "]
" respectively.
The definition of Char (production [10]) in
The following production:
[11] charClass ::= charClassEsc  charClassExpr  WildCardEsc
is modified to read:
[11] charClass ::= charClassEsc  charClassExpr 
WildCardEsc  "^"  "$"
Using XSD 1.1 as the baseline the equivalent is to change the production:
[74] charClass ::= SingleCharEsc  charClassEsc  charClassExpr  WildCardEsc
to read:
[74] charClass ::= SingleCharEsc  charClassEsc  charClassExpr 
WildCardEsc  "^"  "$"
following a quantifier. Specifically:?
X??
matches X, once or not at all
X*?
matches X, zero or more times
X+?
matches X, one or more times
X{n}?
matches X, exactly n times
X{n,}?
matches X, at least n times
X{n,m}?
matches X, at least n times, but
not more than m times
The effect of these quantifiers is that the regular expression
matches the
, the regular expression matches the
?
To achieve this, the production in
[4] quantifier ::= [?*+]  ( '{' quantity '}' )
is changed to:
[4] quantifier ::= ( [?*+]  ( '{' quantity '}' ) ) '?'?
(In the XSD 1.1 version of the regular expression grammar, this rule is unchanged, but is renumbered [67])
Reluctant quantifiers have no effect on the results of the
boolean fn:matches
function, since this
function is only interested in discovering whether a match
exists, and not where it exists.
Subexpressions (groups) within the regular expression are
recognized. The regular expression syntax defined by fn:replace
function) allow access to the parts of the
input string that matched a subexpression (called captured substrings).
When parentheses are used in a part of the regular expression that is matched
more than once (because it is within a construct that allows repetition), then
only the last substring that it matched will be captured. Note that this rule
is not sufficient in all cases to ensure an unambiguous result, especially in
cases where (a) the regular expression contains nested repeating constructs,
and/or (b) the repeating construct matches a zerolength string. In such cases
it is implementationdependent which substring is captured. For example given
the regular expression (a*)+
and the input string "aaaa"
, an implementation
might legitimately capture either "aaaa"
or a zero length string as the content
of the captured subgroup.
Noncapturing groups are also recognized. These are indicated
by the syntax (?:xxxx)
. The production rule for atom
in
( '(' regExp ')' )
with:
( '(' '?:'? regExp ')' )
(For the new versions of the XSD 1.0 and XSD 1.1 production rules for
atom
, see below.)
The presence of the optional ?:
has no effect on the set of strings
that match the regular expression, but causes the left parenthesis not to be counted
by operations that number the groups within a regular expression, for example the
fn:replace
function.
Backreferences are allowed
\N
where
N
is a single digit is always recognized as a
backreference; if this is followed by further digits, these
digits are taken to be part of the backreference if and only if
NN
is such that
the backreference is preceded by NN
or more unescaped opening
parentheses.
The regular expression is invalid if a backreference refers to a
subexpression that does not exist or whose
closing right parenthesis occurs after the backreference.
A backreference matches the string that was
matched by the N
th capturing subexpression within the regular
expression, that is, the parenthesized subexpression whose
opening left parenthesis is the N
th unescaped left
parenthesis within the regular expression.
For example, the regular expression
('").*\1
matches a sequence of characters
delimited either by an apostrophe at the start and end, or by a
quotation mark at the start and end.
If no string is matched by the N
th capturing
subexpression, the backreference is interpreted as matching
a zerolength string.
Combining this change with the introduction of noncapturing groups (see above), backreferences change the following production:
[9] atom ::= Char  charClass  ( '(' regExp ')' )
to
[9] atom ::= Char  charClass  ( '(' '?:'? regExp ')' )  backReference
[9a] backReference ::= "\" [19][09]*
With respect to the XSD 1.1 version of the regular expression grammar, the effect is to change:
[72] atom ::= NormalChar  charClass  ( '(' regExp ')' )
to
[72] atom ::= NormalChar  charClass  ( '(' '?:'? regExp ')' )  backReference
[72a] backReference ::= "\" [19][09]*
\
followed by a digit is invalid.
Some other regular expression languages interpret this as an octal character reference.
Single character escapes are extended to allow the
$
character to be escaped. The following production
is changed:
[24]SingleCharEsc ::= '\' [nrt\.?*+(){}#x2D#x5B#x5D#x5E]
to
[24]SingleCharEsc ::= '\' [nrt\.?*+(){}$#x2D#x5B#x5D#x5E]
(In the XSD 1.1 version of the regular expression grammar, the production rule
for SingleCharEsc
is unchanged, but is renumbered [84])
In
All these functions provide an optional parameter, $flags
,
to set options for the interpretation of the regular expression. The
parameter accepts a xs:string
, in which individual letters
are used to set options. The presence of a letter within the string
indicates that the option is on; its absence indicates that the option
is off. Letters may appear in any order and may be repeated. If there
are characters present that are not defined here as flags, then a
The following options are defined:
s
: If present, the match operates in "dotall"
mode. (Perl calls this the singleline mode.) If the
s
flag is not specified, the metacharacter
.
matches any character except a newline
(#x0A
) #x0D
)
.
matches any character whatsoever.
Suppose the input contains "hello" and "world" on two lines.
This will not be matched by the regular expression
"hello.*world" unless dotall mode is enabled.
m
: If present, the match operates in multiline
mode. By default, the metacharacter ^
matches the
start of the entire string, while $ matches the end of the
entire string. In multiline mode, ^
matches the
start of any line (that is, the start of the entire string, and
the position immediately after a newline character
$
matches the end of any line
#x0A
only.
i
: If present, the match operates in
caseinsensitive mode. The detailed rules are as follows.
In these
rules, a character C2 is considered to be a true
when the two characters
are considered as strings of length one, and the
fn:lowercase(C1) eq fn:lowercase(C2) or
fn:uppercase(C1) eq fn:uppercase(C2)
Note that the casevariants of a character under this definition are always single characters.
When a normal character (Char
) is used as an atom,
it represents
the set containing that character and all its casevariants.
For example, the regular expression "z" will match both "z" and
"Z".
A character range (charRange
in the XSD 1.0 grammar, replaced by productions charRange
and singleChar
in XSD 1.1i
" flag, together with their casevariants.
For example,
the regular expression "[AZ]" will match all
the letters AZ and all the letters az. It will also match
certain other characters such as #x212A
(KELVIN SIGN), since
fn:lowercase("#x212A")
is "k".
This rule applies also to a character range used in a character
class subtraction (charClassSub
): thus [AZ[IO]] will match
characters such as "A", "B", "a", and "b", but will not match
"I", "O", "i", or "o".
The rule also applies to a character range used as part of a negative character group: thus [^Q] will match every character except "Q" and "q" (these being the only casevariants of "Q" in Unicode).
A backreference is compared using caseblind comparison:
that is, each character must either be the same as the
corresponding character of the previously matched string, or must
be a casevariant of that character. For example, the strings
"Mum", "mom", "Dad", and "DUD" all match the regular
expression "([md])[aeiou]\1" when the "i
" flag is used.
All other constructs are unaffected by the "i
" flag.
For example,
"\p{Lu}" continues to match uppercase letters only.
x
: If present, whitespace characters
(#x9, #xA, #xD and #x20) in the regular
expression are removed prior to matching with one exception:
whitespace characters within character class expressions
(charClassExpr
) are not removed. This flag can be used,
for example, to break up long regular expressions into readable lines.
Examples:
fn:matches("helloworld", "hello world", "x")
returns true()
fn:matches("helloworld", "hello[ ]world", "x")
returns false()
fn:matches("hello world", "hello\ sworld", "x")
returns true()
fn:matches("hello world", "hello world", "x")
returns false()
q
: if present, all characters in the regular expression
are treated as representing themselves, not as metacharacters. In effect, every
character that would normally have a special meaning in a regular expression is implicitly escaped
by preceding it with a backslash.
Furthermore, when this flag is present, the characters $
and
\
have no special significance when used in the replacement string
supplied to the fn:replace
function.
This flag can be used in conjunction with the i
flag. If it is used
together with the m
, s
, or x
flag, that flag
has no effect.
Examples:
fn:tokenize("12.3.5.6", ".", "q")
returns ("12", "3", "5", "6")
fn:replace("a\b\c", "\", "\\", "q")
returns "a\\b\\c"
fn:replace("a/b/c", "/", "$", "q")
returns "a$b$c"
fn:matches("abcd", ".*", "q")
returns false()
fn:matches("Mr. B. Obama", "B. OBAMA", "iq")
returns true()
Returns true if the supplied string matches a given regular expression.
This function is
The effect of calling the first version of this function (omitting the argument
$flags
) is the same as the effect of calling the second version with the
$flags
argument set to a zerolength string. Flags are defined in
If $input
is the empty sequence, it is interpreted as the zerolength
string.
The function returns true
if $input
or some substring of
$input
matches the regular expression supplied as $pattern
.
Otherwise, the function returns false
. The matching rules are influenced by
the value of $flags
if present.
A $pattern
is invalid according to the rules described in
A $flags
is invalid according to the rules described in
Unless the metacharacters ^
and $
are used as anchors, the
string is considered to match the pattern if any substring matches the pattern. But if
anchors are used, the anchors must match the start/end of the string (in string mode),
or the start/end of a line (in multiline mode).
This is different from the behavior of patterns in
Regular expression matching is defined on the basis of Unicode code points; it takes no account of collations.
The expression fn:matches("abracadabra", "bra")
returns true()
.
The expression fn:matches("abracadabra", "^a.*a$")
returns true()
.
The expression fn:matches("abracadabra", "^bra")
returns false()
.
Given the source document:
let $poem
:=
the following function calls produce the following results, with the
poem
element as the context node:
The expression fn:matches($poem, "Kaum.*krähen")
returns false()
.
The expression fn:matches($poem, "Kaum.*krähen", "s")
returns true()
.
The expression fn:matches($poem, "^Kaum.*gesehen,$", "m")
returns true()
.
The expression fn:matches($poem, "^Kaum.*gesehen,$")
returns false()
.
The expression fn:matches($poem, "kiki", "i")
returns true()
.
Returns a string produced from the input string by replacing any substrings that match a given regular expression with a supplied replacement string.
This function is
The effect of calling the first version of this function (omitting the argument
$flags
) is the same as the effect of calling the second version with the
$flags
argument set to a zerolength string. Flags are defined in
The $flags
argument is interpreted in the same manner as for the
fn:matches
function.
If $input
is the empty sequence, it is interpreted as the zerolength
string.
The function returns the xs:string
that is obtained by replacing each
nonoverlapping substring of $input
that matches the given
$pattern
with an occurrence of the $replacement
string.
If two overlapping substrings of $input
both match the
$pattern
, then only the first one (that is, the one whose first $input
string) is
replaced.
If the q
flag is present, the replacement string is used
$replacement
string, a variable $N
may be used to refer to the substring captured by the
Nth parenthesized subexpression in the regular expression. For each match of the
pattern, these variables are assigned the value of the content matched by the relevant
subexpression, and the modified replacement string is then substituted for the $input
that matched the pattern.
$0
refers to the substring captured by the regular expression as a
whole.
More specifically, the rules are as follows, where S
is the number of
parenthesized subexpressions in the regular expression, and N
is the
decimal number formed by taking all the digits that consecutively follow the
$
character:
If N
=0
, then the variable is replaced by the substring
matched by the regular expression as a whole.
If 1
<=N
<=S
, then the variable is
replaced by the substring captured by the Nth parenthesized subexpression. If the
Nth
parenthesized subexpression was not matched, then the
variable is replaced by the zerolength string.
If S
<N
<=9
, then the variable is
replaced by the zerolength string.
Otherwise (if N
>S
and
N
>9
), the last digit of N
is taken to
be a literal character to be included "as is" in the replacement string, and the
rules are reapplied using the number N
formed by stripping off this
last digit.
For example, if the replacement string is
and there are 5 substrings, the result contains the value of the substring that
matches the second subexpression, followed by the digit $23
.3
Unless the q
flag is used, a literal $
character within the replacement string must be written as \$
, and a
literal \
character must be written as \\
.
If two alternatives within the pattern both match at the same position in the
$input
, then the match that is chosen is the one matched by the first
alternative. For example:
A $pattern
is invalid according to the rules described in section
A $flags
is invalid according to the rules described in section
A fn:matches("", $pattern,
$flags)
returns true
. It is not an error, however, if a captured
substring is zerolength.
A $replacement
contains a "$
" character that is not
immediately followed by a digit 09
and not immediately preceded by a
"\".
A $replacement
contains a "\
" character that is not part of a
"\\
" pair, unless it is immediately followed by a "$
"
character.
If the input string contains no substring that matches the regular expression, the result of the function is a single string identical to the input string.
The expression replace("abracadabra", "bra", "*")
returns "a*cada*"
.
The expression replace("abracadabra", "a.*a", "*")
returns "*"
.
The expression replace("abracadabra", "a.*?a", "*")
returns "*c*bra"
.
The expression replace("abracadabra", "a", "")
returns "brcdbr"
.
The expression replace("abracadabra", "a(.)", "a$1$1")
returns "abbraccaddabbra"
.
The expression replace("abracadabra", ".*?", "$1")
raises an error,
because the pattern matches the zerolength string
The expression replace("AAAA", "A+", "b")
returns "b"
.
The expression replace("AAAA", "A+?", "b")
returns "bbbb"
.
The expression replace("darted", "^(.*?)d(.*)$", "$1c$2")
returns "carted"
. d
is replaced.).
Returns a sequence of strings constructed by splitting the input wherever a separator is found; the separator is any substring that matches a given regular expression.
This function is
The effect of calling the first version of this function (omitting the argument
$flags
) is the same as the effect of calling the second version with the
$flags
argument set to a zerolength string. Flags are defined in
The $flags
argument is interpreted in the same way as for the
fn:matches
function.
If $input
is the empty sequence, or if $input
is the
zerolength string, the function returns the empty sequence.
The function returns a sequence of strings formed by breaking the $input
string into a sequence of strings, treating any substring that matches
$pattern
as a separator. The separators themselves are not returned.
If a separator occurs at the start of the $input
string, the result
sequence will start with a zerolength string. Zerolength strings will also occur in
the result sequence if a separator occurs at the end of the $input
string,
or if two adjacent substrings match the supplied $pattern
.
If two alternatives within the supplied $pattern
both match at the same
position in the $input
string, then the match that is chosen is the first.
For example:
A $pattern
is invalid according to the rules described in section
A $flags
is invalid according to the rules described in section
A $pattern
matches a zerolength string, that is, if fn:matches("",
$pattern, $flags)
returns true
.
If the input string is not zero length, and no separators are found in the input string, the result of the function is a single string identical to the input string.
The expression fn:tokenize("The cat sat on the mat", "\s+")
returns ("The", "cat", "sat", "on", "the", "mat")
.
The expression fn:tokenize("1, 15, 24, 50", ",\s*")
returns ("1", "15", "24", "50")
.
The expression fn:tokenize("1,15,,24,50,", ",")
returns ("1", "15", "", "24", "50", "")
.
fn:tokenize("abba", ".?")
raises the
The expression fn:tokenize("Some unparsed <br> HTML <BR> text",
"\s*<br>\s*", "i")
returns ("Some unparsed", "HTML", "text")
.
Analyzes a string using a regular expression, returning an XML structure that identifies which parts of the input string matched or failed to match the regular expression, and in the case of matched substrings, which substrings matched each capturing group in the regular expression.
This function is
The effect of calling the first version of this function (omitting the argument
$flags
) is the same as the effect of calling the second version with the
$flags
argument set to a zerolength string. Flags are defined in
The $flags
argument is interpreted in the same way as for the
fn:matches
function.
If $input
is the empty sequence the function behaves as if
$input
were the zerolength string. In this situation the result will be
an element node with no children.
The function returns an element node whose local name is
analyzestringresult
. This element and all its descendant elements have
the namespace URI http://www.w3.org/2005/xpathfunctions
. The namespace
prefix is fn:match
and fn:nonmatch
elements. This sequence
is formed by breaking the $input
string into a sequence of strings,
returning any substring that matches $pattern
as the content of a
match
element, and any intervening substring as the content of a
nonmatch
element.
More specifically, the function starts at the beginning of the input string and attempts
to find the first substring that matches the regular expression. If there are several
matches, the first match is defined to be the one whose starting position comes first in
the string. If several alternatives within the regular expression both match at the same
position in the input string, then the match that is chosen is the first alternative
that matches. For example, if the input string is The quick brown fox jumps
and the regular expression is jumpjumps
, then the match that is chosen is
jump
.
Having found the first match, the instruction proceeds to find the second and subsequent
matches by repeating the search, starting at the first
The input string is thus partitioned into a sequence of substrings, some of which match
the regular expression, others which do not match it. Each substring will contain at
least one character. This sequence is represented in the result by the sequence of
fn:match
and fn:nonmatch
children of the returned element
node; the string value of the fn:match
or fn:nonmatch
element
will be the corresponding substring of $input
, and the string value of the
returned element node will therefore be the same as $input
.
The content of an fn:nonmatch
element is always a single text node.
The content of a fn:match
element, however, is in general a sequence of
text nodes and fn:group
element children. An fn:group
element
with a nr
attribute having the integer value N identifies the
substring captured by the Nth parenthesized subexpression in the regular
expression. For each capturing subexpression there will be at most one corresponding
fn:group
element in each fn:match
element in the
result.
If the function is called twice with the same arguments, it is
The base URI of the element nodes in the result is
A schema is defined for the structure of the returned element, containing the
definitions below. The returned element and its descendants will have type annotations
obtained by validating the returned element against this schema, unless the function is
used in an environment where type annotations are not supported (for example, a Basic
XSLT Processor), in which case the elements will all be annotated as
xs:untyped
and the attributes as xs:untypedAtomic
.
A $pattern
is invalid according to the rules described in section
A $flags
is invalid according to the rules described in section
A $pattern
matches a zerolength string, that is, if fn:matches("",
$pattern, $flags)
returns true
.
The declarations and definitions in the above schema are not automatically
available in the static context of the fn:analyzestring
call (or of any other expression).
The contents of the static context are hostlanguage defined, and in some host languages are implementationdefined.
In the following examples, the result document is shown in serialized form, with whitespace between the element nodes. This whitespace is not actually present in the result.
The expression fn:analyzestring("The cat sat on the mat.", "\w+")
returns
<analyzestringresult xmlns="http://www.w3.org/2005/xpathfunctions">
<match>The</match>
<nonmatch> </nonmatch>
<match>cat</match>
<nonmatch> </nonmatch>
<match>sat</match>
<nonmatch> </nonmatch>
<match>on</match>
<nonmatch> </nonmatch>
<match>the</match>
<nonmatch> </nonmatch>
<match>mat</match>
<nonmatch>.</nonmatch>
</analyzestringresult>
.
The expression fn:analyzestring("20081203",
"^(\d+)\(\d+)\(\d+)$")
returns
<analyzestringresult xmlns="http://www.w3.org/2005/xpathfunctions">
<match><group nr="1">2008</group><group nr="2">12</group><group nr="3">03</group></match>
</analyzestringresult>
.
The expression fn:analyzestring("A1,C15,,D24, X50,",
"([AZ])([09]+)")
returns
<analyzestringresult xmlns="http://www.w3.org/2005/xpathfunctions">
<match><group nr="1">A</group><group nr="2">1</group></match>
<nonmatch>,</nonmatch>
<match><group nr="1">C</group><group nr="2">15</group></match>
<nonmatch>,,</nonmatch>
<match><group nr="1">D</group><group nr="2">24</group></match>
<nonmatch>, </nonmatch>
<match><group nr="1">X</group><group nr="2">50</group></match>
<nonmatch>,</nonmatch>
</analyzestringresult>
.
This section specifies functions that manipulate URI values, either as instances
of xs:anyURI
or as strings.
Function  Meaning 

fn:resolveuri  Resolves a relative IRI reference against an absolute IRI. 
fn:encodeforuri  Encodes reserved characters in a string that is intended to be used in the path segment of a URI. 
fn:iritouri  Converts a string containing an IRI into a URI according to the rules of

fn:escapehtmluri  Escapes a URI in the same way that HTML user agents handle attribute values expected to contain URIs. 
Resolves a relative IRI reference against an absolute IRI.
The oneargument form of this function is
The twoargument form of this function is
If the second argument is absent, the effect is the same as calling the twoargument
function with the value of fn:staticbaseuri()
as the second argument.
The function is defined to operate on IRI references as defined in
If $relative
is the empty sequence, the function returns the empty
sequence.
If $relative
is an absolute IRI (as defined above), then it is returned
unchanged.
Otherwise, the function resolves the relative IRI reference $relative
against the base IRI $base
using the algorithm defined in
The first form of this function resolves $relative
against the value of the
baseuri property from the static context. A
A $relative
is not a
valid IRI according to the rules of RFC3987, extended with an implementationdefined
subset of the extensions permitted in LEIRI, or if it is not a suitable relative
reference to use as input to the RFC3986 resolution algorithm extended to handle
additional unreserved characters.
A $base
is not a
valid IRI according to the rules of RFC3987, extended with an implementationdefined
subset of the extensions permitted in LEIRI, or if it is not a suitable IRI to use as
input to the chosen resolution algorithm (for example, if it is a relative IRI
reference, if it is a nonhierarchic URI, or if it contains a fragment identifier), then
.
A
Resolving a URI does not dereference it. This is merely a syntactic operation on two
The algorithms in the cited RFCs include some variations that are optional or recommended rather than mandatory; they also describe some common practices that are not recommended, but which are permitted for backwards compatibility. Where the cited RFCs permit variations in behavior, so does this specification.
Throughout this family of specifications, the phrase "resolving a relative URI (or IRI) reference" should be understood as using the rules of this function, unless otherwise stated.
Encodes reserved characters in a string that is intended to be used in the path segment of a URI.
This function is
If $uripart
is the empty sequence, the function returns the zerolength
string.
This function applies the URI escaping rules defined in section 2 of xs:string
supplied as $uripart
. The
effect of the function is to escape reserved characters. Each such character in the
string is replaced with its percentencoded form as described in
Since
All characters are escaped except those identified as "unreserved" by
This function escapes URI delimiters and therefore cannot be used indiscriminately to encode "invalid" characters in a path segment.
This function is invertible but not idempotent. This is because a string containing a
percent character will be modified by applying the function: for example
100%
becomes 100%25
, while 100%25
becomes
100%2525
.
The expression fn:encodeforuri("http://www.example.com/00/Weather/CA/Los%20Angeles#ocean")
returns "http%3A%2F%2Fwww.example.com%2F00%2FWeather%2FCA%2FLos%2520Angeles%23ocean"
.
The expression concat("http://www.example.com/",
encodeforuri("~bébé"))
returns "http://www.example.com/~b%C3%A9b%C3%A9"
.
The expression concat("http://www.example.com/", encodeforuri("100%
organic"))
returns "http://www.example.com/100%25%20organic"
.
Converts a string containing an IRI into a URI according to the rules of
This function is
If $iri
is the empty sequence, the function returns the zerolength
string.
Otherwise, the function converts the value of $iri
into a URI according to
the rules given in Section 3.1 of $iri
contains a character
that is invalid in an IRI, such as the space character (see note below), the invalid
character is replaced by its percentencoded form as described in
Since
The function is idempotent but not invertible. Both the inputs My Documents
and My%20Documents
will be converted to the output
My%20Documents
.
This function does not check whether $iri
is a valid IRI. It treats it as
an
The following printable ASCII characters are invalid in an IRI: "<", ">",
"
(double quote), space, "{", "}", "", "\", "^", and "`". Since these
characters should not appear in an IRI, if they do appear in $iri
they will
be percentencoded. In addition, characters outside the range x20
Since this function does not escape the PERCENT SIGN "%" and this character is not allowed in data within a URI, users wishing to convert character strings (such as file names) that include "%" to a URI should manually escape "%" by replacing it with "%25".
The expression fn:iritouri
("http://www.example.com/00/Weather/CA/Los%20Angeles#ocean")
returns "http://www.example.com/00/Weather/CA/Los%20Angeles#ocean"
.
The expression fn:iritouri ("http://www.example.com/~bébé")
returns "http://www.example.com/~b%C3%A9b%C3%A9"
.
Escapes a URI in the same way that HTML user agents handle attribute values expected to contain URIs.
This function is
If $uri
is the empty sequence, the function returns the zerolength
string.
Otherwise, the function escapes all $uri
to be escaped is replaced by an escape sequence, which is
formed by encoding the character as a sequence of octets in UTF8, and then representing
each of these octets in the form %HH, where HH is the hexadecimal representation of the
octet. This function must always generate hexadecimal values using the uppercase
letters AF.
The behavior of this function corresponds to the recommended handling of nonASCII
characters in URI attribute values as described in
The expression fn:escapehtmluri ("http://www.example.com/00/Weather/CA/Los
Angeles#ocean")
returns "http://www.example.com/00/Weather/CA/Los Angeles#ocean"
.
The expression fn:escapehtmluri ("javascript:if (navigator.browserLanguage ==
'fr') window.open('http://www.example.com/~bébé');")
returns "javascript:if (navigator.browserLanguage == 'fr')
window.open('http://www.example.com/~b%C3%A9b%C3%A9');"
.
This section defines functions and operators on the xs:boolean
datatype.
Since no literals are defined in XPath to reference the constant boolean values true and false, two functions are provided for the purpose.
Function  Meaning 

fn:true  Returns the xs:boolean value true . 
fn:false  Returns the xs:boolean value false . 
Returns the xs:boolean
value true
.
This function is
The result is equivalent to xs:boolean("1")
.
The expression fn:true()
returns xs:boolean(1)
.
Returns the xs:boolean
value false
.
This function is
The result is equivalent to xs:boolean("0")
.
The expression fn:false()
returns xs:boolean(0)
.
The following functions define the semantics of operators on boolean values in
Function  Meaning 

op:booleanequal  Returns true if the two arguments are the same boolean value. 
op:booleanlessthan  Returns true if the first argument is false and the second is true. 
op:booleangreaterthan  Returns true if the first argument is true and the second is false. 
The ordering operators op:booleanlessthan
and op:booleangreaterthan
are provided for application purposes
and for compatibility with xs:boolean
is not ordered.
Returns true
if the two arguments are the same boolean value.
Defines the semantics of the "eq"
operator on xs:boolean
values.
The function returns true
if both arguments are true
or if
both arguments are false
. It returns false
if one of the
arguments is true
and the other argument is false
.
Returns true if the first argument is false and the second is true.
Defines the
semantics of the "lt" operator on xs:boolean
values. Also used in the
definition of the "ge" operator.
The function returns true
if $arg1
is false
and
$arg2
is true
. Otherwise, it returns
false
.
Returns true if the first argument is true and the second is false.
Defines the
semantics of the "gt" operator on xs:boolean
values. Also used in the
definition of the "le" operator.
The function call op:booleangreaterthan($A, $B)
is defined to return the
same result as op:booleanlessthan($B, $A)
The following functions are defined on boolean values:
Function  Meaning 

fn:boolean  Computes the effective boolean value of the sequence $arg . 
fn:not  Returns true if the effective boolean value of $arg
is false , or false if it is true . 
Computes the effective boolean value of the sequence $arg
.
The function computes the effective boolean value of a sequence, defined according to
the following rules. See also
If $arg
is the empty sequence, fn:boolean
returns
false
.
If $arg
is a sequence whose first item is a node,
fn:boolean
returns true
.
If $arg
is a singleton value of type xs:boolean
or a
derived from xs:boolean
, fn:boolean
returns
$arg
.
If $arg
is a singleton value of type xs:string
or a type
derived from xs:string
, xs:anyURI
or a type derived from
xs:anyURI
or xs:untypedAtomic
,
fn:boolean
returns false
if the operand value has
zero length; otherwise it returns true
.
If $arg
is a singleton value of any numeric type or a type derived
from a numeric type, fn:boolean
returns false
if the
operand value is NaN
or is numerically equal to zero; otherwise it
returns true
.
In all other cases, fn:boolean
raises a type error
The static semantics of this function are described in [Formal Semantics].
The result of this function is not necessarily the same as $arg cast as
xs:boolean
. For example, fn:boolean("false")
returns the value
true
whereas "false" cast as xs:boolean
(which can also be
written xs:boolean("false")
) returns false
.
let $abc
:= ("a", "b", "")
fn:boolean($abc)
raises a type error
The expression fn:boolean($abc[1])
returns true()
.
The expression fn:boolean($abc[0])
returns false()
.
The expression fn:boolean($abc[3])
returns false()
.
Returns true
if the effective boolean value of $arg
is false
, or false
if it is true
.
This function is
The value of $arg
is first reduced to an effective boolean value by
applying the fn:boolean()
function. The function returns true
if the effective boolean value is false
, or false
if the
effective boolean value is true
.
The expression fn:not(fn:true())
returns false()
.
The expression fn:not("false")
returns false()
.
Operators are defined on the following type:
xs:duration
and on the two defined subtypes (see
xs:yearMonthDuration
xs:dayTimeDuration
No ordering relation is defined on xs:duration
values.
Two xs:duration
values may however be compared for equality.
Operations on durations (including equality comparison, casting to string, and extraction of components) all treat the duration as normalized. This means that the seconds and minutes components will always be less than 60, the hours component less than 24, and the months component less than 12. Thus, for example, a duration of 120 seconds always gives the same result as a duration of two minutes.
Conditions such as underflow and overflow may occur with arithmetic on
durations: see
This means that in practice, the information content of an xs:duration
value can be reduced to an xs:integer
number of months, and an xs:decimal
number of seconds. For the two defined subtypes this is further simplified so that one of these two
components is fixed at zero. Operations such as comparison of durations and arithmetic on durations
can be expressed in terms of numeric operations applied to these two components.
Two totally ordered subtypes of xs:duration
are defined in
These types were not defined in XSD 1.0, but they are defined in the current draft of XSD 1.1. The description given here is believed to be equivalent to that in XSD 1.1, and will become nonnormative when XSD 1.1 reaches Recommendation status.
[Definition] xs:yearMonthDuration
is derived from
xs:duration
by restricting its lexical representation to
contain only the year and month components. The value space of
xs:yearMonthDuration
is the set of xs:integer
month values. The year and month components of
xs:yearMonthDuration
correspond to the Gregorian year and
month components defined in section 5.5.3.2 of
The lexical representation for xs:yearMonthDuration
is the
xs:integer
.
An optional preceding minus sign ('') is allowed to indicate a negative
duration. If the sign is omitted a positive duration is indicated. To
indicate a xs:yearMonthDuration
of 1 year, 2 months, one
would write: P1Y2M. One could also indicate a
xs:yearMonthDuration
of minus 13 months as: P13M.
Reduced precision and truncated representations of this format are allowed provided they conform to the following:
If the number of years or months in any expression equals zero (0), the
number and its corresponding designator
The value of a xs:yearMonthDuration
lexical form is
obtained by multiplying the value of the years component by 12 and
adding the value of the months component. The value is positive or
negative depending on the preceding sign.
The canonical representation of xs:yearMonthDuration
restricts the value of the months component to xs:integer
values between 0 and 11, both inclusive. To convert from a noncanonical
representation to the canonical representation, the lexical
representation is first converted to a value in xs:integer
months as defined above. This value is then divided by 12 to obtain the
value of the years component of the canonical representation. The
remaining number of months is the value of the months component of the
canonical representation. For negative durations, the canonical form is
calculated using the absolute value of the duration and a negative sign
is prepended to it. If a component has the value zero (0), then the
number and the designator for that component
Let the function that calculates the value of an
xs:yearMonthDuration
in the manner described above be
called V(d). Then for two xs:yearMonthDuration
values x
and y, x > y if and only if V(x) > V(y). The order relation on
yearMonthDuration
is a total order.
[Definition] xs:dayTimeDuration
is derived from
xs:duration
by restricting its lexical representation to
contain only the days, hours, minutes and seconds components. The value
space of xs:dayTimeDuration
is the set of fractional second
values. The components of xs:dayTimeDuration
correspond to the
day, hour, minute and second components defined in Section 5.5.3.2 of
The lexical representation for xs:dayTimeDuration
is the
The values of the days, hours and minutes components are not restricted,
but allow an arbitrary unsigned xs:integer
. Similarly, the
value of the seconds component allows an arbitrary unsigned
xs:decimal
. An optional minus sign ('') is allowed to
precede the 'P', indicating a negative duration. If the sign is omitted,
the duration is positive. See also
For example, to indicate a duration of 3 days, 10 hours and 30 minutes, one would write: P3DT10H30M. One could also indicate a duration of minus 120 days as: P120D. Reduced precision and truncated representations of this format are allowed, provided they conform to the following:
If the number of days, hours, minutes, or seconds in any
expression equals zero (0), the number and its corresponding
designator
The seconds part
The designator 'T'
For example, P13D, PT47H, P3DT2H, PT35.89S and P4DT251M are all allowed. P134D is not allowed (invalid location of minus sign), although P134D is allowed.
The value of a xs:dayTimeDuration
lexical form in
fractional seconds is obtained by converting the days, hours, minutes
and seconds value to fractional seconds using the conversion rules: 24
hours = 1 day, 60 minutes = 1 hour and 60 seconds = 1 minute.
The canonical representation of xs:dayTimeDuration
restricts the value of the hours component to xs:integer
values between 0 and 23, both inclusive; the value of the minutes
component to xs:integer
values between 0 and 59; both
inclusive; and the value of the seconds component to
xs:decimal
valued from 0.0 to 59.999... (see
To convert from a noncanonical representation to the canonical
representation, the value of the lexical form in fractional seconds is
first calculated in the manner described above. The value of the days
component in the canonical form is then calculated by dividing the value
by 86,400 (24*60*60). The remainder is in fractional seconds. The value
of the hours component in the canonical form is calculated by dividing
this remainder by 3,600 (60*60). The remainder is again in fractional
seconds. The value of the minutes component in the canonical form is
calculated by dividing this remainder by 60. The remainder in fractional
seconds is the value of the seconds component in the canonical form. For
negative durations, the canonical form is calculated using the absolute
value of the duration and a negative sign is prepended to it. If a
component has the value zero (0) then the number and the designator for
that component must be omitted. However, if all the components of the
lexical form are zero (0), the canonical form is PT0S
.
Let the function that calculates the value of a
xs:dayTimeDuration
in the manner described above be called
xs:dayTimeDuration
values
xs:dayTimeDuration
is a total order.
Function  Meaning 

op:yearMonthDurationlessthan  Returns true if $arg1 is a shorter duration than
$arg2 . 
op:yearMonthDurationgreaterthan  Returns true if $arg1 is a longer duration than
$arg2 . 
op:dayTimeDurationlessthan  Returns true if $arg1 is a shorter duration than
$arg2 . 
op:dayTimeDurationgreaterthan  Returns true if $arg1 is a longer duration than
$arg2 . 
op:durationequal  Returns true if $arg1 and $arg2 are durations of the
same length. 
The following comparison operators are defined on the xs:boolean
result. As discussed in xs:duration
is a partial order rather than
a total order. For this reason, only equality is defined on xs:duration
.
A full complement of comparison and
arithmetic functions are defined on the two subtypes of duration described in
Returns true if $arg1
is a shorter duration than
$arg2
.
Defines
the semantics of the "lt" operator on xs:yearMonthDuration
values. Also used
in the definition of the "ge" operator.
If the number of months in the value of $arg1
is numerically less than the
number of months in the value of $arg2
, the function returns true.
Otherwise, the function returns false.
Either or both durations may be negative
Returns true if $arg1
is a longer duration than
$arg2
.
Defines
the semantics of the "gt" operator on xs:yearMonthDuration
values. Also used
in the definition of the "le" operator.
The function call op:yearMonthDurationgreaterthan($A, $B)
is defined to
return the same result as op:yearMonthDurationlessthan($B, $A)
Returns true if $arg1
is a shorter duration than
$arg2
.
Defines the
semantics of the "lt" operator on xs:dayTimeDuration
values. Also used in the
definition of the "ge" operator.
If the number of seconds in the value of $arg1
is numerically less than the
number of seconds in the value of $arg2
, the function returns true.
Otherwise, the function returns false.
Either or both durations may be negative
Returns true if $arg1
is a longer duration than
$arg2
.
Defines the
semantics of the "gt" operator on xs:dayTimeDuration
values. Also used in the
definition of the "le" operator.
The function call op:dayTimeDurationgreaterthan($A, $B)
is defined to
return the same result as op:dayTimeDurationlessthan($B, $A)
Returns true if $arg1
and $arg2
are durations of the
same length.
Defines the
semantics of the "eq" operators on xs:duration
values. Also used in the
definition of the "ne" operator.
If the xs:yearMonthDuration
components of $arg1
and
$arg2
are equal and the xs:dayTimeDuration
components of
$arg1
and $arg2
are equal, the function returns
true
.
Otherwise, the function returns false.
The semantics of this function are:
that is, the function returns true
if the months and seconds values of the
two durations are equal.
Note that this function, like any other, may be applied to arguments that are derived
from the types given in the function signature, including the two subtypes
xs:dayTimeDuration
and xs:yearMonthDuration
. With the
exception of the zerolength duration, no instance of xs:dayTimeDuration
can ever be equal to an instance of xs:yearMonthDuration
.
The expression op:durationequal(xs:duration("P1Y"),
xs:duration("P12M"))
returns true()
.
The expression op:durationequal(xs:duration("PT24H"),
xs:duration("P1D"))
returns true()
.
The expression op:durationequal(xs:duration("P1Y"),
xs:duration("P365D"))
returns false()
.
The expression op:durationequal(xs:yearMonthDuration("P0Y"),
xs:dayTimeDuration("P0D"))
returns true()
.
The expression op:durationequal(xs:yearMonthDuration("P1Y"),
xs:dayTimeDuration("P365D"))
returns false()
.
The expression op:durationequal(xs:yearMonthDuration("P2Y"),
xs:yearMonthDuration("P24M"))
returns true()
.
The expression op:durationequal(xs:dayTimeDuration("P10D"),
xs:dayTimeDuration("PT240H"))
returns true()
.
The expression op:durationequal(xs:duration("P2Y0M0DT0H0M0S"),
xs:yearMonthDuration("P24M"))
returns true()
.
The expression op:durationequal(xs:duration("P0Y0M10D"),
xs:dayTimeDuration("PT240H"))
returns true()
.
The duration datatype may be considered to be a composite datatypes
in that it contains distinct properties or components. The extraction functions specified
below extract a single component from a duration value.
For xs:duration
and its subtypes, including the two subtypes xs:yearMonthDuration
and
xs:dayTimeDuration
, the components are normalized: this means that the seconds and minutes
components will always be less than 60, the hours component less than 24, and the months component less than 12.
Function  Meaning 

fn:yearsfromduration  Returns the number of years in a duration. 
fn:monthsfromduration  Returns the number of months in a duration. 
fn:daysfromduration  Returns the number of days in a duration. 
fn:hoursfromduration  Returns the number of hours in a duration. 
fn:minutesfromduration  Returns the number of minutes in a duration. 
fn:secondsfromduration  Returns the number of seconds in a duration. 
Returns the number of years in a duration.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
representing the years
component in the value of $arg
. The result is obtained by casting
$arg
to an xs:yearMonthDuration
(see
If $arg
is a negative duration then the result will be negative..
If $arg
is an xs:dayTimeDuration
the function returns 0.
The expression fn:yearsfromduration(xs:yearMonthDuration("P20Y15M"))
returns 21
.
The expression fn:yearsfromduration(xs:yearMonthDuration("P15M"))
returns 1
.
The expression fn:yearsfromduration(xs:dayTimeDuration("P2DT15H"))
returns 0
.
Returns the number of months in a duration.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
representing the months
component in the value of $arg
. The result is obtained by casting
$arg
to an xs:yearMonthDuration
(see
If $arg
is a negative duration then the result will be negative..
If $arg
is an xs:dayTimeDuration
the function returns 0.
The expression fn:monthsfromduration(xs:yearMonthDuration("P20Y15M"))
returns 3
.
The expression fn:monthsfromduration(xs:yearMonthDuration("P20Y18M"))
returns 6
.
The expression fn:monthsfromduration(xs:dayTimeDuration("P2DT15H0M0S"))
returns 0
.
Returns the number of days in a duration.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
representing the days
component in the value of $arg
. The result is obtained by casting
$arg
to an xs:dayTimeDuration
(see
If $arg
is a negative duration then the result will be negative..
If $arg
is an xs:yearMonthDuration
the function returns 0.
The expression fn:daysfromduration(xs:dayTimeDuration("P3DT10H"))
returns 3
.
The expression fn:daysfromduration(xs:dayTimeDuration("P3DT55H"))
returns 5
.
The expression fn:daysfromduration(xs:yearMonthDuration("P3Y5M"))
returns 0
.
Returns the number of hours in a duration.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
representing the hours
component in the value of $arg
. The result is obtained by casting
$arg
to an xs:dayTimeDuration
(see
If $arg
is a negative duration then the result will be negative..
If $arg
is an xs:yearMonthDuration
the function returns 0.
The expression fn:hoursfromduration(xs:dayTimeDuration("P3DT10H"))
returns 10
.
The expression fn:hoursfromduration(xs:dayTimeDuration("P3DT12H32M12S"))
returns 12
.
The expression fn:hoursfromduration(xs:dayTimeDuration("PT123H"))
returns 3
.
The expression fn:hoursfromduration(xs:dayTimeDuration("P3DT10H"))
returns 10
.
Returns the number of minutes in a duration.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
representing the minutes
component in the value of $arg
. The result is obtained by casting
$arg
to an xs:dayTimeDuration
(see
If $arg
is a negative duration then the result will be negative..
If $arg
is an xs:yearMonthDuration
the function returns 0.
The expression fn:minutesfromduration(xs:dayTimeDuration("P3DT10H"))
returns 0
.
The expression fn:minutesfromduration(xs:dayTimeDuration("P5DT12H30M"))
returns 30
.
Returns the number of seconds in a duration.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:decimal
representing the seconds
component in the value of $arg
. The result is obtained by casting
$arg
to an xs:dayTimeDuration
(see
If $arg
is a negative duration then the result will be negative..
If $arg
is an xs:yearMonthDuration
the function returns 0.
The expression fn:secondsfromduration(xs:dayTimeDuration("P3DT10H12.5S"))
returns 12.5
.
The expression fn:secondsfromduration(xs:dayTimeDuration("PT256S"))
returns 16.0
.
Function  Meaning 

op:addyearMonthDurations  Returns the result of adding two xs:yearMonthDuration values. 
op:subtractyearMonthDurations  Returns the result of subtracting one xs:yearMonthDuration value
from another. 
op:multiplyyearMonthDuration  Returns the result of multiplying the value of
$arg1 by $arg2 . The result is rounded to the nearest
month. 
op:divideyearMonthDuration  Returns the result of dividing the value of
$arg1 by $arg2 . The result is rounded to the nearest
month. 
op:divideyearMonthDurationbyyearMonthDuration  Returns the ratio of two xs:yearMonthDuration values. 
op:adddayTimeDurations  Returns the sum of two xs:dayTimeDuration values. 
op:subtractdayTimeDurations  Returns the result of subtracting one xs:dayTimeDuration from
another. 
op:multiplydayTimeDuration  Returns the result of multiplying a xs:dayTimeDuration by a
number. 
op:dividedayTimeDuration  Returns the result of multiplying a xs:dayTimeDuration by a
number. 
op:dividedayTimeDurationbydayTimeDuration  Returns the ratio of two xs:dayTimeDuration values, as a decimal
number. 
For operators that combine a duration and a date/time value, see
Returns the result of adding two xs:yearMonthDuration
values.
Defines the semantics of the
"+" operator on xs:yearMonthDuration
values.
The function returns the result of adding the value of $arg1
to the value
of $arg2
. The result will be an xs:yearMonthDuration
whose
length in months is equal to the length in months of $arg1
plus the length
in months of $arg2
.
For handling of overflow, see
Either duration (and therefore the result) may be negative.
The expression op:addyearMonthDurations(xs:yearMonthDuration("P2Y11M"),
xs:yearMonthDuration("P3Y3M"))
returns xs:yearMonthDuration("P6Y2M")
.
Returns the result of subtracting one xs:yearMonthDuration
value
from another.
Defines the semantics of the
"" operator on xs:yearMonthDuration
values.
The function returns the result of subtracting the value of $arg2
from the
value of $arg1
. The result will be an xs:yearMonthDuration
whose length in months is equal to the length in months of $arg1
minus the
length in months of $arg2
.
For handling of overflow, see
Either duration (and therefore the result) may be negative.
The expression op:subtractyearMonthDurations(xs:yearMonthDuration("P2Y11M"),
xs:yearMonthDuration("P3Y3M"))
returns xs:yearMonthDuration("P4M")
.
Returns the result of multiplying the value of
$arg1
by $arg2
. The result is rounded to the nearest
month.
Defines the semantics of the
"*" operator on xs:yearMonthDuration
values.
The result is the xs:yearMonthDuration
whose length
in months is equal to the result of applying the fn:round
function to the
value obtained by multiplying the length in months of $arg1
by the value of
$arg2
.
If $arg2
is positive or negative zero, the result is a zerolength
duration. If $arg2
is positive or negative infinity, the result overflows
and is handled as discussed in
For handling of overflow and underflow, see
A $arg2
is
NaN
.
Either duration (and therefore the result) may be negative.
The expression op:multiplyyearMonthDuration(xs:yearMonthDuration("P2Y11M"),
2.3)
returns xs:yearMonthDuration("P6Y9M")
.
Returns the result of dividing the value of
$arg1
by $arg2
. The result is rounded to the nearest
month.
Defines the semantics of the
"div" operator on xs:yearMonthDuration
and numeric values.
The result is the xs:yearMonthDuration
whose length
in months is equal to the result of applying the fn:round
function to the
value obtained by dividing the length in months of $arg1
by the value of
$arg2
.
If $arg2
is positive or negative infinity, the result is a zerolength
duration. If $arg2
is positive or negative zero, the result overflows and
is handled as discussed in
For handling of overflow and underflow, see
A $arg2
is
NaN
.
Either operand (and therefore the result) may be negative.
The expression op:divideyearMonthDuration(xs:yearMonthDuration("P2Y11M"),
1.5)
returns xs:yearMonthDuration("P1Y11M")
.
Returns the ratio of two xs:yearMonthDuration
values.
Defines the semantics of the
"div" operator on xs:yearMonthDuration
values.
The function returns the result of dividing the length in months of $arg1
by the length in months of $arg2
, according to the rules of the
op:numericdivide
function for integer operands.
For handling of overflow and underflow, see
Either duration (and therefore the result) may be negative.
The expression op:divideyearMonthDurationbyyearMonthDuration(xs:yearMonthDuration("P3Y4M"),
xs:yearMonthDuration("P1Y4M"))
returns 2.5
.
The following example demonstrates how to calculate the length of an
xs:yearMonthDuration
value in months:
The expression op:divideyearMonthDurationbyyearMonthDuration(xs:yearMonthDuration("P3Y4M"),
xs:yearMonthDuration("P1M"))
returns 40
.
Returns the sum of two xs:dayTimeDuration
values.
Defines the semantics of the "+"
operator on xs:dayTimeDuration
values.
The function returns the result of adding the value of $arg1
to the value
of $arg2
. The result is the xs:dayTimeDuration
whose length in
seconds is equal to the sum of the length in seconds of the two input durations.
For handling of overflow, see
Either duration (and therefore the result) may be negative.
The expression op:adddayTimeDurations(xs:dayTimeDuration("P2DT12H5M"),
xs:dayTimeDuration("P5DT12H"))
returns xs:dayTimeDuration('P8DT5M')
.
Returns the result of subtracting one xs:dayTimeDuration
from
another.
Defines the semantics of the ""
operator on xs:dayTimeDuration
values.
The function returns the result of subtracting the value of $arg2
from the
value of $arg1
. The result is the xs:dayTimeDuration
whose
length in seconds is equal to the length in seconds of $arg1
minus the
length in seconds of $arg2
.
For handling of overflow, see
Either duration (and therefore the result) may be negative.
The expression op:subtractdayTimeDurations(xs:dayTimeDuration("P2DT12H"),
xs:dayTimeDuration("P1DT10H30M"))
returns xs:dayTimeDuration('P1DT1H30M')
.
Returns the result of multiplying a xs:dayTimeDuration
by a
number.
Defines the semantics of the "*"
operator on xs:dayTimeDuration
and numeric values.
The function returns the result of multiplying the value of $arg1
by
$arg2
. The result is the xs:dayTimeDuration
whose length in
seconds is equal to the length in seconds of $arg1
multiplied by the
numeric value $arg2
.
If $arg2
is positive or negative zero, the result is a zerolength
duration. If $arg2
is positive or negative infinity, the result overflows
and is handled as discussed in
For handling of overflow and underflow, see
A $arg2
is
NaN
.
Either operand (and therefore the result) may be negative.
The expression op:multiplydayTimeDuration(xs:dayTimeDuration("PT2H10M"),
2.1)
returns xs:dayTimeDuration('PT4H33M')
.
Returns the result of multiplying a xs:dayTimeDuration
by a
number.
Defines the semantics of the
"div" operator on xs:dayTimeDuration
values.
The function returns the result of dividing the value of $arg1
by
$arg2
. The result is the xs:dayTimeDuration
whose length in
seconds is equal to the length in seconds of $arg1
divided by the numeric
value $arg2
.
If $arg2
is positive or negative infinity, the result is a zerolength
duration. If $arg2
is positive or negative zero, the result overflows and
is handled as discussed in
For handling of overflow and underflow, see
A $arg2
is
NaN
.
Either operand (and therefore the result) may be negative.
The expression op:dividedayTimeDuration(xs:dayTimeDuration("P1DT2H30M10.5S"),
1.5)
returns xs:duration("PT17H40M7S")
.
Returns the ratio of two xs:dayTimeDuration
values, as a decimal
number.
Defines the semantics of the
"div" operator on xs:dayTimeDuration
values.
The function returns the result of dividing the value of $arg1
by
$arg2
. The result is the xs:dayTimeDuration
whose length in
seconds is equal to the length in seconds of $arg1
divided by the length in
seconds of $arg2
. The calculation is performed by applying
op:numericdivide
to the two xs:decimal
operands.
For handling of overflow and underflow, see
Either operand (and therefore the result) may be negative.
The expression fn:roundhalftoeven( op:dividedayTimeDurationbydayTimeDuration(
xs:dayTimeDuration("P2DT53M11S"), xs:dayTimeDuration("P1DT10H")),
4)
returns 1.4378
.
This examples shows how to determine the number of seconds in a duration.
The expression op:dividedayTimeDurationbydayTimeDuration(xs:dayTimeDuration("P2DT53M11S"),
xs:dayTimeDuration("PT1S"))
returns 175991.0
.
This section defines operations on the
See
The operators described in this section are defined on the following date and time types:
xs:dateTime
xs:date
xs:time
xs:gYearMonth
xs:gYear
xs:gMonthDay
xs:gMonth
xs:gDay
The only operations defined on
xs:gYearMonth
, xs:gYear
,
xs:gMonthDay
, xs:gMonth
and xs:gDay
values are equality comparison and component extraction.
For other types, further operations are provided, including order comparisons, arithmetic, formatted display, and timezone
adjustment.
For a number of the above datatypes
All
A processor that limits the number of digits in date and time datatype
representations may encounter overflow and underflow conditions when it
tries to execute the functions in
As defined in xs:dateTime
,
xs:date
, xs:time
, xs:gYearMonth
, xs:gYear
,
xs:gMonthDay
, xs:gMonth
, xs:gDay
values,
referred to collectively as date/time values, are represented as seven components or properties:
year
, month
, day
, hour
, minute
,
second
and timezone
. The first five components are
xs:integer
values. The value of the second
component is an xs:decimal
and the value of the timezone
component is an xs:dayTimeDuration
.
For all the primitive date/time datatypes, the timezone
property is optional and may or may not
be present. Depending on the datatype, some of the remaining six properties must be present and
some must be xs:dateTime
values, this local value
For xs:time
, 00:00:00
and 24:00:00
are alternate lexical forms
for the same value, whose canonical representation is 00:00:00
. For xs:dateTime
,
a time component 24:00:00
translates to 00:00:00
of the following day.
An xs:dateTime
with lexical
representation 19990531T05:00:00
is represented in the datamodel by {1999, 5, 31, 5, 0, 0.0, ()}
.
An xs:dateTime
with lexical
representation 19990531T13:20:0005:00
is represented by {1999, 5, 31, 13, 20, 0.0, PT5H}
.
An xs:dateTime
with lexical
representation 19991231T24:00:00
is represented by {2000, 1, 1, 0, 0, 0.0, ()}
.
An xs:date
with lexical
representation 20050228+8:00
is represented by {2005, 2, 28, (), (), (), PT8H}
.
An xs:time
with lexical
representation 24:00:00
is represented by {(), (), (), 0, 0, 0, ()}
.
A function is provided for constructing a
xs:dateTime
value from a xs:date
value and a
xs:time
value.
Returns an xs:dateTime
value created by combining an
xs:date
and an xs:time
.
This function is
If either $arg1
or $arg2
is the empty sequence the function
returns the empty sequence.
Otherwise, the function returns an xs:dateTime
whose date component is
equal to $arg1
and whose time component is equal to $arg2
.
The timezone of the result is computed as follows:
If neither argument has a timezone, the result has no timezone.
If exactly one of the arguments has a timezone, or if both arguments have the same timezone, the result has this timezone.
A
The expression fn:dateTime(xs:date("19991231"),
xs:time("12:00:00"))
returns xs:dateTime("19991231T12:00:00")
.
The expression fn:dateTime(xs:date("19991231"),
xs:time("24:00:00"))
returns xs:dateTime("19991231T00:00:00")
. "24:00:00"
is an alternate lexical form
for "00:00:00"
).
Function  Meaning 

op:dateTimeequal  Returns true if the two supplied xs:dateTime values refer to the
same instant in time. 
op:dateTimelessthan  Returns true if the first argument represents an earlier instant
in time than the second argument. 
op:dateTimegreaterthan  Returns true if the first argument represents a later instant in
time than the second argument. 
op:dateequal  Returns true if and only if the starting instants of the two
supplied xs:date values are the same. 
op:datelessthan  Returns true if and only if the starting instant of
$arg1 is less than the starting instant of $arg2 . Returns
false otherwise. 
op:dategreaterthan  Returns true if and only if the starting instant of
$arg1 is greater than the starting instant of $arg2 .
Returns false otherwise. 
op:timeequal  Returns true if the two xs:time values represent the
same instant in time, when treated as being times on the same date, before adjusting the
timezone. 
op:timelessthan  Returns true if the first xs:time value represents an
earlier instant in time than the second, when both are treated as being times on the
same date, before adjusting the timezone. 
op:timegreaterthan  Returns true if the first xs:time value represents a
later instant in time than the second, when both are treated as being times on the same
date, before adjusting the timezone. 
op:gYearMonthequal  Returns true if the two xs:gYearMonth values have the same
starting instant. 
op:gYearequal  Returns true if the two xs:gYear values have the same starting
instant. 
op:gMonthDayequal  Returns true if the two xs:gMonthDay values have the same starting
instant, when considered as days in the same year. 
op:gMonthequal  Returns true if the two xs:gMonth values have the same starting
instant, when considered as months in the same year. 
op:gDayequal  Returns true if the two xs:gDay values have the same starting
instant, when considered as days in the same month of the same year. 
The following comparison operators are defined on the xs:boolean
result.
An xs:dateTime
can be considered to consist of seven components:
year
, month
, day
, hour
, minute
,
second
and timezone
. For xs:dateTime
six components (year
,
month
, day
, hour
, minute
and second
) are required
and timezone
is optional. For other date/time values, of the first six components, some are required
and others must be Timezone
is always optional. For example, for xs:date
,
the year
, month
and day
components are required and hour
,
minute
and second
components must be absent; for xs:time
the hour
,
minute
and second
components are required and year
, month
and
day
are missing; for xs:gDay
, day
is required and year
,
month
, hour
, minute
and second
are missing.
In explicitTimezone
facet is available with values
optional
, required
, or prohibited
to
enable the timezone to be defined as mandatory or disallowed.
Values of the date/time datatypes xs:time
, xs:gMonthDay
, xs:gMonth
,
and xs:gDay
, can be considered to represent a sequence of recurring time instants or time periods.
An xs:time
occurs every day. An xs:gMonth
occurs every year. Comparison operators
on these datatypes compare the starting instants of equivalent occurrences in the recurring series.
These xs:dateTime
values are calculated as described below.
Comparison operators on xs:date
, xs:gYearMonth
and xs:gYear
compare
their starting instants. These xs:dateTime
values are calculated as described below.
The starting instant of an occurrence of a date/time value is an xs:dateTime
calculated by filling
in the missing components of the local value from a reference xs:dateTime
. An example of a suitable
reference xs:dateTime
is 19720101T00:00:00
. Then, for example, the starting
instant corresponding to the xs:date
value 20090312
is
20090312T00:00:00
; the starting instant corresponding to the xs:time
value
13:30:02
is 19720101T13:30:02
; and the starting instant corresponding to the
gMonthDay
value 0229
is 19720229T00:00:00
(which explains
why a leap year was chosen for the reference).
In the previous version of this specification, the reference date/time chosen was
19721231T00:00:00
. While this gives the same results, it produces a "starting instant" for
a gMonth
or gMonthDay
that bears no
relation to the ordinary meaning of the term, and it also required special handling of short months.
The original choice was made to allow for leap seconds; but since leap seconds are not recognized
in date/time arithmetic, this is not actually necessary.
If the xs:time
value written as
24:00:00
is to be compared, filling in the missing components gives 19720101T00:00:00
,
because 24:00:00
is an alternative representation of 00:00:00
(the lexical value
"24:00:00"
is
converted to the time components {0,0,0} before the missing components are filled
in). This has the consequence that when ordering xs:time
values,
24:00:00
is
considered to be earlier than 23:59:59
. However, when ordering
xs:dateTime
values, a time component of 24:00:00
is considered equivalent to 00:00:00
on the
following day.
Note that the reference xs:dateTime
does not have a timezone. The timezone
component
is never filled in from the reference xs:dateTime
. In some cases, if the date/time value does not
have a timezone, the implicit timezone from the dynamic context is used as the timezone.
This specification uses the reference xs:dateTime 19720101T00:00:00
in the description of the
comparison operators. Implementations may use other reference xs:dateTime
values
as long as they yield the same results. The reference xs:dateTime
used must meet the following
constraints: when it is used to supply components into xs:gMonthDay
values, the year must allow
for February 29 and so must be a leap year; when it is used to supply missing components into xs:gDay
values, the month must allow for 31 days. Different reference xs:dateTime
values may be used for
different operators.
Returns true if the two supplied xs:dateTime
values refer to the
same instant in time.
Defines the
semantics of the "eq" operator on xs:dateTime
values. Also used in the
definition of the "ne", "le" and "ge" operators.
This function is
If either $arg1
or $arg2
has no timezone component, the
effective value of the argument is obtained by substituting the implicit timezone from
the dynamic evaluation context.
The function then returns true
if and only if the effective value of
$arg1
is equal to the effective value of $arg2
according to
the algorithm defined in section 3.2.7.4 of Order relation on dateTime
for xs:dateTime
values with
timezones. Otherwise the function returns false
.
Assume that the dynamic context provides an implicit timezone value of
05:00
The expression op:dateTimeequal(xs:dateTime("20020402T12:00:0001:00"),
xs:dateTime("20020402T17:00:00+04:00"))
returns true()
.
The expression op:dateTimeequal(xs:dateTime("20020402T12:00:00"),
xs:dateTime("20020402T23:00:00+06:00"))
returns true()
.
The expression op:dateTimeequal(xs:dateTime("20020402T12:00:00"),
xs:dateTime("20020402T17:00:00"))
returns false()
.
The expression op:dateTimeequal(xs:dateTime("20020402T12:00:00"),
xs:dateTime("20020402T12:00:00"))
returns true()
.
The expression op:dateTimeequal(xs:dateTime("20020402T23:00:0004:00"),
xs:dateTime("20020403T02:00:0001:00"))
returns true()
.
The expression op:dateTimeequal(xs:dateTime("19991231T24:00:00"),
xs:dateTime("20000101T00:00:00"))
returns true()
.
The expression op:dateTimeequal(xs:dateTime("20050404T24:00:00"),
xs:dateTime("20050404T00:00:00"))
returns false()
.
Returns true
if the first argument represents an earlier instant
in time than the second argument.
Defines the
semantics of the "lt" operator on xs:dateTime
values. Also used in the
definition of the
This function is
If either $arg1
or $arg2
has no timezone component, the
effective value of the argument is obtained by substituting the implicit timezone from
the dynamic evaluation context.
The function then returns true
if and only if the effective value of
$arg1
is less than the effective value of $arg2
according
to the algorithm defined in section 3.2.7.4 of Order relation on dateTime
for xs:dateTime
values with
timezones. Otherwise the function returns false
.
Returns true
if the first argument represents a later instant in
time than the second argument.
Defines the
semantics of the "gt" operator on xs:dateTime
values. Also used in the
definition of the
This function is
The function call op:dateTimegreaterthan($A, $B)
is defined to return the
same result as op:dateTimelessthan($B, $A)
Returns true
if and only if the starting instants of the two
supplied xs:date
values are the same.
Defines the
semantics of the "eq" operator on xs:date
values. Also used in the definition
of the "ne", "le" and "ge" operators.
This function is
The starting instant of an xs:date
is the xs:dateTime
at time
00:00:00
on that date.
The function returns the result of the expression:
The expression op:dateequal(xs:date("20041225Z"),
xs:date("20041225+07:00"))
returns false()
. xs:dateTime("20041225T00:00:00Z")
and
xs:dateTime("20041225T00:00:00+07:00")
. These are normalized to
xs:dateTime("20041225T00:00:00Z")
and
xs:dateTime("20041224T17:00:00Z")
. ).
The expression op:dateequal(xs:date("2004122512:00"),
xs:date("20041226+12:00"))
returns true()
.
Returns true
if and only if the starting instant of
$arg1
is less than the starting instant of $arg2
. Returns
false
otherwise.
Defines the semantics
of the "lt" operator on xs:date
values. Also used in the definition of the
The starting instant of an xs:date
is the xs:dateTime
at time
00:00:00
on that date.
The function returns the result of the expression:
The expression op:datelessthan(xs:date("20041225Z"),
xs:date("2004122505:00"))
returns true()
.
The expression op:datelessthan(xs:date("2004122512:00"),
xs:date("20041226+12:00"))
returns false()
.
Returns true
if and only if the starting instant of
$arg1
is greater than the starting instant of $arg2
.
Returns false
otherwise.
Defines the semantics
of the "gt" operator on xs:date
values. Also used in the definition of the
This function is
The function call op:dategreaterthan($A, $B)
is defined to return the
same result as op:datelessthan($B, $A)
The expression op:dategreaterthan(xs:date("20041225Z"),
xs:date("20041225+07:00"))
returns true()
.
The expression op:dategreaterthan(xs:date("2004122512:00"),
xs:date("20041226+12:00"))
returns false()
.
Returns true
if the two xs:time
values represent the
same instant in time, when treated as being times on the same date, before adjusting the
timezone.
Defines the
semantics of the "eq" operator on xs:time
values. Also used in the definition
of the "ne", "le" and "ge" operators.
This function is
Each of the supplied xs:time
values is expanded to an
xs:dateTime
value by associating the time with an arbitrary date. The
function returns the result of comparing these two xs:dateTime
values using
op:dateTimeequal
.
The result of the function is thus the same as the value of the expression:
Assume that the date components from the reference xs:dateTime
correspond to 19721231
.
The expression op:timeequal(xs:time("08:00:00+09:00"),
xs:time("17:00:0006:00"))
returns false()
. xs:dateTime
s calculated using the reference date
components are 19721231T08:00:00+09:00
and
19721231T17:00:0006:00
. These normalize to
19721230T23:00:00Z
and 19721231T23:00:00Z
.
).
The expression op:timeequal(xs:time("21:30:00+10:30"),
xs:time("06:00:0005:00"))
returns true()
.
The expression op:timeequal(xs:time("24:00:00+01:00"),
xs:time("00:00:00+01:00"))
returns true()
. xs:dateTime
values, a time of 24:00:00
is equivalent to 00:00:00
on
the following day. For xs:time
, the normalization from
24:00:00
to 00:00:00
happens before the
xs:time
is converted into an xs:dateTime
for the
purpose of the equality comparison. For xs:time
, any operation on
24:00:00
produces the same result as the same operation on
00:00:00
because these are two different lexical representations
of the same value. ).
Returns true
if the first xs:time
value represents an
earlier instant in time than the second, when both are treated as being times on the
same date, before adjusting the timezone.
Defines the semantics
of the "lt" operator on xs:time
values. Also used in the definition of the
This function is
Each of the supplied xs:time
values is expanded to an
xs:dateTime
value by associating the time with an arbitrary date. The
function returns the result of comparing these two xs:dateTime
values using
op:dateTimelessthan
.
The result of the function is thus the same as the value of the expression:
Assume that the dynamic context provides an implicit timezone value of
05:00
.
The expression op:timelessthan(xs:time("12:00:00"),
xs:time("23:00:00+06:00"))
returns false()
.
The expression op:timelessthan(xs:time("11:00:00"),
xs:time("17:00:00Z"))
returns true()
.
The expression op:timelessthan(xs:time("23:59:59"),
xs:time("24:00:00"))
returns false()
.
Returns true
if the first xs:time
value represents a
later instant in time than the second, when both are treated as being times on the same
date, before adjusting the timezone.
Defines the semantics
of the "gt" operator on xs:time
values. Also used in the definition of the
This function is
The function call op:timegreaterthan($A, $B)
is defined to return the
same result as op:timelessthan($B, $A)
The expression op:timegreaterthan(xs:time("08:00:00+09:00"),
xs:time("17:00:0006:00"))
returns false()
.
Returns true if the two xs:gYearMonth
values have the same
starting instant.
Defines the
semantics of the "eq" operator on xs:gYearMonth
values. Also used in the
definition of the "ne" operator.
This function is
The starting instants of $arg1
and $arg2
are calculated by
supplying the missing components of $arg1
and $arg2
from the
xs:dateTime
template xxxxxx01T00:00:00
. The function
returns the result of comparing these two starting instants using
op:dateTimeequal
.
Assume that the dynamic context provides an implicit timezone value of
05:00
.
op:gYearMonthequal(xs:gYearMonth("198602"), xs:gYearMonth("198603"))
returns false()
. The starting instants are
19860201T00:00:0005:00
and 19860301T00:00:00
,
respectively.
op:gYearMonthequal(xs:gYearMonth("197803"), xs:gYearMonth("198603Z"))
returns false()
. The starting instants are
19780301T00:00:0005:00
and 19860301T00:00:00Z
,
respectively.
Returns true if the two xs:gYear
values have the same starting
instant.
Defines the semantics
of the "eq" operator on xs:gYear
values. Also used in the definition of the
"ne" operator.
This function is
The starting instants of $arg1
and $arg2
are calculated by
supplying the missing components of $arg1
and $arg2
from the
xs:dateTime
template xxxx0101T00:00:00
. The function
returns the result of comparing these two starting instants using
op:dateTimeequal
.
Assume that the dynamic context provides an implicit timezone value of
05:00
. Assume, also, that the xs:dateTime
template is
xxxx0101T00:00:00
.
op:gYearequal(xs:gYear("200512:00"), xs:gYear("2005+12:00"))
returns
false()
. The starting instants are
20050101T00:00:0012:00
and 20050101T00:00:00+12:00
,
respectively, and normalize to 20050101T12:00:00Z
and
20041231T12:00:00Z
.
The expression op:gYearequal(xs:gYear("197605:00"),
xs:gYear("1976"))
returns true()
.
Returns true if the two xs:gMonthDay
values have the same starting
instant, when considered as days in the same year.
Defines the
semantics of the "eq" operator on xs:gMonthDay
values. Also used in the
definition of the "ne" operator.
This function is
The starting instants of $arg1
and $arg2
are calculated by
supplying the missing components of $arg1
and $arg2
from the
xs:dateTime
template 1972xxxxT00:00:00
or an equivalent.
The function returns the result of comparing these two starting instants using
op:dateTimeequal
.
Assume that the dynamic context provides an implicit timezone value of
05:00
. Assume for the purposes of illustration that the
xs:dateTime
template used is 1972xxxxT00:00:00
(this
does not affect the result).
The expression op:gMonthDayequal(xs:gMonthDay("122514:00"),
xs:gMonthDay("1226+10:00"))
returns true()
. 19721225T00:00:0014:00
and
19721226T00:00:00+10:00
, respectively, and normalize to
19721225T14:00:00Z
and 19721225T14:00:00Z
.
).
The expression op:gMonthDayequal(xs:gMonthDay("1225"),
xs:gMonthDay("1226Z"))
returns false()
.
Returns true if the two xs:gMonth
values have the same starting
instant, when considered as months in the same year.
Defines the
semantics of the "eq" operator on xs:gMonth
values. Also used in the
definition of the "ne" operator.
This function is
The starting instants of $arg1
and $arg2
are calculated by
supplying the missing components of $arg1
and $arg2
from the
xs:dateTime
template 1972xx01T00:00:00
or an equivalent.
The function returns the result of comparing these two starting instants using
op:dateTimeequal
.
Assume that the dynamic context provides an implicit timezone value of
05:00
. Assume, also, that the xs:dateTime
template
chosen is 1972xx01T00:00:00
.
The expression op:gMonthequal(xs:gMonth("1214:00"),
xs:gMonth("12+10:00"))
returns false()
. 19721201T00:00:0014:00
and
19721201T00:00:00+10:00
, respectively, and normalize to
19721130T14:00:00Z
and 19721201T14:00:00Z
.
).
The expression op:gMonthequal(xs:gMonth("12"),
xs:gMonth("12Z"))
returns false()
.
Returns true if the two xs:gDay
values have the same starting
instant, when considered as days in the same month of the same year.
Defines the semantics
of the "eq" operator on xs:gDay
values. Also used in the definition of the
"ne" operator.
This function is
The starting instants of $arg1
and $arg2
are calculated by
supplying the missing components of $arg1
and $arg2
from the
xs:dateTime
template 197212xxT00:00:00
or an equivalent.
The function returns the result of comparing these two starting instants using
op:dateTimeequal
.
Assume that the dynamic context provides an implicit timezone value of
05:00
. Assume, also, that the xs:dateTime
template is
197212xxT00:00:00
.
The expression op:gDayequal(xs:gDay("2514:00"),
xs:gDay("25+10:00"))
returns false()
. 19721225T00:00:0014:00
and
19721225T00:00:00+10:00
, respectively, and normalize to
19721225T14:00:00Z
and 19721224T14:00:00Z
.
).
The expression op:gDayequal(xs:gDay("12"), xs:gDay("12Z"))
returns false()
.
The date and time datatypes may be considered to be composite datatypes in that they contain distinct properties or components. The extraction functions specified below extract a single component from a date or time value. In all cases the local value (that is, the original value as written, without any timezone adjustment) is used.
A time written as 24:00:00
is treated as 00:00:00
on the
following day.
Function  Meaning 

fn:yearfromdateTime  Returns the year component of an xs:dateTime . 
fn:monthfromdateTime  Returns the month component of an xs:dateTime . 
fn:dayfromdateTime  Returns the day component of an xs:dateTime . 
fn:hoursfromdateTime  Returns the hours component of an xs:dateTime . 
fn:minutesfromdateTime  Returns the minute component of an xs:dateTime . 
fn:secondsfromdateTime  Returns the seconds component of an xs:dateTime . 
fn:timezonefromdateTime  Returns the timezone component of an xs:dateTime . 
fn:yearfromdate  Returns the year component of an xs:date . 
fn:monthfromdate  Returns the month component of an xs:date . 
fn:dayfromdate  Returns the day component of an xs:date . 
fn:timezonefromdate  Returns the timezone component of an xs:date . 
fn:hoursfromtime  Returns the hours component of an xs:time . 
fn:minutesfromtime  Returns the minutes component of an xs:time . 
fn:secondsfromtime  Returns the seconds component of an xs:time . 
fn:timezonefromtime  Returns the timezone component of an xs:time . 
Returns the year component of an xs:dateTime
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
representing the year
component in the local value of $arg
. The result may be negative.
The expression fn:yearfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 1999
.
The expression fn:yearfromdateTime(xs:dateTime("19990531T21:30:0005:00"))
returns 1999
.
The expression fn:yearfromdateTime(xs:dateTime("19991231T19:20:00"))
returns 1999
.
The expression fn:yearfromdateTime(xs:dateTime("19991231T24:00:00"))
returns 2000
.
Returns the month component of an xs:dateTime
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
between 1 and 12, both
inclusive, representing the month component in the local value of $arg
.
The expression fn:monthfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 5
.
The expression fn:monthfromdateTime(xs:dateTime("19991231T19:20:0005:00"))
returns 12
.
The expression fn:monthfromdateTime(fn:adjustdateTimetotimezone(xs:dateTime("19991231T19:20:0005:00"),
xs:dayTimeDuration("PT0S")))
returns 1
.
Returns the day component of an xs:dateTime
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
between 1 and 31, both
inclusive, representing the day component in the local value of $arg
.
The expression fn:dayfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 31
.
The expression fn:dayfromdateTime(xs:dateTime("19991231T20:00:0005:00"))
returns 31
.
The expression fn:dayfromdateTime(fn:adjustdateTimetotimezone(xs:dateTime("19991231T19:20:0005:00"),
xs:dayTimeDuration("PT0S")))
returns 1
.
Returns the hours component of an xs:dateTime
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
between 0 and 23, both
inclusive, representing the hours component in the local value of $arg
.
The expression fn:hoursfromdateTime(xs:dateTime("19990531T08:20:0005:00"))
returns 8
.
The expression fn:hoursfromdateTime(xs:dateTime("19991231T21:20:0005:00"))
returns 21
.
The expression fn:hoursfromdateTime(fn:adjustdateTimetotimezone(xs:dateTime("19991231T21:20:0005:00"),
xs:dayTimeDuration("PT0S")))
returns 2
.
The expression fn:hoursfromdateTime(xs:dateTime("19991231T12:00:00"))
returns 12
.
The expression fn:hoursfromdateTime(xs:dateTime("19991231T24:00:00"))
returns 0
.
Returns the minute component of an xs:dateTime
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
value between 0 and 59, both
inclusive, representing the minute component in the local value of
$arg
.
The expression fn:minutesfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 20
.
The expression fn:minutesfromdateTime(xs:dateTime("19990531T13:30:00+05:30"))
returns 30
.
Returns the seconds component of an xs:dateTime
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:decimal
value greater than or equal
to zero and less than 60, representing the seconds and fractional seconds in the local
value of $arg
.
The expression fn:secondsfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 0
.
Returns the timezone component of an xs:dateTime
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns the timezone component of $arg
, if any. If
$arg
has a timezone component, then the result is an
xs:dayTimeDuration
that indicates deviation from UTC; its value may
range from +14:00 to 14:00 hours, both inclusive. If $arg
has no timezone
component, the result is the empty sequence.
The expression fn:timezonefromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns xs:dayTimeDuration("PT5H")
.
The expression fn:timezonefromdateTime(xs:dateTime("20000612T13:20:00Z"))
returns xs:dayTimeDuration("PT0S")
.
The expression fn:timezonefromdateTime(xs:dateTime("20040827T00:00:00"))
returns ()
.
Returns the year component of an xs:date
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
representing the year in the
local value of $arg
. The value may be negative.
The expression fn:yearfromdate(xs:date("19990531"))
returns 1999
.
The expression fn:yearfromdate(xs:date("20000101+05:00"))
returns 2000
.
Returns the month component of an xs:date
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
between 1 and 12, both
inclusive, representing the month component in the local value of $arg
.
The expression fn:monthfromdate(xs:date("1999053105:00"))
returns 5
.
The expression fn:monthfromdate(xs:date("20000101+05:00"))
returns 1
.
Returns the day component of an xs:date
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
between 1 and 31, both
inclusive, representing the day component in the localized value of
$arg
.
The expression fn:dayfromdate(xs:date("1999053105:00"))
returns 31
.
The expression fn:dayfromdate(xs:date("20000101+05:00"))
returns 1
.
Returns the timezone component of an xs:date
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns the timezone component of $arg
, if any. If
$arg
has a timezone component, then the result is an
xs:dayTimeDuration
that indicates deviation from UTC; its value may
range from +14:00 to 14:00 hours, both inclusive. If $arg
has no timezone
component, the result is the empty sequence.
The expression fn:timezonefromdate(xs:date("1999053105:00"))
returns xs:dayTimeDuration("PT5H")
.
The expression fn:timezonefromdate(xs:date("20000612Z"))
returns xs:dayTimeDuration("PT0S")
.
Returns the hours component of an xs:time
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
between 0 and 23, both
inclusive, representing the value of the hours component in the local value of
$arg
.
Assume that the dynamic context provides an implicit timezone value of
05:00
.
The expression fn:hoursfromtime(xs:time("11:23:00"))
returns 11
.
The expression fn:hoursfromtime(xs:time("21:23:00"))
returns 21
.
The expression fn:hoursfromtime(xs:time("01:23:00+05:00"))
returns 1
.
The expression fn:hoursfromtime(fn:adjusttimetotimezone(xs:time("01:23:00+05:00"),
xs:dayTimeDuration("PT0S")))
returns 20
.
The expression fn:hoursfromtime(xs:time("24:00:00"))
returns 0
.
Returns the minutes component of an xs:time
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:integer
value between 0 and 59, both
inclusive, representing the value of the minutes component in the local value of
$arg
.
The expression fn:minutesfromtime(xs:time("13:00:00Z"))
returns 0
.
Returns the seconds component of an xs:time
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns an xs:decimal
value greater than or equal
to zero and less than 60, representing the seconds and fractional seconds in the local
value of $arg
.
The expression fn:secondsfromtime(xs:time("13:20:10.5"))
returns 10.5
.
Returns the timezone component of an xs:time
.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
Otherwise, the function returns the timezone component of $arg
, if any. If
$arg
has a timezone component, then the result is an
xs:dayTimeDuration
that indicates deviation from UTC; its value may
range from +14:00 to 14:00 hours, both inclusive. If $arg
has no timezone
component, the result is the empty sequence.
The expression fn:timezonefromtime(xs:time("13:20:0005:00"))
returns xs:dayTimeDuration("PT5H")
.
The expression fn:timezonefromtime(xs:time("13:20:00"))
returns ()
.
Function  Meaning 

fn:adjustdateTimetotimezone  Adjusts an xs:dateTime value to a specific timezone, or to no
timezone at all. 
fn:adjustdatetotimezone  Adjusts an xs:date value to a specific timezone, or to no timezone
at all; the result is the date in the target timezone that contains the starting instant
of the supplied date. 
fn:adjusttimetotimezone  Adjusts an xs:time value to a specific timezone, or to no timezone
at all. 
These functions adjust the timezone component of an xs:dateTime
, xs:date
or
xs:time
value. The $timezone
argument to these functions is defined as an
xs:dayTimeDuration
but must be a valid timezone value.
Adjusts an xs:dateTime
value to a specific timezone, or to no
timezone at all.
The oneargument form of this function is
The twoargument form of this function is
If $timezone
is not specified, then the effective value of
$timezone
is the value of the implicit timezone in the dynamic
context.
If $arg
is the empty sequence, then the function returns the empty
sequence.
If $arg
does not have a timezone component and $timezone
is
the empty sequence, then the result is $arg
.
If $arg
does not have a timezone component and $timezone
is
not the empty sequence, then the result is $arg
with $timezone
as the timezone component.
If $arg
has a timezone component and $timezone
is the empty
sequence, then the result is the local value of $arg
without its timezone
component.
If $arg
has a timezone component and $timezone
is not the
empty sequence, then the result is the xs:dateTime
value that is equal to
$arg
and that has a timezone component equal to
$timezone
.
A $timezone
is less
than PT14H
or greater than PT14H
or is not an integral number
of minutes.
Assume the dynamic context provides an implicit timezone of 05:00
(PT5H0M)
.
let $tz10
:= xs:dayTimeDuration("PT10H")
The expression fn:adjustdateTimetotimezone(xs:dateTime('20020307T10:00:00'))
returns xs:dateTime('20020307T10:00:0005:00')
.
The expression fn:adjustdateTimetotimezone(xs:dateTime('20020307T10:00:0007:00'))
returns xs:dateTime('20020307T12:00:0005:00')
.
The expression fn:adjustdateTimetotimezone(xs:dateTime('20020307T10:00:00'),
$tz10)
returns xs:dateTime('20020307T10:00:0010:00')
.
The expression fn:adjustdateTimetotimezone(xs:dateTime('20020307T10:00:0007:00'),
$tz10)
returns xs:dateTime('20020307T07:00:0010:00')
.
The expression fn:adjustdateTimetotimezone(xs:dateTime('20020307T10:00:0007:00'),
xs:dayTimeDuration("PT10H"))
returns xs:dateTime('20020308T03:00:00+10:00')
.
The expression fn:adjustdateTimetotimezone(xs:dateTime('20020307T00:00:00+01:00'),
xs:dayTimeDuration("PT8H"))
returns xs:dateTime('20020306T15:00:0008:00')
.
The expression fn:adjustdateTimetotimezone(xs:dateTime('20020307T10:00:00'),
())
returns xs:dateTime('20020307T10:00:00')
.
The expression fn:adjustdateTimetotimezone(xs:dateTime('20020307T10:00:0007:00'),
())
returns xs:dateTime('20020307T10:00:00')
.
Adjusts an xs:date
value to a specific timezone, or to no timezone
at all; the result is the date in the target timezone that contains the starting instant
of the supplied date.
The oneargument form of this function is
The twoargument form of this function is
If $timezone
is not specified, then the effective value of
$timezone
is the value of the implicit timezone in the dynamic
context.
If $arg
is the empty sequence, then the function returns the empty
sequence.
If $arg
does not have a timezone component and $timezone
is
the empty sequence, then the result is the value of $arg
.
If $arg
does not have a timezone component and $timezone
is
not the empty sequence, then the result is $arg
with $timezone
as the timezone component.
If $arg
has a timezone component and $timezone
is the empty
sequence, then the result is the local value of $arg
without its timezone
component.
If $arg
has a timezone component and $timezone
is not the
empty sequence, then the function returns the value of the expression:
Let $dt
be the value of fn:dateTime($arg,
xs:time('00:00:00'))
.
Let $adt
be the value of fn:adjustdateTimetotimezone($dt,
$timezone)
The function returns the value of xs:date($adt)
A $timezone
is less
than PT14H
or greater than PT14H
or is not an integral number
of minutes.
Assume the dynamic context provides an implicit timezone of 05:00
(PT5H0M)
.
let $tz10
:= xs:dayTimeDuration("PT10H")
The expression fn:adjustdatetotimezone(xs:date("20020307"))
returns xs:date("2002030705:00")
.
The expression fn:adjustdatetotimezone(xs:date("2002030707:00"))
returns xs:date("2002030705:00")
. $arg
is converted to
xs:dateTime("20020307T00:00:0007:00")
. This is adjusted to the
implicit timezone, giving "20020307T02:00:0005:00"
.
).
The expression fn:adjustdatetotimezone(xs:date("20020307"),
$tz10)
returns xs:date("2002030710:00")
.
The expression fn:adjustdatetotimezone(xs:date("2002030707:00"),
$tz10)
returns xs:date("2002030610:00")
. $arg
is converted to the xs:dateTime
"20020307T00:00:0007:00"
. This is adjusted to the given timezone,
giving "20020306T21:00:0010:00"
. ).
The expression fn:adjustdatetotimezone(xs:date("20020307"),
())
returns xs:date("20020307")
.
The expression fn:adjustdatetotimezone(xs:date("2002030707:00"),
())
returns xs:date("20020307")
.
Adjusts an xs:time
value to a specific timezone, or to no timezone
at all.
The oneargument form of this function is
The twoargument form of this function is
If $timezone
is not specified, then the effective value of
$timezone
is the value of the implicit timezone in the dynamic
context.
If $arg
is the empty sequence, then the function returns the empty
sequence.
If $arg
does not have a timezone component and $timezone
is
the empty sequence, then the result is $arg
.
If $arg
does not have a timezone component and $timezone
is
not the empty sequence, then the result is $arg
with $timezone
as the timezone component.
If $arg
has a timezone component and $timezone
is the empty
sequence, then the result is the localized value of $arg
without its
timezone component.
If $arg
has a timezone component and $timezone
is not the
empty sequence, then:
Let $dt
be the xs:dateTime
value
fn:dateTime(xs:date('19721231'), $arg)
.
Let $adt
be the value of fn:adjustdateTimetotimezone($dt,
$timezone)
The function returns the xs:time
value
xs:time($adt)
.
A $timezone
is less
than PT14H
or greater than PT14H
or if does not contain an
integral number of minutes.
Assume the dynamic context provides an implicit timezone of 05:00
(PT5H0M)
.
let $tz10
:= xs:dayTimeDuration("PT10H")
The expression fn:adjusttimetotimezone(xs:time("10:00:00"))
returns xs:time("10:00:0005:00")
.
The expression fn:adjusttimetotimezone(xs:time("10:00:0007:00"))
returns xs:time("12:00:0005:00")
.
The expression fn:adjusttimetotimezone(xs:time("10:00:00"),
$tz10)
returns xs:time("10:00:0010:00")
.
The expression fn:adjusttimetotimezone(xs:time("10:00:0007:00"),
$tz10)
returns xs:time("07:00:0010:00")
.
The expression fn:adjusttimetotimezone(xs:time("10:00:00"), ())
returns xs:time("10:00:00")
.
The expression fn:adjusttimetotimezone(xs:time("10:00:0007:00"),
())
returns xs:time("10:00:00")
.
The expression fn:adjusttimetotimezone(xs:time("10:00:0007:00"),
xs:dayTimeDuration("PT10H"))
returns xs:time("03:00:00+10:00")
.
These functions support adding or subtracting a duration value to or from an
xs:dateTime
, an xs:date
or an xs:time
value. Appendix E of
Function  Meaning 

op:subtractdateTimes  Returns an xs:dayTimeDuration representing the amount of elapsed
time between the instants arg2 and arg1 . 
op:subtractdates  Returns the xs:dayTimeDuration that corresponds to the elapsed
time between the starting instant of $arg2 and the starting instant of
$arg2 . 
op:subtracttimes  Returns the xs:dayTimeDuration that corresponds to the elapsed
time between the values of $arg2 and $arg1 treated as times on
the same date. 
op:addyearMonthDurationtodateTime  Returns the xs:dateTime that is a given duration after a specified
xs:dateTime (or before, if the duration is negative). 
op:adddayTimeDurationtodateTime  Returns the xs:dateTime that is a given duration after a specified
xs:dateTime (or before, if the duration is negative). 
op:subtractyearMonthDurationfromdateTime  Returns the xs:dateTime that is a given duration before a
specified xs:dateTime (or after, if the duration is negative). 
op:subtractdayTimeDurationfromdateTime  Returns the xs:dateTime that is a given duration before a
specified xs:dateTime (or after, if the duration is negative). 
op:addyearMonthDurationtodate  Returns the xs:date that is a given duration after a specified
xs:date (or before, if the duration is negative). 
op:adddayTimeDurationtodate  Returns the xs:date that is a given duration after a specified
xs:date (or before, if the duration is negative). 
op:subtractyearMonthDurationfromdate  Returns the xs:date that is a given duration before a specified
xs:date (or after, if the duration is negative). 
op:subtractdayTimeDurationfromdate  Returns the xs:date that is a given duration before a specified
xs:date (or after, if the duration is negative). 
op:adddayTimeDurationtotime  Returns the xs:time value that is a given duration after a
specified xs:time (or before, if the duration is negative or causes
wraparound past midnight) 
op:subtractdayTimeDurationfromtime  Returns the xs:time value that is a given duration before a
specified xs:time (or after, if the duration is negative or causes
wraparound past midnight) 
A processor that limits the number of digits in date and time datatype
representations may encounter overflow and underflow conditions when it
tries to execute the functions in this section. In
these situations, the processor
The value spaces of the two totally ordered subtypes of
xs:duration
described in xs:integer
months for xs:yearMonthDuration
and xs:decimal
seconds for xs:dayTimeDuration
. If
a processor limits the number of digits allowed in the representation of
xs:integer
and xs:decimal
then overflow and
underflow situations can arise when it tries to execute the functions in
Returns an xs:dayTimeDuration
representing the amount of elapsed
time between the instants arg2
and arg1
.
Defines the semantics of the ""
operator on xs:dateTime
values.
This function is
If either $arg1
or $arg2
do not contain an explicit timezone
then, for the purpose of the operation, the implicit timezone provided by the dynamic
context (See
The function returns the elapsed time between the date/time instant arg2
and the date/time instant arg1
, computed according to the algorithm given
in Appendix E of xs:dayTimeDuration
.
If the normalized value of $arg1
precedes in time the normalized value of
$arg2
, then the returned value is a negative duration.
Assume that the dynamic context provides an implicit timezone value of
05:00
.
The expression op:subtractdateTimes(xs:dateTime("20001030T06:12:00"),
xs:dateTime("19991128T09:00:00Z"))
returns xs:dayTimeDuration("P337DT2H12M")
.
Returns the xs:dayTimeDuration
that corresponds to the elapsed
time between the starting instant of $arg2
and the starting instant of
$arg2
.
Defines the semantics of the "" operator on
xs:date
values.
This function is
If either $arg1
or $arg2
do not contain an explicit timezone
then, for the purpose of the operation, the implicit timezone provided by the dynamic
context (See
The starting instant of an xs:date
is the xs:dateTime
at
00:00:00
on that date.
The function returns the result of subtracting the two starting instants using
op:subtractdateTimes
.
If the starting instant of $arg1
precedes in time the starting instant of
$arg2
, then the returned value is a negative duration.
Assume that the dynamic context provides an implicit timezone value of
Z
.
The expression op:subtractdates(xs:date("20001030"),
xs:date("19991128"))
returns xs:dayTimeDuration("P337D")
. {2000,
10, 30, 0, 0, 0, PT0S}
and {1999, 11, 28, 0, 0, 0,
PT0S}
.).
Now assume that the dynamic context provides an implicit timezone value of
+05:00
.
The expression op:subtractdates(xs:date("20001030"),
xs:date("19991128Z"))
returns xs:dayTimeDuration("P336DT19H")
. {2000,
10, 29, 19, 0, 0, PT0S}
and {1999, 11, 28, 0, 0, 0,
PT0S}
.).
The expression op:subtractdates(xs:date("2000101505:00"),
xs:date("20001010+02:00"))
returns xs:dayTimeDuration("P5DT7H")
.
Returns the xs:dayTimeDuration
that corresponds to the elapsed
time between the values of $arg2
and $arg1
treated as times on
the same date.
Defines the semantics of the "" operator on
xs:time
values.
This function is
The function returns the result of the expression:
Any other reference date would work equally well.
Assume that the dynamic context provides an implicit timezone value of
05:00
. Assume, also, that the date components of the reference
xs:dateTime
correspond to "19721231"
.
The expression op:subtracttimes(xs:time("11:12:00Z"),
xs:time("04:00:00"))
returns xs:dayTimeDuration("PT2H12M")
. xs:dateTime
value {1972, 12, 31, 11, 12, 0, PT0S}
the xs:dateTime
value {1972, 12, 31, 9, 0, 0, PT0S}
.).
The expression op:subtracttimes(xs:time("11:00:0005:00"),
xs:time("21:30:00+05:30"))
returns xs:dayTimeDuration("PT0S")
. xs:dateTime
values are {1972, 12, 31, 11,
0, 0, PT5H}
and {1972, 12, 31, 21, 30, 0, PT5H30M}
. These
normalize to {1972, 12, 31, 16, 0, 0, PT0S}
and {1972, 12, 31,
16, 0, 0, PT0S}
. ).
The expression op:subtracttimes(xs:time("17:00:0006:00"),
xs:time("08:00:00+09:00"))
returns xs:dayTimeDuration("P1D")
. xs:dateTime
values are {1972,
12, 31, 23, 0, 0, PT0S}
and {1972, 12, 30, 23, 0, 0,
PT0S}
.).
The expression op:subtracttimes(xs:time("24:00:00"),
xs:time("23:59:59"))
returns xs:dayTimeDuration("PT23H59M59S")
. xs:dateTime
values are {1972,
12, 31, 0, 0, 0, ()}
and {1972, 12, 31, 23, 59, 59.0,
()}
.).
Returns the xs:dateTime
that is a given duration after a specified
xs:dateTime
(or before, if the duration is negative).
Defines the
semantics of the "+" operator on xs:dateTime
and
xs:yearMonthDuration
values.
This function is
The function returns the result of adding $arg2
to the value of
$arg1
using the algorithm described in Appendix E of $arg2
is negative, then the result xs:dateTime
precedes $arg1
.
The result has the same timezone as $arg1
. If $arg1
has no
timezone, the result has no timezone.
The expression op:addyearMonthDurationtodateTime(xs:dateTime("20001030T11:12:00"),
xs:yearMonthDuration("P1Y2M"))
returns xs:dateTime("20011230T11:12:00")
.
Returns the xs:dateTime
that is a given duration after a specified
xs:dateTime
(or before, if the duration is negative).
Defines the semantics
of the "+" operator on xs:dateTime
and xs:dayTimeDuration
values.
This function is
The function returns the result of adding $arg2
to the value of
$arg1
using the algorithm described in Appendix E of $arg2
is negative, then the result xs:dateTime
precedes $arg1
.
The result has the same timezone as $arg1
. If $arg1
has no
timezone, the result has no timezone.
The expression op:adddayTimeDurationtodateTime(xs:dateTime("20001030T11:12:00"),
xs:dayTimeDuration("P3DT1H15M"))
returns xs:dateTime("20001102T12:27:00")
.
Returns the xs:dateTime
that is a given duration before a
specified xs:dateTime
(or after, if the duration is negative).
Defines the
semantics of the "" operator on xs:dateTime
and
xs:yearMonthDuration
values.
This function is
The function returns the xs:dateTime
computed by negating
$arg2
and adding the result to the value of $arg1
using the
function op:addyearMonthDurationtodateTime
.
The expression op:subtractyearMonthDurationfromdateTime(xs:dateTime("20001030T11:12:00"),
xs:yearMonthDuration("P1Y2M"))
returns xs:dateTime("19990830T11:12:00")
.
Returns the xs:dateTime
that is a given duration before a
specified xs:dateTime
(or after, if the duration is negative).
Defines the semantics
of the "" operator on xs:dateTime
and xs:dayTimeDuration
values.
The function returns the xs:dateTime
computed by negating
$arg2
and adding the result to the value of $arg1
using the
function op:adddayTimeDurationtodateTime
.
The expression op:subtractdayTimeDurationfromdateTime(xs:dateTime("20001030T11:12:00"),
xs:dayTimeDuration("P3DT1H15M"))
returns xs:dateTime("20001027T09:57:00")
.
Returns the xs:date
that is a given duration after a specified
xs:date
(or before, if the duration is negative).
Defines the semantics
of the "+" operator on xs:date
and xs:yearMonthDuration
values.
This function is
The function returns the result of casting $arg1
to an
xs:dateTime
, adding $arg2
using the function
op:addyearMonthDurationtodateTime
, and casting the result back to an
xs:date
.
The expression op:addyearMonthDurationtodate(xs:date("20001030"),
xs:yearMonthDuration("P1Y2M"))
returns xs:date("20011230")
.
Returns the xs:date
that is a given duration after a specified
xs:date
(or before, if the duration is negative).
Defines the semantics of
the "+" operator on xs:date
and xs:dayTimeDuration
values.
This function is
The function returns the result of casting $arg1
to an
xs:dateTime
, adding $arg2
using the function
op:adddayTimeDurationtodateTime
, and casting the result back to an
xs:date
.
The expression op:adddayTimeDurationtodate(xs:date("20041030Z"),
xs:dayTimeDuration("P2DT2H30M0S"))
returns xs:date("20041101Z")
. xs:dateTime
value {2004, 10, 30, 0, 0, 0, PT0S}
.
Adding the second argument to this gives the xs:dateTime
value
{2004, 11, 1, 2, 30, 0, PT0S}
. The time components are then
discarded. ).
Returns the xs:date
that is a given duration before a specified
xs:date
(or after, if the duration is negative).
Defines the semantics
of the "" operator on xs:date
and xs:yearMonthDuration
values.
This function is
Returns the xs:date
computed by negating $arg2
and adding the
result to $arg1
using the function
op:addyearMonthDurationtodate
.
The expression op:subtractyearMonthDurationfromdate(xs:date("20001030"),
xs:yearMonthDuration("P1Y2M"))
returns xs:date("19990830")
.
The expression op:subtractyearMonthDurationfromdate(xs:date("20000229Z"),
xs:yearMonthDuration("P1Y"))
returns xs:date("19990228Z")
.
The expression op:subtractyearMonthDurationfromdate(xs:date("2000103105:00"),
xs:yearMonthDuration("P1Y1M"))
returns xs:date("1999093005:00")
.
Returns the xs:date
that is a given duration before a specified
xs:date
(or after, if the duration is negative).
Defines the semantics of
the "" operator on xs:date
and xs:dayTimeDuration
values.
This function is
Returns the xs:date
computed by negating $arg2
and adding the
result to $arg1
using the function
op:adddayTimeDurationtodate
.
The expression op:subtractdayTimeDurationfromdate(xs:date("20001030"),
xs:dayTimeDuration("P3DT1H15M"))
returns xs:date("20001026")
.
Returns the xs:time
value that is a given duration after a
specified xs:time
(or before, if the duration is negative or causes
wraparound past midnight)
Defines the semantics of
the "+" operator on xs:time
and xs:dayTimeDuration
values.
First, the days component in the canonical lexical representation of $arg2
is set to zero (0) and the value of the resulting xs:dayTimeDuration
is
calculated. Alternatively, the value of $arg2
modulus 86,400 is used as the
second argument. This value is added to the value of $arg1
converted to an
xs:dateTime
using a reference date such as 19721231
, and
the time component of the result is returned. Note that the xs:time
returned may occur in a following or preceding day and may be less than
$arg1
.
The result has the same timezone as $arg1
. If $arg1
has no
timezone, the result has no timezone.
The expression op:adddayTimeDurationtotime(xs:time("11:12:00"),
xs:dayTimeDuration("P3DT1H15M"))
returns xs:time("12:27:00")
.
The expression op:adddayTimeDurationtotime(xs:time("23:12:00+03:00"),
xs:dayTimeDuration("P1DT3H15M"))
returns xs:time("02:27:00+03:00")
. {0, 0, 0, 2, 27, 0, PT3H}
).
Returns the xs:time
value that is a given duration before a
specified xs:time
(or after, if the duration is negative or causes
wraparound past midnight)
Defines the semantics of
the "" operator on xs:time
and xs:dayTimeDuration
values.
This function is
The function returns the result of negating $arg2
and adding the result to
$arg1
using the function adddayTimeDurationtotime
.
The expression op:subtractdayTimeDurationfromtime(xs:time("11:12:00"),
xs:dayTimeDuration("P3DT1H15M"))
returns xs:time("09:57:00")
.
The expression op:subtractdayTimeDurationfromtime(xs:time("08:20:0005:00"),
xs:dayTimeDuration("P23DT10H10M"))
returns xs:time("22:10:0005:00")
.
Function  Meaning 

fn:formatdateTime  Returns a string containing an xs:dateTime value formatted for display. 
fn:formatdate  Returns a string containing an xs:date value formatted for display. 
fn:formattime  Returns a string containing an xs:time value formatted for display. 
Three functions are provided to represent dates and times as a string, using the conventions of a selected calendar, language, and country. The signatures are presented first, followed by the rules which apply to each of the functions.
Returns a string containing an xs:dateTime
value formatted for display.
The twoargument form of this function is
The fiveargument form of this function is
See
Returns a string containing an xs:date
value formatted for display.
The twoargument form of this function is
The fiveargument form of this function is
See
Returns a string containing an xs:time
value formatted for display.
The twoargument form of this function is
The fiveargument form of this function is
See
The fn:formatdateTime
, fn:formatdate
,
and fn:formattime
functions format $value
as a string using
the picture string specified by the $picture
argument,
the calendar specified by the $calendar
argument,
the language specified by the $language
argument,
and the country $place
argument.
The result of the function is the formatted string representation of the supplied
xs:dateTime
, xs:date
, or xs:time
value.
fn:formatdateTime
, fn:formatdate
,
and fn:formattime
are referred to collectively as the
If $value
is the empty sequence, the function returns the empty sequence.
Calling the twoargument form of each of the three functions is equivalent to calling the fiveargument form with each of the last three arguments set to an empty sequence.
For details of the $language
, $calendar
, and
$place
arguments, see
In general, the use of an invalid $picture
,
$language
, $calendar
, or
$place
argument results in a dynamic error. By contrast,
use of an option in any of these arguments that is valid but not supported by the implementation is
not an error, and in these cases the implementation is required to output the value in a fallback
representation.
The picture consists of a sequence of variable markers and literal substrings.
A substring enclosed in square brackets is interpreted as a variable marker; substrings
not enclosed in square brackets are taken as literal substrings.
The literal substrings are optional and if present are rendered unchanged, including any whitespace.
If an opening or closing square bracket
is required within a literal substring, it
A variable marker consists of a component specifier followed optionally by one or two presentation modifiers and/or optionally by a width modifier. Whitespace within a variable marker is ignored.
The variable marker may be separated into its components by applying the following rules:
The component specifier is always present and is always a single letter.
The width modifier may be recognized by the presence of a comma.
The substring between the component specifier and the comma (if present) or the end of the string (if there is no comma) contains the first and second presentation modifiers, both of which are optional. If this substring contains a single character, this is interpreted as the first presentation modifier. If it contains more than one character, the last character is examined: if it is valid as a second presentation modifier then it is treated as such, and the preceding part of the substring constitutes the first presentation modifier. Otherwise, the second presentation modifier is presumed absent and the whole substring is interpreted as the first presentation modifier.
The
Specifier  Meaning  Default Presentation Modifier 

Y  year (absolute value)  1 
M  month in year  1 
D  day in month  1 
d  day in year  1 
F  day of week  n 
W  week in year  1 
w  week in month  1 
H  hour in day (24 hours)  1 
h  hour in halfday (12 hours)  1 
P  am/pm marker  n 
m  minute in hour  01 
s  second in minute  01 
f  fractional seconds  1 
Z  timezone  01:01 
z  timezone (same as Z, but modified where appropriate to include a prefix
as a time offset using GMT, for example GMT+1 or GMT05:00. For this component there is a fixed
prefix of GMT , or a localized
variation thereof for the chosen language, and the remainder of the value is formatted as for specifier Z .
 01:01 
C  calendar: the name or abbreviation of a calendar name  n 
E  era: the name of a baseline for the numbering of years, for example the reign of a monarch  n 
A
A $value
,
for example if the picture supplied to the fn:formattime
refers
to the year, month, or day component.
It is not an error to include a timezone component when the supplied value has no timezone. In these circumstances the timezone component will be ignored.
The first
any format token permitted as a primary format token in the second argument
of the fn:formatinteger
function, indicating
that the value of the component is to be output numerically using the specified number format (for example,
1
, 01
, i
, I
, w
, W
,
or Ww
) or
the format token n
, N
,
or Nn
, indicating that the value of the component is to be output by name,
in lowercase, uppercase, or titlecase respectively. Components that can be output by name
include (but are not limited to) months, days of the week, timezones, and eras.
If the processor cannot output these components by name for the chosen calendar and language
then it must use an
If a comma is to be used as a grouping separator within the format token, then there must be a width
specifier. More specifically: if a variable marker
contains one or more commas, then the last comma is treated as introducing the width modifier, and all others
are treated as grouping separators. So [Y9,999,*]
will output the year as 2,008
.
If the implementation does not support the use of the requested format token, it
If the first presentation modifier is present, then it may optionally be followed by a second presentation modifier as follows:
Modifier  Meaning 

either a or t  indicates alphabetic or traditional numbering respectively,
the default being fn:formatinteger . 
either c or o  indicates cardinal or ordinal numbering respective, for example
7 or seven for a cardinal number, or 7th ,
seventh , or 7º
for an ordinal number.
This has the same meaning as
in the second argument of fn:formatinteger .
The actual representation of the ordinal form of a number
may depend not only on the language, but also on the grammatical context (for example,
in some languages it must agree in gender). 
Although the formatting rules are expressed in terms of the rules
for format tokens in fn:formatinteger
, the formats actually used may be specialized
to the numbering of date components where appropriate. For example, in Italian, it is conventional to
use an ordinal number (primo
) for the first day of the month, and cardinal numbers
(due, tre, quattro ...
) for the remaining days. A processor may therefore use
this convention to number days of the month, ignoring the presence or absence of the ordinal
presentation modifier.
Whether or not a presentation modifier is included, a width modifier may be supplied. This indicates the number of characters or digits to be included in the representation of the value.
The width modifier, if present, is introduced by a comma or semicolon. It takes the form:
"," minwidth ("" maxwidth)?
where minwidth
is either an unsigned integer indicating the minimum number of characters to
be output, or *
indicating that there is no explicit minimum, and
maxwidth
is either an unsigned integer indicating the maximum number of characters to
be output, or *
indicating that there is no explicit maximum; if maxwidth
is omitted then *
is assumed. Both integers, if present,
A format token containing more than one digit, such as 001
or 9999
, sets the
minimum and maximum width to the number of digits appearing in the format token; if a width
modifier is also present, then the width modifier takes precedence.
A numeric format token may contain optionaldigitsigns
and groupingseparators as described for fn:formatinteger
. However, the
grouping separator cannot be a closing square bracket ("]"
).
A format token consisting of a single digit,
such as 1
, does not constrain the number of digits in the output.
In the case of fractional seconds in particular, [f001]
requests three decimal digits,
[f01]
requests two digits, but [f1]
will produce an
[f1,11]
.
If the minimum and maximum width are unspecified, then the output uses as
many characters as are required to
represent the value of the component without truncation and without padding: this is referred to below
as the z
), the full representation consists of a sign for the offset, the
number of hours of the offset, and if the offset is not an integral number of hours,
a colon (:
) followed by the two digits of the minutes of the offset..
If the full representation of the value exceeds the specified maximum width, then the processor
N
, n
, or Nn
,
this is done by abbreviating the name,
using either conventional abbreviations if available, or crude righttruncation if not. For example,
setting maxwidth
to 4
indicates that fourletter abbreviations
maxwidth
requests omission of highorder
digits from the year, for example, if maxwidth
is set to 2
then the year 2003
will be output as 03
. In the case of the fractional seconds
component, the value is rounded to the specified size as if by applying the function
roundhalftoeven(fractionalseconds, maxwidth)
.
If no mechanism is available for fitting the value within the specified
maximum width (for example, when roman numerals are used), then the value
If the full representation of the value is shorter than the specified minimum width, then the processor
For decimal representations of
numbers, this
For timezone offsets this should be done by first appending
a colon (:
) followed by two
zero digits from the appropriate set of digit characters if the full
representation does not already include a minutes component and if
the specified minimum width permits adding three characters,
and then if necessary prepending zero digits from the
appropriate set of digit characters to the hour component.
In other cases,
it
Special rules apply to the formatting of timezones. When the component specifiers Z
or z
are used, the rules in this section override any rules given elsewhere in the case of
discrepancies.
If the date/time value to be formatted does not include a timezone offset, then the timezone component specifier is generally ignored (results in no output). The exception is where military timezones are used (format ZZ) in which case the string "J" is output, indicating local time.
When the component specifier is z
, the output is the same as for component specifier
Z
, except that it is prefixed by the characters GMT
or some localized
equivalent. The prefix is omitted, however, in cases where the timezone is identified by name rather than by
a numeric offset from UTC.
If the first presentation modifier is numeric and comprises one or two digits
with no groupingseparator (for example 1
or 01
), then the timezone is formatted as a displacement from UTC in hours, preceded by a plus or minus
sign: for example 5
or +03
. If the actual timezone offset is not an integral number of hours,
then the minutes part of the offset is appended, separated by a colon: for example +10:30
or
1:15
.
If the first presentation modifier is numeric with a groupingseparator (for example 1:01
or 01.01
), then the timezone offset is output in hours and minutes, separated by the grouping separator,
even if the number of minutes is zero: for example +5:00
or +10.30
.
If the first presentation modifier is numeric and comprises three or four digits with no
groupingseparator, for example 001
or 0001
, then the timezone offset
is shown in hours and minutes with no separator, for example 0500
or +1030
.
If the first presentation modifier is numeric, in any of the above formats, and the second
presentation modifier is t
, then a zero timezone offset (that is, UTC) is output as Z
instead
of a signed numeric value. In this presentation modifier is absent or if the timezone offset is nonzero,
then the displayed timezone offset is preceded by a "" sign for negative offsets
or a "+" sign for nonnegative offsets.
If the first presentation modifier is Z
, then the timezone is formatted
as a military timezone letter, using the convention Z = +00:00, A = +01:00, B = +02:00, ..., M = +12:00,
N = 01:00, O = 02:00, ... Y = 12:00. The letter J (meaning local time) is used in the case of a
value that does not specify a timezone offset. Timezone offsets that have no representation in this system
(for example Indian Standard Time, +05:30) are output as if the format 01:01
had been requested.
If the first presentation modifier is N
, then the timezone is output
(where possible) as a timezone name, for example EST
or CET
. The same timezone
offset has different names in different places; it is therefore $place
argument.
In the absence of this information, the implementation may apply a default, for example by using the timezone
names that are conventional in North America. If no timezone name can be identified, the timezone offset is
output using the fallback format +01:01
.
The following examples illustrate options for timezone formatting.
Variable marker  $place  Timezone offsets (with time = 12:00:00)  

10:00  05:00  +00:00  +05:30  +13:00  
[Z]  ()  10:00  05:00  +00:00  +05:30  +13:00 
[Z0]  ()  10  5  +0  +5:30  +13 
[Z0:00]  ()  10:00  5:00  +0:00  +5:30  +13:00 
[Z00:00]  ()  10:00  05:00  +00:00  +05:30  +13:00 
[Z0000]  ()  1000  0500  +0000  +0530  +1300 
[Z00:00t]  ()  10:00  05:00  Z  +05:30  +13:00 
[z]  ()  GMT10:00  GMT05:00  GMT+00:00  GMT+05:30  GMT+13:00 
[ZZ]  ()  W  R  Z  +05:30  +13:00 
[ZN]  "us"  HST  EST  GMT  IST  +13:00 
[H00]:[M00] [ZN]  "America/New_York"  06:00 EST  12:00 EST  07:00 EST  01:30 EST  18:00 EST 
The set of languages, calendars, and
If the fallback representation uses a different calendar from that requested,
the output string [Calendar: X]
(where X is the calendar actually used),
localized as appropriate to the
requested language. If the fallback representation uses a different language
from that requested, the output string [Language: Y]
(where Y is the language
actually used) localized in an
implementationdependent way. If a particular component of the value cannot be output in
the requested format, it
The $language
argument specifies the language to be used for the result string
of the function. The value of the argument xml:lang
attribute (see [XML]).
Note that this permits the identification of sublanguages
based on country codes (from
If the $language
argument is omitted or is set to an empty sequence, or if it is set to an invalid value or a
value that the implementation does not recognize,
then the processor uses
The language is used to select the appropriate languagedependent forms of:
twenty, 20th, twentieth
)Where appropriate this choice may also take into account the value of the
$place
argument, though this language
argument.
The choice of the names and abbreviations used in any given language is
Jul
while another uses Jly
. In German,
one implementation might represent Saturday as Samstag
while another
uses Sonnabend
. Implementations
Where ordinal numbers are used, the selection of the correct representation of the
ordinal (for example, the linguistic gender)
The calendar
attribute specifies that the dateTime
, date
,
or time
supplied in the $value
argument
A calendar value
If the $calendar
argument is omitted or is set to an empty sequence
then the default calendar defined in the dynamic context is used.
The calendars listed below were known to be in use during the last hundred years. Many other calendars have been used in the past.
This specification does not define any of these calendars, nor the way that they
map to the value space of the xs:date
data type in $place
and/or $language
arguments, with the
$place
argument taking precedence.
Information about some of these calendars, and algorithms for converting between them, may
be found in
Designator  Calendar 

AD  Anno Domini (Christian Era) 
AH  Anno Hegirae (Muhammedan Era) 
AME  Mauludi Era (solar years since Mohammed's birth) 
AM  Anno Mundi (Jewish Calendar) 
AP  Anno Persici 
AS  Aji Saka Era (Java) 
BE  Buddhist Era 
CB  Cooch Behar Era 
CE  Common Era 
CL  Chinese Lunar Era 
CS  Chula Sakarat Era 
EE  Ethiopian Era 
FE  Fasli Era 
ISO  ISO 8601 calendar 
JE  Japanese Calendar 
KE  Khalsa Era (Sikh calendar) 
KY  Kali Yuga 
ME  Malabar Era 
MS  Monarchic Solar Era 
NS  Nepal Samwat Era 
OS  Old Style (Julian Calendar) 
RS  Rattanakosin (Bangkok) Era 
SE  Saka Era 
SH  Mohammedan Solar Era (Iran) 
SS  Saka Samvat 
TE  Tripurabda Era 
VE  Vikrama Era 
VS  Vikrama Samvat Era 
At least one of the above calendars
The ISO 8601 calendar (ISO
,
is very similar to the Gregorian calendar designated AD
, but it
differs in several ways. The ISO calendar
is intended to ensure that date and time formats can be read
easily by other software, as well as being legible for human
users. The ISO calendar
prescribes the use of particular numbering conventions as defined in
ISO 8601, rather than allowing these to be localized on a perlanguage basis.
In particular it
provides a numeric 'week date' format which identifies dates by
year, week of the year, and day in the week;
in the ISO calendar the days of the week are numbered from 1 (Monday) to 7 (Sunday), and
week 1 in any calendar year is the week (from Monday to Sunday) that includes the first Thursday
of that year. The numeric values of the components year, month, day, hour, minute, and second
are the same in the ISO calendar as the values used in the lexical representation of the date and
time as defined in
The value space of the date and time data types, as defined in XML Schema, is based on
absolute points in time. The lexical space of these data types defines a
representation of these absolute points in time using the proleptic Gregorian calendar,
that is, the modern Western calendar extrapolated into the past and the future; but the value space
is calendarneutral. The
15020111
(the day on which Pope Gregory XIII was born) might be
formatted using the Old Style (Julian) calendar as 1 January 1502
. This reflects the fact
that there was at that time a tenday difference between the two calendars. It would be
incorrect, and would produce incorrect results, to represent this date in an element or attribute
of type xs:date
as 15020101
, even though this might reflect the way
the date was recorded in contemporary documents.
When referring to years occurring in antiquity, modern historians generally
use a numbering system in which there is no year zero (the year before 1 CE
is thus 1 BCE). This is the convention that xs:date
and xs:dateTime
does not include a year zero: however, a future edition is
expected to endorse the ISO 8601 convention. This means that the date on
which Julius Caesar was assassinated has the ISO 8601 lexical representation
00430313, but will be formatted as 15 March 44 BCE in the Julian calendar
or 13 March 44 BCE in the Gregorian calendar (dependant on the chosen
localization of the names of months and eras).
The intended use of the $place
argument is to identify
the place where an event
represented by the dateTime
, date
,
or time
supplied in the $value
argument took place or will take place.
$place
argument is omitted or is set
to an empty sequence, then the default place defined in the dynamic context is used.
Country codes are defined in
Olson timezone names are defined in the publicdomain
This argument is not intended to identify the location of the user
for whom the date or time is being formatted;
that should be done by means of the $language
attribute.
This information
The geographical area identified by a country code is defined by the boundaries as they existed at the time of the date to be formatted, or the presentday boundaries for dates in the future.
If the $place
argument is supplied in the form
of an Olson timezone name that is recognized by the implementation, then the date or
time being formatted is adjusted to the timezone offset applicable in that timezone.
For example, if the xs:dateTime
value 20100215T12:00:00Z
is formatted with the $place
argument set to
America/New_York
, then the output will be as if the value
20100215T07:00:0005:00
had been supplied. This adjustment takes daylight
savings time into account where possible; if the date in question falls during
daylight savings time in New York, then it is adjusted to timezone offset PT4H
rather than PT5H
. Adjustment using daylight savings time is only possible
where the value includes a date, and where the date is within the range covered
by the timezone database.
The following examples show a selection of dates and times and the way they might be formatted. These examples assume the use of the Gregorian calendar as the default calendar.
Required Output  Expression 

20021231

formatdate($d, "[Y0001][M01][D01]")

12312002

formatdate($d, "[M][D][Y]")

31122002

formatdate($d, "[D][M][Y]")

31 XII 2002

formatdate($d, "[D1] [MI] [Y]")

31st December, 2002

formatdate($d, "[D1o] [MNn], [Y]", "en", (), ())

31 DEC 2002

formatdate($d, "[D01] [MN,*3] [Y0001]", "en", (), ())

December 31, 2002

formatdate($d, "[MNn] [D], [Y]", "en", (), ())

31 Dezember, 2002

formatdate($d, "[D] [MNn], [Y]", "de", (), ())

Tisdag 31 December 2002

formatdate($d, "[FNn] [D] [MNn] [Y]", "sv", (), ())

[20021231]

formatdate($d, "[[[Y0001][M01][D01]]]")

Two Thousand and Three

formatdate($d, "[YWw]", "en", (), ())

einunddreißigste Dezember

formatdate($d, "[Dwo] [MNn]", "de", (), ())

3:58 PM

formattime($t, "[h]:[m01] [PN]", "en", (), ())

3:58:45 pm

formattime($t, "[h]:[m01]:[s01] [Pn]", "en", (), ())

3:58:45 PM PDT

formattime($t, "[h]:[m01]:[s01] [PN] [ZN,*3]", "en", (), ())

3:58:45 o'clock PM PDT

formattime($t, "[h]:[m01]:[s01] o'clock [PN] [ZN,*3]", "en", (), ())

15:58

formattime($t,"[H01]:[m01]")

15:58:45.762

formattime($t,"[H01]:[m01]:[s01].[f001]")

15:58:45 GMT+02:00

formattime($t,"[H01]:[m01]:[s01] [z,66]", "en", (), ())

15.58 Uhr GMT+2

formattime($t,"[H01]:[m01] Uhr [z]", "de", (), ())

3.58pm on Tuesday, 31st December

formatdateTime($dt, "[h].[m01][Pn] on [FNn], [D1o] [MNn]")

12/31/2002 at 15:58:45

formatdateTime($dt, "[M01]/[D01]/[Y0001] at [H01]:[m01]:[s01]")

The following examples use calendars other than the Gregorian calendar.
These examples use nonLatin characters which might not display correctly in all browsers, depending on the system configuration.
Description  Request  Result 

Islamic 
formatdate($d, "[D١] [Mn] [Y١]", "ar", "AH", ())
 ٢٦ ﺸﻭّﺍﻝ ١٤٢٣ 
Jewish (with Western numbering) 
formatdate($d, "[D] [Mn] [Y]", "he", "AM", ())
 26 טבת 5763 
Jewish (with traditional numbering) 
formatdate($d, "[Dאt] [Mn] [Yאt]", "he", "AM", ())
 כ״ו טבת תשס״ג 
Julian (Old Style) 
formatdate($d, "[D] [MNn] [Y]", "en", "OS", ())
 18 December 2002 
Thai 
formatdate($d, "[D๑] [Mn] [Y๑]", "th", "BE", ())
 ๓๑ ธันวาคม ๒๕๔๕ 
In addition to the xs:QName
constructor function, QName values can
be constructed by combining a namespace URI, prefix, and local name, or by resolving
a lexical QName against the inscope namespaces of an element node. This section
defines these functions.
Leading and trailing whitespace, if present, is stripped from
string arguments before the result is constructed.
Function  Meaning 

fn:resolveQName  Returns an xs:QName value (that is, an expandedQName) by taking
an xs:string that has the lexical form of an xs:QName (a
string in the form "prefix:localname" or "localname") and resolving it using the
inscope namespaces for a given element. 
fn:QName  Constructs an xs:QName value given a namespace URI and a lexical
QName. 
Returns an xs:QName
value (that is, an expandedQName) by taking
an xs:string
that has the lexical form of an xs:QName
(a
string in the form "prefix:localname" or "localname") and resolving it using the
inscope namespaces for a given element.
This function is
If $qname
is the empty sequence, returns the empty sequence.
More specifically, the function searches the namespace bindings of $element
for a binding whose name matches the prefix of $qname
, or the zerolength
string if it has no prefix, and constructs an expandedQName whose local name is taken
from the supplied $qname
, and whose namespace URI is taken from the string
value of the namespace binding.
If the $qname
has no prefix, and there is no namespace binding for
$element
corresponding to the default (unnamed) namespace, then the
resulting expandedQName has no namespace part.
The prefix (or absence of a prefix) in the supplied $qname
argument is
retained in the returned expandedQName, as discussed in
A $qname
does not
have the correct lexical form for an instance of xs:QName
.
A $qname
has a
prefix and there is no namespace binding for $element
that matches this
prefix.
Sometimes the requirement is to construct an xs:QName
without using the
default namespace. This can be achieved by writing:
If the requirement is to construct an xs:QName
using the namespaces in the
static context, then the xs:QName
constructor should be used.
Assume that the element bound to $element
has a single namespace binding
bound to the prefix eg
.
fn:resolveQName("hello", $element)
returns a QName with local name
"hello" that is in no namespace.
fn:resolveQName("eg:myFunc", $element)
returns an xs:QName
whose namespace URI is specified by the namespace binding corresponding to the prefix
"eg" and whose local name is "myFunc".
Constructs an xs:QName
value given a namespace URI and a lexical
QName.
This function is
The namespace URI in the returned QName is taken from $paramURI
. If
$paramURI
is the zerolength string or the empty sequence, it represents
"no namespace".
The prefix (or absence of a prefix) in $paramQName
is retained in the
returned xs:QName
value.
The local name in the result is taken from the local part of
$paramQName
.
A $paramQName
does
not have the correct lexical form for an instance of xs:QName
.
A $paramURI
is the
zerolength string or the empty sequence, and the value of $paramQName
contains a colon (:
).
A $paramURI
is not a valid URI (XML Namespaces 1.0) or
IRI (XML Namespaces 1.1).
Note that unlike the xs:QName
constructor, this function
does not require a string literal as the argument.
fn:QName("http://www.example.com/example", "person")
returns an
xs:QName
with namespace URI = "http://www.example.com/example", local
name = "person" and prefix = "".
fn:QName("http://www.example.com/example", "ht:person")
returns an
xs:QName
with namespace URI = "http://www.example.com/example", local
name = "person" and prefix = "ht".
This section specifies functions on QNames as defined in
Function  Meaning 

op:QNameequal  Returns true if two supplied QNames have the same namespace URI
and the same local part. 
fn:prefixfromQName  Returns the prefix component of the supplied QName. 
fn:localnamefromQName  Returns the local part of the supplied QName. 
fn:namespaceurifromQName  Returns the namespace URI part of the supplied QName. 
fn:namespaceuriforprefix  Returns the namespace URI of one of the inscope namespaces for
$element , identified by its namespace prefix. 
fn:inscopeprefixes  Returns the prefixes of the inscope namespaces for an element node. 
Returns true
if two supplied QNames have the same namespace URI
and the same local part.
Defines the semantics
of the "eq" and "ne" operators on values of type xs:QName
.
This function is
The function returns true
if the namespace URIs of $arg1
and
$arg2
are equal and the local names of $arg1
and
$arg2
are equal.
Otherwise, the function returns false
.
The namespace URI parts are considered equal if they are both fn:codepointequal
function.
The local parts are also compared under the rules of the fn:codepointequal
function.
The prefix parts of $arg1
and $arg2
, if any, are ignored.
Returns the prefix component of the supplied QName.
This function is
If $arg
is the empty sequence the function returns the empty sequence.
If $arg
has no prefix component the function returns the empty
sequence.
Otherwise, the function returns an xs:NCName
representing the prefix
component of $arg
.
Returns the local part of the supplied QName.
This function is
If $arg
is the empty sequence the function returns the empty sequence.
Otherwise, the function returns an xs:NCName
representing the local part of
$arg
.
The expression fn:localnamefromQName(fn:QName("http://www.example.com/example",
"person"))
returns "person"
.
Returns the namespace URI part of the supplied QName.
This function is
If $arg
is the empty sequence the function returns the empty sequence.
Otherwise, the function returns an xs:anyURI
representing the namespace URI
part of $arg
.
If $arg
is in no namespace, the function returns the zerolength
xs:anyURI
.
The expression fn:namespaceurifromQName(fn:QName("http://www.example.com/example",
"person"))
returns xs:anyURI("http://www.example.com/example")
.
Returns the namespace URI of one of the inscope namespaces for
$element
, identified by its namespace prefix.
This function is
If $element
has an inscope namespace whose namespace prefix is equal to
$prefix
, the function returns the namespace URI of that namespace.
If $element
has no inscope namespace whose namespace prefix is equal to
$prefix
, the function returns the empty sequence.
If $prefix
is the zerolength string or the empty
sequence, then if $element
has a default namespace (that is, a namespace
node with no name), the function returns the namespace URI of the default namespace. If
$element
has no default namespace, the function returns the empty
sequence.
Prefixes are equal only if their Unicode codepoints match exactly.
let $e
:=
The expression fn:namespaceuriforprefix("z", $e)
returns "http://example.org/two"
.
The expression fn:namespaceuriforprefix("", $e)
returns "http://example.org/one"
.
The expression fn:namespaceuriforprefix((), $e)
returns "http://example.org/one"
.
The expression fn:namespaceuriforprefix("xml", $e)
returns "http://www.w3.org/XML/1998/namespace"
.
The expression fn:namespaceuriforprefix("xml", $e)
returns "http://www.w3.org/XML/1998/namespace"
.
Returns the prefixes of the inscope namespaces for an element node.
This function is
The function returns a sequence of strings representing the prefixes of the inscope
namespaces for $element
.
For namespace bindings that have a prefix, the function returns the prefix as an
xs:NCName
. For the default namespace, which has no prefix, it returns
the zerolength string.
The result sequence contains no duplicates.
The ordering of the result sequence is
The following comparison operators on xs:base64Binary
and
xs:hexBinary
values are defined. Comparisons take two operands of
the same type; that is, both operands must be xs:base64Binary
or
both operands may be xs:hexBinary
. Each returns a boolean value.
A value of type xs:hexBinary
can be compared with a value of type
xs:base64Binary
by casting one value to the other type. See
Function  Meaning 

op:hexBinaryequal  Returns true if two xs:hexBinary values contain the same octet
sequence. 
op:base64Binaryequal  Returns true if two xs:base64Binary values contain the same octet
sequence. 
Returns true if two xs:hexBinary
values contain the same octet
sequence.
Defines the
semantics of the "eq" and "ne" operators on xs:hexBinary
values.
The function returns true
if $value1
and $value2
are of the same length, measured in binary octets, and contain the same octets in the
same order. Otherwise, it returns false
.
Returns true if two xs:base64Binary
values contain the same octet
sequence.
Defines the
semantics of the "eq" and "ne" operators on xs:base64Binary
values.
The function returns true
if $value1
and $value2
are of the same length, measured in binary octets, and contain the same octets in the
same order. Otherwise, it returns false
.
This section specifies operators that take xs:NOTATION
values as arguments.
Function  Meaning 

op:NOTATIONequal  Returns true if the two xs:NOTATION values have the
same namespace URI and the same local part. 
Returns true
if the two xs:NOTATION
values have the
same namespace URI and the same local part.
Defines the
semantics of the "eq" and "ne" operators on values of type xs:NOTATION
.
The function returns true
if the namespace URIs of $arg1
and
$arg2
are equal and the local names of $arg1
and
$arg2
are equal.
Otherwise, the function returns false
.
The namespace URI parts are considered equal if they are both fn:codepointequal
function.
The local parts are also compared under the rules of the fn:codepointequal
function.
The prefix parts of $arg1
and $arg2
, if any, are ignored.
This section specifies functions and operators on nodes. Nodes are formally defined
in
Function  Meaning 

fn:name  Returns the name of a node, as an xs:string that is either the
zerolength string, or has the lexical form of an xs:QName . 
fn:localname  Returns the local part of the name of $arg as an
xs:string that is either the zerolength string, or has the lexical form
of an xs:NCName . 
fn:namespaceuri  Returns the namespace URI part of the name of
$arg , as an xs:anyURI value. 
fn:lang  This function tests whether the language of $node , or the context
item if the second argument is omitted, as specified by xml:lang attributes
is the same as, or is a sublanguage of, the language specified by
$testlang . 
op:issamenode  Returns true if the two arguments refer to the same node. 
op:nodebefore  Returns true if the node identified by the first argument precedes the node identified by the second argument in document order. 
op:nodeafter  Returns true if the node identified by the first argument follows the node identified by the second argument in document order. 
fn:root  Returns the root of the tree to which $arg belongs. This will
usually, but not necessarily, be a document node. 
fn:path  Returns a path expression that can be used to select the supplied node relative to the root of its containing document. 
fn:haschildren  Returns true if the supplied node has one or more child nodes (of any kind). 
fn:innermost  Returns every node within the input sequence that is not an ancestor of another member of the input sequence; the nodes are returned in document order with duplicates eliminated. 
fn:outermost  Returns every node within the input sequence that has no ancestor that is itself a member of the input sequence; the nodes are returned in document order with duplicates eliminated. 
For the illustrative examples below assume an XQuery or transformation operating on a
PurchaseOrder document containing a number of lineitem elements. Each lineitem has
child elements called description, price, quantity, etc. whose content is different
for each lineitem. Quantity has simple content of type xs:decimal
.
Further assume that variables $item1
, $item2
, etc. are
each bound to single lineitem element nodes in the document in sequence and that
the value of the quantity child of the first lineitem is 5.0
.
let $po
:=
let $item1
:= $po/lineitem[1]
let $item2
:= $po/lineitem[2]
let $item3
:= $po/lineitem[3]
Returns the name of a node, as an xs:string
that is either the
zerolength string, or has the lexical form of an xs:QName
.
The zeroargument form of this function is
The oneargument form of this function is
If the argument is omitted, it defaults to the context item (.
). The
behavior of the function if the argument is omitted is exactly the same as if the
context item had been passed as the argument.
If the argument is supplied and is the empty sequence, the function returns the zerolength string.
If the node identified by $arg
has no name (that is, if it is a document
node, a comment, a text node, or a namespace node having no name), the function returns
the zerolength string.
Otherwise, the function returns the value of the expression
fn:string(fn:nodename($arg))
.
The following errors may be raised when $arg
is omitted: if the context
item is
Returns the local part of the name of $arg
as an
xs:string
that is either the zerolength string, or has the lexical form
of an xs:NCName
.
The zeroargument form of this function is
The oneargument form of this function is
If the argument is omitted, it defaults to the context item (.
). The
behavior of the function if the argument is omitted is exactly the same as if the
context item had been passed as the argument.
If the argument is supplied and is the empty sequence, the function returns the zerolength string.
If the node identified by $arg
has no name (that is, if it is a document
node, a comment, a text node, or a namespace node having no name), the function returns
the zerolength string.
Otherwise, the function returns the local part of the expandedQName of the node
identified by $arg
, as determined by the dm:nodename
accessor
defined in xs:string
whose lexical form is an xs:NCName
.
The following errors may be raised when $arg
is omitted: if the context
item is absent
Returns the namespace URI part of the name of
$arg
, as an xs:anyURI
value.
The zeroargument form of this function is
The oneargument form of this function is
If the argument is omitted, it defaults to the context node (.
). The
behavior of the function if the argument is omitted is exactly the same as if the
context item had been passed as the argument.
If the node identified by $arg
is neither an element nor an attribute node,
or if it is an element or attribute node whose expandedQName (as determined by the
dm:nodename
accessor in the xs:anyURI
value.
Otherwise, the result will be the namespace URI part of the expandedQName of the node
identified by $arg
, as determined by the dm:nodename
accessor
defined in xs:anyURI
value.
The following errors may be raised when $arg
is omitted: if the context
item is absent
This function tests whether the language of $node
, or the context
item if the second argument is omitted, as specified by xml:lang
attributes
is the same as, or is a sublanguage of, the language specified by
$testlang
.
The oneargument form of this function is
The twoargument form of this function is
The behavior of the function if the second argument is omitted is exactly the same as if
the context item (.
) had been passed as the second argument.
The language of the argument $node
, or the context item if the second
argument is omitted, is determined by the value of the xml:lang
attribute
on the node, or, if the node has no such attribute, by the value of the
xml:lang
attribute on the nearest ancestor of the node that has an
xml:lang
attribute. If there is no such ancestor, then the function
returns false
.
If $testlang
is the empty sequence it is interpreted as the zerolength
string.
The relevant xml:lang
attribute is determined by the value of the XPath
expression:
If this expression returns an empty sequence, the function returns false
.
Otherwise, the function returns true
if and only if, based on a caseless
default match as specified in section 3.13 of
$testlang
is equal to the stringvalue of the relevant
xml:lang
attribute, or
$testlang
is equal to some substring of the stringvalue of the
relevant xml:lang
attribute that starts at the start of the
stringvalue and ends immediately before a hyphen, "" (the character "" is
HYPHENMINUS, #x002D).
When $arg
is omitted the following errors may be raised: if the context
item is absent
The expression fn:lang("en")
would return true
if the
context node were any of the following four elements:
<para xml:lang="en"/>
<div xml:lang="en"><para>And now, and
forever!</para></div>
<para xml:lang="EN"/>
<para xml:lang="enus"/>
The expression fn:lang("fr")
would return false
if the
context node were <para xml:lang="EN"/>
Returns true if the two arguments refer to the same node.
Defines the semantics of the "is" operator on nodes.
If the node identified by the value of $arg1
is the same node as the node
identified by the value of $arg2
(that is, the two nodes have the same
identity), then the function returns true
; otherwise, the function returns
false
.
The expression op:issamenode($item1, $item1)
returns true()
.
The expression op:issamenode($item1, $item2)
returns false()
.
Returns true if the node identified by the first argument precedes the node identified by the second argument in document order.
Defines the semantics of the "<<" operator.
If the node identified by the value of $arg1
occurs in document order
before the node identified by the value of $arg2
, then the function returns
true
; otherwise, it returns false
.
The rules determining the order of nodes within a single document and in different
documents can be found in
The expression op:nodebefore($item1, $item2)
returns true()
.
The expression op:nodebefore($item1, $item1)
returns false()
.
Returns true if the node identified by the first argument follows the node identified by the second argument in document order.
Defines the semantics of the ">>" operator.
If the node identified by the value of $arg1
occurs in document order after
the node identified by the value of $arg2
, the function returns
true
; otherwise, it returns false
.
The rules determining the order of nodes within a single document and in different
documents can be found in
The expression op:nodeafter($item1, $item2)
returns false()
.
The expression op:nodeafter($item1, $item1)
returns false()
.
The expression op:nodeafter($item2, $item1)
returns true()
.
Returns the root of the tree to which $arg
belongs. This will
usually, but not necessarily, be a document node.
The zeroargument form of this function is
The oneargument form of this function is
If the function is called without an argument, the context item (.
) is used
as the default argument. The behavior of the function if the argument is omitted is
exactly the same as if the context item had been passed as the argument.
The function returns the value of the expression
($arg/ancestororself::node())[1]
.
When $arg
is omitted the following errors may be raised : if the context
item is absent
These examples use some variables which could be defined in
Or they could be defined in
fn:root($i)
returns the element node $i
fn:root($o/quantity)
returns the element node $o
fn:root($odoc//quantity)
returns the document node $odoc
fn:root($newi)
returns the element node $o
The final three examples could be made typesafe by wrapping their operands with
fn:exactlyone()
.
Returns a path expression that can be used to select the supplied node relative to the root of its containing document.
The oneargument form of this function is
The twoargument form of this function is
The behavior of the function if the argument is omitted is exactly the same as if
the context item (.
) had been passed as the argument.
If $arg
is the empty sequence, the function returns the empty sequence.
If $arg
is a document node, the function returns the string "/"
.
Otherwise, the function constructs a string that consists of a sequence of
steps, one for each ancestororself of $arg
other than the "Q{http://www.w3.org/2005/xpathfunctions}root()"
if the root node
is not a document node."/"
followed by a string whose form depends
on the kind of node selected by that step, as follows:
For an element node, Q{
, where
is the
namespace URI of the node name or the empty string if the node is in no
namespace,
is the local part of the node name, and
is an
integer representing the position of the selected node among its likenamed
siblings.
For an attribute node:
if the node is in no namespace, @
,
where
is the local part
of the node name
otherwise, @Q{
, where
is the namespace URI of the
node name, and
is the local part of the node name
For a text node: text()[
where
is an integer
representing the position of the selected node among its text node siblings
For a comment node: comment()[
where
is an integer
representing the position of the selected node among its comment node siblings
For a processinginstruction node:
processinginstruction(
where
is the name of the
processing instruction node and
is an integer representing the
position of the selected node among its likenamed processinginstruction node
siblings
For a namespace node:
If the namespace node has a name:
namespace::
, where
is the local part
of the name of the namespace node (which represents the namespace prefix).
If the namespace node has no name (that is, it represents
the default namespace):
namespace::*[Q{http://www.w3.org/2005/xpathfunctions}localname()=""]
let $e
:=
The expression fn:path($e)
returns '/'
.
The expression fn:path($e/*:p)
returns '/Q{http://example.com/one}p[1]'
.
The expression fn:path($e/*:p/@xml:lang)
returns '/Q{http://example.com/one}p[1]/@Q{http://www.w3.org/XML/1998/namespace}lang'
.
The expression fn:path($e/*:p/@author)
returns '/Q{http://example.com/one}p[1]/@author'
.
The expression fn:path($e/*:p/*:br[2])
returns '/Q{http://example.com/one}p[1]/Q{http://example.com/one}br[2]'
.
The expression fn:path($e//text()[startswith(normalizespace(), 'Tochter')])
returns '/Q{http://example.com/one}p[1]/text()[2]'
.
let $emp
:=
The expression fn:path($emp)
returns 'Q{http://www.w3.org/2005/xpathfunctions}root()'
.
The expression fn:path($emp/@xml:id)
returns 'Q{http://www.w3.org/2005/xpathfunctions}root()/@Q{http://www.w3.org/XML/1998/namespace}id'
.
The expression fn:path($emp/empnr)
returns 'Q{http://www.w3.org/2005/xpathfunctions}root()/Q{}empnr[1]'
.
Returns true if the supplied node has one or more child nodes (of any kind).
The zeroargument form of this function is
The oneargument form of this function is
If the argument is omitted, it defaults to the context item (.
). The
behavior of the function if the argument is omitted is exactly the same as if the
context item had been passed as the argument.
$node
matches the expected
type node()?
, fn:haschildren($node)
is defined to be
the same as the result of the expression
fn:exists($node/child::node())
.
The following errors may be raised when $node
is omitted: if the context
item is
If $node
is an empty sequence the result is false.
The motivation for this function is to support streamed evaluation. According to the
streaming rules in
This is because it makes two downward selections to read the child row
elements. The use of fn:haschildren
in the xsl:if
conditional
is intended to circumvent this restriction.
Although the function was introduced to support streaming use cases, it has general utility as a convenience function.
Returns every node within the input sequence that is not an ancestor of another member of the input sequence; the nodes are returned in document order with duplicates eliminated.
This function is
The effect of the function call fn:innermost($nodes)
is defined to be
equivalent to the result of the expression $nodes except
$nodes/ancestor::node()
.
That is, the function takes as input a sequence of nodes, and returns every node within the sequence that is not an ancestor of another node within the sequence; the nodes are returned in document order with duplicates eliminated.
If the source document contains nested sections represented by div
elements, the expression innermost(//div)
returns those div
elements that do not contain further div
elements.
Returns every node within the input sequence that has no ancestor that is itself a member of the input sequence; the nodes are returned in document order with duplicates eliminated.
This function is
The effect of the function call fn:outermost($nodes)
is defined to be
equivalent to the result of the expression $nodes[not(ancestor::node() intersect
$nodes)]/.
.
That is, the function takes as input a sequence of nodes, and returns every node within
the sequence that
The formulation $nodes except $nodes/descendant::node()
might appear to be
simpler, but does not correctly account for attribute nodes, as these are not
descendants of their parent element.
The motivation for the function was based on XSLT streaming use cases. There are cases
where the outermost(//section)
but do not allow //section
; the
function can therefore be useful in cases where it is known that sections will not be
nested, as well as cases where the application actually wishes to process all sections
except those that are nested within another.
If the source document contains nested sections represented by div
elements, the expression outermost(//div)
returns those div
elements that div
elements.
A sequence
is an ordered collection of zero or more items
.
An item
is either a node or an atomic value. The terms
sequence
and item
are defined formally in
The following functions are defined on sequences. These functions work on any sequence, without performing any operations that are sensitive to the individual items in the sequence.
Function  Meaning 

op:concatenate  Returns the concatenation of two sequences. 
fn:empty  Returns true if the argument is the empty sequence. 
fn:exists  Returns true if the argument is a nonempty sequence. 
fn:head  Returns the first item in a sequence. 
fn:tail  Returns all but the first item in a sequence. 
fn:insertbefore  Returns a sequence constructed by inserting an item or a sequence of items at a given position within an existing sequence. 
fn:remove  Returns a new sequence containing all the items of $target except
the item at position $position . 
fn:reverse  Reverses the order of items in a sequence. 
fn:subsequence  Returns the contiguous sequence of items in the value of
$sourceSeq beginning at the position indicated by the value of
$startingLoc and continuing for the number of items indicated by the
value of $length . 
fn:unordered  Returns the items of $sourceSeq in an 
As in the previous section, for the illustrative examples below, assume an XQuery
or transformation operating on a nonempty Purchase Order document containing a
number of lineitem elements. The variable $seq
is bound to the
sequence of lineitem nodes in document order. The variables
$item1
, $item2
, etc. are bound to separate, individual
lineitem nodes in the sequence.
Returns the concatenation of two sequences.
Defines the semantics of the infix operator ",".
This function is
The function returns a sequence consisting of all the items in $seq1
followed by all the items in $seq2
.
For detailed type semantics, see [Formal Semantics].
If either sequence is the empty sequence, the other operand is returned.
The expression op:concatenate((1, 2, 3), (4, 5))
returns (1, 2, 3, 4, 5)
.
The expression op:concatenate((1, 2, 3), ())
returns (1, 2, 3)
.
The expression op:concatenate((), ())
returns ()
.
Returns true if the argument is the empty sequence.
This function is
If the value of $arg
is the empty sequence, the function returns
true
; otherwise, the function returns false
.
The expression fn:empty((1,2,3)[10])
returns true()
.
The expression fn:empty(fn:remove(("hello", "world"), 1))
returns false()
.
Returns true if the argument is a nonempty sequence.
This function is
If the value of $arg
is a nonempty sequence, the function returns
true
; otherwise, the function returns false
.
The expression fn:exists(fn:remove(("hello"), 1))
returns false()
.
The expression fn:exists(fn:remove(("hello", "world"), 1))
returns true()
.
Returns the first item in a sequence.
This function is
The function returns the value of the expression $arg[1]
If $arg
is the empty sequence, the empty sequence is returned. Otherwise
the first item in the sequence is returned.
The expression fn:head(1 to 5)
returns 1
.
The expression fn:head(("a", "b", "c"))
returns "a"
.
The expression fn:head(())
returns ()
.
Returns all but the first item in a sequence.
This function is
The function returns the value of the expression subsequence($arg, 2)
If $arg
is the empty sequence, or a sequence containing a single item, then
the empty sequence is returned.
The expression fn:tail(1 to 5)
returns (2, 3, 4, 5)
.
The expression fn:tail(("a", "b", "c"))
returns ("b", "c")
.
The expression fn:tail("a")
returns ()
.
The expression fn:tail(())
returns ()
.
Returns a sequence constructed by inserting an item or a sequence of items at a given position within an existing sequence.
This function is
The value returned by the function consists of all items of $target
whose
index is less than $position
, followed by all items of
$inserts
, followed by the remaining elements of $target
, in
that order.
For detailed type semantics, see [Formal Semantics].
If $target
is the empty sequence, $inserts
is returned. If
$inserts
is the empty sequence, $target
is returned.
If $position
is less than one (1), the first position, the effective value
of $position
is one (1). If $position
is greater than the
number of items in $target
, then the effective value of
$position
is equal to the number of items in $target
plus
1.
The value of $target
is not affected by the sequence construction.
let $abc
:= ("a", "b", "c")
The expression fn:insertbefore($abc, 0, "z")
returns ("z", "a", "b", "c")
.
The expression fn:insertbefore($abc, 1, "z")
returns ("z", "a", "b", "c")
.
The expression fn:insertbefore($abc, 2, "z")
returns ("a", "z", "b", "c")
.
The expression fn:insertbefore($abc, 3, "z")
returns ("a", "b", "z", "c")
.
The expression fn:insertbefore($abc, 4, "z")
returns ("a", "b", "c", "z")
.
Returns a new sequence containing all the items of $target
except
the item at position $position
.
This function is
The function returns a sequence consisting of all items of $target
whose
index is less than $position
, followed by all items of $target
whose index is greater than $position
.
For detailed type semantics, see [Formal Semantics].
If $position
is less than 1 or greater than the number of items in
$target
, $target
is returned.
If $target
is the empty sequence, the empty sequence is returned.
let $abc
:= ("a", "b", "c")
The expression fn:remove($abc, 0)
returns ("a", "b", "c")
.
The expression fn:remove($abc, 1)
returns ("b", "c")
.
The expression fn:remove($abc, 6)
returns ("a", "b", "c")
.
The expression fn:remove((), 3)
returns ()
.
Reverses the order of items in a sequence.
This function is
The function returns a sequence containing the items in $arg
in reverse
order.
For detailed type semantics, see [Formal Semantics].
If $arg
is the empty sequence, the empty sequence is returned.
let $abc
:= ("a", "b", "c")
The expression fn:reverse($abc)
returns ("c", "b", "a")
.
The expression fn:reverse(("hello"))
returns ("hello")
.
The expression fn:reverse(())
returns ()
.
Returns the contiguous sequence of items in the value of
$sourceSeq
beginning at the position indicated by the value of
$startingLoc
and continuing for the number of items indicated by the
value of $length
.
This function is
In the twoargument case, returns:
In the threeargument case, returns:
For detailed type semantics, see [Formal Semantics].
The first item of a sequence is located at position 1, not position 0.
If $sourceSeq
is the empty sequence, the empty sequence is returned.
If $startingLoc
is zero or negative, the subsequence includes items from
the beginning of the $sourceSeq
.
If $length
is not specified, the subsequence includes items to the end of
$sourceSeq
.
If $length
is greater than the number of items in the value of
$sourceSeq
following $startingLoc
, the subsequence includes
items to the end of $sourceSeq
.
As an exception to the previous two notes, if
$startingLoc
is INF
and $length
is
+INF
, then fn:round($startingLoc) + fn:round($length)
is
NaN
; since position() lt NaN
is always false, the result is
an empty sequence.
The reason the function accepts arguments of type xs:double
is that many
computations on untyped data return an xs:double
result; and the reason for
the rounding rules is to compensate for any imprecision in these floatingpoint
computations.
let $seq
:= ("item1", "item2", "item3", "item4", "item5")
The expression fn:subsequence($seq, 4)
returns ("item4", "item5")
.
The expression fn:subsequence($seq, 3, 2)
returns ("item3", "item4")
.
Returns the items of $sourceSeq
in an
This function is
The function returns the items of $sourceSeq
in an
Query optimizers may be able to do a better job if the order of the output sequence is not specified. For example, when retrieving prices from a purchase order, if an index exists on prices, it may be more efficient to return the prices in index order rather than in document order.
The expression fn:unordered((1, 2, 3, 4, 5))
returns some permutation of (1, 2, 3, 4, 5)
.
The functions in this section rely on comparisons between the items in one or more sequences.
Function  Meaning 

fn:distinctvalues  Returns the values that appear in a sequence, with duplicates eliminated. 
fn:indexof  Returns a sequence of positive integers giving the positions within the
sequence $seq of items that are equal to $search . 
fn:deepequal  This function assesses whether two sequences are deepequal to each other. To be deepequal, they must contain items that are pairwise deepequal; and for two items to be deepequal, they must either be atomic values that compare equal, or nodes of the same kind, with the same name, whose children are deepequal. 
Returns the values that appear in a sequence, with duplicates eliminated.
The oneargument form of this function is
The twoargument form of this function is
The function returns the sequence that results from removing from $arg
all
but one of a set of values that are equal to one another. Values are compared using the
eq
operator, subject to the caveats defined below.
Values of type xs:untypedAtomic
are compared as if they were of type
xs:string
.
Values that cannot be compared, because the eq
operator is not defined for
their types, are considered to be distinct.
The collation used by this function is determined according to the rules in
For xs:float
and xs:double
values, positive zero is equal to
negative zero and, although NaN
does not equal itself, if $arg
contains multiple NaN
values a single NaN
is returned.
If xs:dateTime
, xs:date
or xs:time
values do not
have a timezone, they are considered to have the implicit timezone provided by the
dynamic context for the purpose of comparison. Note that xs:dateTime
,
xs:date
or xs:time
values can compare equal even if their
timezones are different.
The order in which the sequence of values is returned is
Which value of a set of values that compare equal is returned is
The static type of the result is a sequence of prime types as defined in [Formal Semantics].
If the input sequence contains values of different numeric types that differ from
each other by small amounts, then the eq operator is not transitive, because of
rounding effects occurring during type promotion. In the situation where the input
contains three values A
, B
, and C
such that
A eq B
, B eq C
, but A ne C
, then the number
of items in the result of the function (as well as the choice of which items are
returned) is
For example, this arises when computing:
because the values of type xs:float
and xs:double
both
compare equal to the value of type xs:decimal
but not equal to each
other.
If $arg
is the empty sequence, the function returns the empty sequence.
The expression fn:distinctvalues((1, 2.0, 3, 2))
returns some permutation of (1, 3, 2.0)
.
The expression fn:distinctvalues((xs:untypedAtomic("cherry"),
xs:untypedAtomic("plum"), xs:untypedAtomic("plum")))
returns some permutation of (xs:untypedAtomic("cherry"),
xs:untypedAtomic("plum"))
.
Returns a sequence of positive integers giving the positions within the
sequence $seq
of items that are equal to $search
.
The twoargument form of this function is
The threeargument form of this function is
The function returns a sequence of positive integers giving the positions within the
sequence $seq
of items that are equal to $search
.
The collation used by this function is determined according to the rules in
The items in the sequence $seq
are compared with $search
under
the rules for the eq
operator. Values of type xs:untypedAtomic
are compared as if they were of type xs:string
. Values that cannot be
compared, because the eq
operator is not defined for their types, are
considered to be distinct. If an item compares equal, then the position of that item in
the sequence $seq
is included in the result.
The first item in a sequence is at position 1, not position 0.
The result sequence is in ascending numeric order.
If the value of $seq
is the empty sequence, or if no item in
$seq
matches $search
, then the function returns the empty
sequence.
No error occurs if noncomparable values are encountered. So when
comparing two atomic values, the effective boolean value of fn:indexof($a,
$b)
is true if $a
and $b
are equal, false if they
are not equal or not comparable.
The expression fn:indexof((10, 20, 30, 40), 35)
returns ()
.
The expression fn:indexof((10, 20, 30, 30, 20, 10), 20)
returns (2, 5)
.
The expression fn:indexof(("a", "sport", "and", "a", "pastime"),
"a")
returns (1, 4)
.
The expression fn:indexof(currentdate(), 23)
returns ()
.
If @a
is an attribute of type
xs:NMTOKENS
whose string value is "red green blue"
, and
whose typed value is therefore ("red", "green", "blue")
, then
fn:indexof(@a, "blue")
returns 3
. This is because the
function calling mechanism atomizes the attribute node to produce a sequence of three
xs:NMTOKEN
values.
This function assesses whether two sequences are deepequal to each other. To be deepequal, they must contain items that are pairwise deepequal; and for two items to be deepequal, they must either be atomic values that compare equal, or nodes of the same kind, with the same name, whose children are deepequal.
The twoargument form of this function is
The threeargument form of this function is
The $collation
argument identifies a collation which is used at all levels
of recursion when strings are compared (but not when names are compared), according to
the rules in
If the two sequences are both empty, the function returns true
.
If the two sequences are of different lengths, the function returns
false
.
If the two sequences are of the same length, the function returns true
if
and only if every item in the sequence $parameter1
is deepequal to the
item at the same position in the sequence $parameter2
. The rules for
deciding whether two items are deepequal follow.
Call the two items $i1
and $i2
respectively.
If $i1
and $i2
are both atomic values, they are deepequal if
and only if ($i1 eq $i2)
is true
, or if both values are
NaN
. If the eq
operator is not defined for $i1
and $i2
, the function returns false
.
If one of the pair $i1
or $i2
is an atomic value and the
other is not,
the function returns false
.
If $i1
and $i2
are both nodes, they are compared as described
below:
If the two nodes are of different kinds, the result is false
.
If the two nodes are both document nodes then they are deepequal if and only if
the sequence $i1/(*text())
is deepequal to the sequence
$i2/(*text())
.
If the two nodes are both element nodes then they are deepequal if and only if all of the following conditions are satisfied:
The two nodes have the same name, that is (nodename($i1) eq
nodename($i2))
.
Either both nodes are both annotated as having simple content or both nodes are annotated as having complex content. For this purpose "simple content" means either a simple type or a complex type with simple content; "complex content" means a complex type whose variety is mixed, elementonly, or empty.
It is a consequence of this rule that validating a document D against a schema will usually (but not necessarily) result in a document that is not deepequal to D. The exception is when the schema allows all elements to have mixed content.
The two nodes have the same number of attributes, and for every attribute
$a1
in $i1/@*
there exists an attribute
$a2
in $i2/@*
such that $a1
and
$a2
are deepequal.
One of the following conditions holds:
Both element nodes are annotated as having simple content
$i1
is deepequal to the typed value
of $i2
.
Both element nodes have a type annotation that is $i1/*
is
deepequal to the sequence $i2/*
.
Both element nodes have a type annotation that is $i1/(*text())
is
deepequal to the sequence $i2/(*text())
.
Both element nodes have a type annotation that is
If the two nodes are both attribute nodes then they are deepequal if and only if both the following conditions are satisfied:
The two nodes have the same name, that is (nodename($i1) eq
nodename($i2))
.
The typed value of $i1
is deepequal to the typed value of
$i2
.
If the two nodes are both processing instruction nodes
The two nodes have the same name, that is (nodename($i1) eq
nodename($i2))
.
The string value of $i1
is equal to the string value of
$i2
.
If the two nodes are both namespace nodes, then they are deepequal if and only if both the following conditions are satisfied:
The two nodes either have the same name or are both nameless, that is
fn:deepequal(nodename($i1), nodename($i2))
.
The string value of $i1
is equal to the string value of
$i2
when compared using the Unicode codepoint collation.
If the two nodes are both text nodes or comment nodes, then they are deepequal if and only if their stringvalues are equal.
A
The two nodes are not required to have the same type annotation, and they are not
required to have the same inscope namespaces. They may also differ in their parent,
their base URI, and the values returned by the isid
and
isidrefs
accessors (see
The contents of comments and processing instructions are significant only if these nodes appear directly as items in the two sequences being compared. The content of a comment or processing instruction that appears as a descendant of an item in one of the sequences being compared does not affect the result. However, the presence of a comment or processing instruction, if it causes a text node to be split into two text nodes, may affect the result.
The result of fn:deepequal(1, currentdateTime())
is false
;
it does not raise an error.
let $at
:=
The expression fn:deepequal($at, $at/*)
returns false()
.
The expression fn:deepequal($at/name[1], $at/name[2])
returns false()
.
The expression fn:deepequal($at/name[1], $at/name[3])
returns true()
.
The expression fn:deepequal($at/name[1], 'Peter Parker')
returns false()
.
The following functions test the cardinality of their sequence arguments.
Function  Meaning 

fn:zeroorone  Returns $arg if it contains zero or one items. Otherwise, raises
an error. 
fn:oneormore  Returns $arg if it contains one or more items. Otherwise, raises
an error. 
fn:exactlyone  Returns $arg if it contains exactly one item. Otherwise, raises an
error. 
The functions fn:zeroorone
, fn:oneormore
, and
fn:exactlyone
defined in this section, check that the cardinality
of a sequence is in the expected range. They are particularly useful with regard
to static typing. For example, the function call fn:remove($seq, fn:indexof($seq2, 'abc'))
requires the result of the call on fn:indexof
to be a singleton integer,
but the static type system cannot infer this; writing the expression as
fn:remove($seq, fn:exactlyone(fn:indexof($seq2, 'abc')))
will provide a suitable static type at query analysis time, and ensures that the length of the sequence is
correct with a dynamic check at query execution time.
The type signatures for these functions deliberately declare the argument type as
item()*
, permitting a sequence of any length. A more restrictive
signature would defeat the purpose of the function, which is to defer
cardinality checking until query execution time.
Returns $arg
if it contains zero or one items. Otherwise, raises
an error.
This function is
Except in error cases, the function returns $arg
unchanged.
For detailed type semantics, see [Formal Semantics].
A $arg
contains more
than one item.
Returns $arg
if it contains one or more items. Otherwise, raises
an error.
This function is
Except in error cases, the function returns $arg
unchanged.
For detailed type semantics, see [Formal Semantics].
A $arg
is an empty
sequence.
Returns $arg
if it contains exactly one item. Otherwise, raises an
error.
This function is
Except in error cases, the function returns $arg
unchanged.
For detailed type semantics, see [Formal Semantics].
A $arg
is an empty
sequence or a sequence containing more than one item.
Function  Meaning 

op:union  Constructs a sequence containing every node that occurs in the values of either
$arg1 or $arg2 , eliminating duplicates and sorting the
result in document order. 
op:intersect  Constructs a sequence containing every node that occurs in the values of both
$arg1 and $arg2 , eliminating duplicates and sorting the
result in document order. 
op:except  Constructs a sequence containing every node that occurs in the value of
$arg1 but not in the value of $arg2 , eliminating duplicates
and sorting the result in document order. 
As in the previous sections, for the illustrative examples below, assume an
XQuery or transformation operating on a Purchase Order document containing a
number of lineitem elements. The variables $item1
,
$item2
, etc. are bound to individual lineitem nodes in the
sequence. We use sequences of these nodes in some of the examples below.
Constructs a sequence containing every node that occurs in the values of either
$arg1
or $arg2
, eliminating duplicates and sorting the
result in document order.
Defines the semantics of the "union" or "" operator.
The function returns a sequence containing every node that occurs in the values of
either $arg1
or $arg2
, eliminating duplicate nodes. Nodes are
returned in document order.
Two nodes $n1
and $n2
are duplicates if they satisfy
op:issamenode($n1, $n2)
.
For detailed type semantics, see [Formal Semantics].
If either operand is the empty sequence, the result is a sequence containing the nodes in the other operand in document order after eliminating duplicates.
let $seq1
:= ($item1, $item2)
let $seq2
:= ($item2, $item2, $item1)
let $seq3
:= ($item2, $item3)
The expression op:union($seq1, $seq1)
returns ($item1, $item2)
.
The expression op:union($seq2, $seq3)
returns ($item1, $item2, $item3)
.
The expression op:union($seq2, ())
returns ($item1, $item2)
.
Constructs a sequence containing every node that occurs in the values of both
$arg1
and $arg2
, eliminating duplicates and sorting the
result in document order.
Defines the semantics of the "intersect" operator.
The function returns a sequence containing every node that occurs in the values of both
$arg1
and $arg2
, eliminating duplicate nodes. Nodes are
returned in document order.
Two nodes $n1
and $n2
are duplicates if they satisfy
op:issamenode($n1, $n2)
.
For detailed type semantics, see [Formal Semantics].
If either operand is the empty sequence, the function returns the empty sequence.
let $seq1
:= ($item1, $item2)
let $seq2
:= ($item2, $item2, $item1)
let $seq3
:= ($item2, $item3)
The expression op:intersect($seq1, $seq1)
returns ($item1, $item2)
.
The expression op:intersect($seq2, $seq3)
returns ($item2)
.
The expression op:intersect($seq2, ())
returns ()
.
The expression op:intersect($item1, $item3)
returns ()
.
Constructs a sequence containing every node that occurs in the value of
$arg1
but not in the value of $arg2
, eliminating duplicates
and sorting the result in document order.
Defines the semantics of the "except" operator.
The function returns a sequence containing every node that occurs in the value of
$arg1
provided that it does not occur in the value of
$arg2
. Duplicate nodes are eliminated, and nodes are returned in document
order.
Two nodes $n1
and $n2
are duplicates if they satisfy
op:issamenode($n1, $n2)
.
For detailed type semantics, see [Formal Semantics].
If $arg1
is the empty sequence, the empty sequence is returned.
If $arg2
is the empty sequence, a sequence is returned containing the nodes
in $arg1
in document order after eliminating duplicates.
let $seq1
:= ($item1, $item2)
let $seq2
:= ($item2, $item2, $item1)
let $seq3
:= ($item2, $item3)
The expression op:except($seq1, $seq1)
returns ()
.
The expression op:except($seq2, $seq1)
returns ()
.
The expression op:except($seq2, $seq3)
returns ($item1)
.
The expression op:except($seq2, ())
returns ($item1, $item2)
.
The expression op:except($seq3, $seq2)
returns ($item3)
.
Aggregate functions take a sequence as argument and return a single value
computed from values in the sequence. Except for fn:count
, the
sequence must consist of values of a single type or one if its subtypes, or they
must be numeric. xs:untypedAtomic
values are permitted in the
input sequence and handled by special conversion rules. The type of the items in
the sequence must also support certain operations.
Function  Meaning 

fn:count  Returns the number of items in a sequence. 
fn:avg  Returns the average of the values in the input sequence $arg , that
is, the sum of the values divided by the number of values. 
fn:max  Returns a value that is equal to the highest value appearing in the input sequence. 
fn:min  Returns a value that is equal to the lowest value appearing in the input sequence. 
fn:sum  Returns a value obtained by adding together the values in
$arg . 
Returns the number of items in a sequence.
This function is
The function returns the number of items in the value of $arg
.
Returns 0 if $arg
is the empty sequence.
let $seq1
:= ($item1, $item2)
let $seq2
:= (98.5, 98.3, 98.9)
let $seq3
:= ()
The expression fn:count($seq1)
returns 2
.
The expression fn:count($seq3)
returns 0
.
The expression fn:count($seq2)
returns 3
.
The expression fn:count($seq2[. > 100])
returns 0
.
Returns the average of the values in the input sequence $arg
, that
is, the sum of the values divided by the number of values.
This function is
If $arg
is the empty sequence, the empty sequence is returned.
If $arg
contains values of type xs:untypedAtomic
they are cast
to xs:double
.
Duration values must either all be xs:yearMonthDuration
values or must all
be xs:dayTimeDuration
values. For numeric values, the numeric promotion
rules defined in $arg
must contain items of a single
type, which must be one of the four numeric types, xs:yearMonthDuration
or
xs:dayTimeDuration
or one if its subtypes.
The function returns the average of the values as sum($arg) div
count($arg)
; but the implementation may use an otherwise equivalent algorithm
that avoids arithmetic overflow.
For detailed type semantics, see [Formal Semantics].
A type error is raised
let $d1
:= xs:yearMonthDuration("P20Y")
let $d2
:= xs:yearMonthDuration("P10M")
let $seq3
:= (3, 4, 5)
The expression fn:avg($seq3)
returns 4.0
. xs:decimal
.).
The expression fn:avg(($d1, $d2))
returns xs:yearMonthDuration("P10Y5M")
.
fn:avg(($d1, $seq3))
raises a type error
The expression fn:avg(())
returns ()
.
The expression fn:avg((xs:float('INF'), xs:float('INF')))
returns xs:float('NaN')
.
The expression fn:avg(($seq3, xs:float('NaN')))
returns xs:float('NaN')
.
Returns a value that is equal to the highest value appearing in the input sequence.
The zeroargument form of this function is
The oneargument form of this function is
The following rules are applied to the input sequence $arg
:
Values of type xs:untypedAtomic
in $arg
are cast to
xs:double
.
Numeric and xs:anyURI
values are converted to
the least common type reachable by a combination of type promotion and subtype
substitution. See
The items in the resulting sequence may be reordered in an arbitrary order. The resulting sequence is referred to below as the converted sequence. The function returns an item from the converted sequence rather than the input sequence.
If the converted sequence is empty, the function returns the empty sequence.
All items in the le
operator is
defined. In addition, the values in the sequence must have a total order. If date/time
values do not have a timezone, they are considered to have the implicit timezone
provided by the dynamic context for the purpose of comparison. Duration values must
either all be xs:yearMonthDuration
values or must all be
xs:dayTimeDuration
values.
If the converted sequence contains the value NaN
, the value
NaN
is returned.
If the items in the xs:string
or types derived by restriction from xs:string
,
then the determination of the item with the smallest value is made according to the
collation that is used. If the type of the items in the xs:string
and
$collation
is specified, the collation is ignored.
The collation used by this function is determined according to the rules in
The function returns the result of the expression:
evaluated with $collation
as the default collation if specified, and with
$c
as the converted sequence.
For detailed type semantics, see [Formal Semantics].
A type error is raised
Because the rules allow the sequence to be reordered, if there are two or items that are
"equal highest", the specific item whose value is returned is xs:dateTime
values compare equal despite being in different timezones.
If the converted sequence contains exactly one value then that value is returned.
The default type when the fn:max
function is applied to
xs:untypedAtomic
values is xs:double
. This differs from the
default type for operators such as gt
, and for sorting in XQuery and XSLT,
which is xs:string
.
The expression fn:max((3,4,5))
returns 5
.
The expression fn:max((xs:integer(5), xs:float(5.0), xs:double(0)))
returns xs:double(5.0e0)
.
fn:max((3,4,"Zero"))
raises a type error
The expression fn:max((fn:currentdate(), xs:date("21000101")))
returns xs:date("21000101")
.
The expression fn:max(("a", "b", "c"))
returns "c"
.
Returns a value that is equal to the lowest value appearing in the input sequence.
The zeroargument form of this function is
The oneargument form of this function is
The following rules are applied to the input sequence:
Values of type xs:untypedAtomic
in $arg
are cast to
xs:double
.
Numeric and xs:anyURI
values are converted to
the least common type reachable by a combination of type promotion and subtype
substitution. See
The items in the resulting sequence may be reordered in an arbitrary order. The resulting sequence is referred to below as the converted sequence. The function returns an item from the converted sequence rather than the input sequence.
If the converted sequence is empty, the empty sequence is returned.
All items in the le
operator is
defined. In addition, the values in the sequence must have a total order. If date/time
values do not have a timezone, they are considered to have the implicit timezone
provided by the dynamic context for the purpose of comparison. Duration values must
either all be xs:yearMonthDuration
values or must all be
xs:dayTimeDuration
values.
If the converted sequence contains the value NaN
, the value
NaN
is returned.
If the items in the xs:string
or types derived by restriction from xs:string
,
then the determination of the item with the smallest value is made according to the
collation that is used. If the type of the items in the xs:string
and
$collation
is specified, the collation is ignored.
The collation used by this function is determined according to the rules in
The function returns the result of the expression:
evaluated with $collation
as the default collation if specified, and with
$c
as the converted sequence.
For detailed type semantics, see [Formal Semantics].
A type error is raised
Because the rules allow the sequence to be reordered, if there are two or items that are
"equal lowest", the specific item whose value is returned is xs:dateTime
values compare equal despite being in different timezones.
If the converted sequence contains exactly one value then that value is returned.
The default type when the fn:min
function is applied to
xs:untypedAtomic
values is xs:double
. This differs from the
default type for operators such as lt
, and for sorting in XQuery and XSLT,
which is xs:string
.
The expression fn:min((3,4,5))
returns 3
.
The expression fn:min((xs:integer(5), xs:float(5), xs:double(10)))
returns xs:double(5.0e0)
.
fn:min((3,4,"Zero"))
raises a type error
fn:min((xs:float(0.0E0), xs:float(0.0E0)))
can return either positive
or negative zero.
The expression fn:min((fn:currentdate(), xs:date("19000101")))
returns xs:date("19000101")
.
The expression fn:min(("a", "b", "c"))
returns "a"
.
Returns a value obtained by adding together the values in
$arg
.
This function is
Any values of type xs:untypedAtomic
in $arg
are cast to
xs:double
. The items in the resulting sequence may be reordered in an
arbitrary order. The resulting sequence is referred to below as the converted
sequence.
If the converted sequence is empty, then the singleargument form of the function
returns the xs:integer
value 0
; the twoargument form returns
the value of the argument $zero
.
If the converted sequence contains the value NaN
, NaN
is
returned.
All items in $arg
must be numeric or derived from a single base type. In
addition, the type must support addition. Duration values must either all be
xs:yearMonthDuration
values or must all be
xs:dayTimeDuration
values. For numeric values, the numeric promotion
rules defined in xs:double
will be an
xs:double
.
The result of the function, using the second signature, is the result of the expression:
where $c
is the converted sequence.
The result of the function, using the first signature, is the result of the expression:
fn:sum($arg, 0)
.
For detailed type semantics, see [Formal Semantics].
A type error is raised
The second argument allows an appropriate value to be defined to represent the sum of an empty sequence. For example, when summing a sequence of durations it would be appropriate to return a zerolength duration of the appropriate type. This argument is necessary because a system that does dynamic typing cannot distinguish "an empty sequence of integers", for example, from "an empty sequence of durations".
If the converted sequence contains exactly one value then that value is returned.
let $d1
:= xs:yearMonthDuration("P20Y")
let $d2
:= xs:yearMonthDuration("P10M")
let $seq1
:= ($d1, $d2)
let $seq3
:= (3, 4, 5)
The expression fn:sum(($d1, $d2))
returns xs:yearMonthDuration("P20Y10M")
.
The expression fn:sum($seq1[. lt xs:yearMonthDuration('P3M')],
xs:yearMonthDuration('P0M'))
returns xs:yearMonthDuration("P0M")
.
The expression fn:sum($seq3)
returns 12
.
The expression fn:sum(())
returns 0
.
The expression fn:sum((),())
returns ()
.
The expression fn:sum((1 to 100)[. lt 0], 0)
returns 0
.
fn:sum(($d1, 9E1))
raises a
The expression fn:sum(($d1, $d2), "ein Augenblick")
returns xs:yearMonthDuration("P20Y10M")
. $zero
value should be
the same type as the items in $arg
, or even that it should belong to
a type that supports addition.).
Function  Meaning 

op:to  Returns a sequence of consecutive integers in a given range. 
Returns a sequence of consecutive integers in a given range.
Defines the semantics of the "to" operator.
The function returns the sequence containing every xs:integer
whose value
is between the value of $firstval
(inclusive) and the value of
$lastval
(inclusive), in monotonic increasing order.
If the value of the first operand is greater than the value of the second, the function returns the empty sequence.
If the values of the two operands are equal, the function returns a sequence containing
a single xs:integer
equal to that value.
The expression 1 to 3
returns (1, 2, 3)
.
The expression 3 to 1
returns ()
.
The expression 5 to 5
returns 5
.
Returns the sequence of element nodes that have an ID
value
matching the value of one or more of the IDREF
values supplied in
$arg
.
The oneargument form of this function is
The twoargument form of this function is
The function returns a sequence, in document order with duplicates eliminated,
containing every element node E
that satisfies all the following
conditions:
E
is in the target document. The target document is the document
containing $node
, or the document containing the context item
(.
) if the second argument is omitted. The behavior of the
function if $node
is omitted is exactly the same as if the context
item had been passed as $node
.
E
has an ID
value equal to one of the candidate
IDREF
values, where:
An element has an ID
value equal to V
if either
or both of the following conditions are true:
The isid
property (See eq
operator using the Unicode codepoint collation
(http://www.w3.org/2005/xpathfunctions/collation/codepoint
).
The element has an attribute node whose isid
property
(See V
under the rules of the
eq
operator using the Unicode code point collation
(http://www.w3.org/2005/xpathfunctions/collation/codepoint
).
Each xs:string
in $arg
is parsed as if it were of
type IDREFS
, that is, each xs:string
in
$arg
is treated as a whitespaceseparated sequence of
tokens, each acting as an IDREF
. These tokens are then included
in the list of candidate IDREF
s. If any of the tokens is not a
lexically valid IDREF
(that is, if it is not lexically an
xs:NCName
), it is ignored. Formally, the candidate
IDREF
values are the strings in the sequence given by the
expression:
If several elements have the same ID
value, then E
is
the one that is first in document order.
A $node
, or the context item if the second argument is absent, is a node
in a tree whose root is not a document node.
If the second argument is the context item, or is omitted, the following
The effect of this function is anomalous in respect of element
nodes with the isid
property. For legacy reasons, this function returns
the element that has the isid
property, whereas it would be more
appropriate to return its parent, that being the element that is uniquely identified by
the ID. A new function
If the data model is constructed from an Infoset, an attribute will have the
isid
property if the corresponding attribute in the Infoset had an
attribute type of ID
: typically this means the attribute was declared as an
ID
in a DTD.
If the data model is constructed from a PSVI, an element or
attribute will have the isid
property if its typed value is a single
atomic value of type xs:ID
or a type derived by restriction from
xs:ID
.
No error is raised in respect of a candidate IDREF
value that does not
match the ID
of any element in the document. If no candidate
IDREF
value matches the ID
value of any element, the
function returns the empty sequence.
It is not necessary that the supplied argument should have type xs:IDREF
or xs:IDREFS
, or that it should be derived from a node with the
isidrefs
property.
An element may have more than one ID
value. This can occur with synthetic
data models or with data models constructed from a PSVI where the element and one of its
attributes are both typed as xs:ID
.
If the source document is wellformed but not valid, it is possible for two or more
elements to have the same ID
value. In this situation, the function will
select the first such element.
It is also possible in a wellformed but invalid document to have an element or
attribute that has the isid
property but whose value does not conform to
the lexical rules for the xs:ID
type. Such a node will never be selected by
this function.
let $emp
:=
The expression id('ID21256')/name()
returns employee
. xml:id
attribute has the isid
property,
so the employee element is selected.).
The expression id('E21256')/name()
returns empnr
. empnr
element is given the type
xs:ID
as a result of schema validation, the element will have the
isid
property and is therefore selected. Note the difference from
the behavior of fn:elementwithid
.).
Returns the sequence of element nodes that have an
ID
value matching the value of one or more of the IDREF
values supplied in $arg
.
The oneargument form of this function is
The twoargument form of this function is
The effect of this function is identical to isid
property. However,
it behaves differently in respect of element nodes with the isid
property. Whereas the fn:id
, for legacy reasons, returns the element
that has the isid
property, this parent returns the element
identified by the ID, which is the parent of the element having the
isid
property.
The function returns a sequence, in document order with duplicates eliminated,
containing every element node E
that satisfies all the following
conditions:
E
is in the target document. The target document is the document
containing $node
, or the document containing the context item
(.
) if the second argument is omitted. The behavior of the
function if $node
is omitted is exactly the same as if the context
item had been passed as $node
.
E
has an ID
value equal to one of the candidate
IDREF
values, where:
An element has an ID
value equal to V
if
either or both of the following conditions are true:
The element has an child element node whose isid
property (See V
under the rules of the
eq
operator using the Unicode code point collation
(http://www.w3.org/2005/xpathfunctions/collation/codepoint
).
The element has an attribute node whose isid
property
(See V
under the rules of the
eq
operator using the Unicode code point collation
(http://www.w3.org/2005/xpathfunctions/collation/codepoint
).
Each xs:string
in $arg
is parsed as if it were
of type IDREFS
, that is, each xs:string
in
$arg
is treated as a whitespaceseparated sequence of
tokens, each acting as an IDREF
. These tokens are then
included in the list of candidate IDREF
s. If any of the
tokens is not a lexically valid IDREF
(that is, if it is not
lexically an xs:NCName
), it is ignored. Formally, the
candidate IDREF
values are the strings in the sequence given
by the expression:
If several elements have the same ID
value, then E
is the one that is first in document order.
A $node
, or the context item if the second argument is omitted, is a
node in a tree whose root is not a document node.
If the second argument is the context item, or is omitted, the following
This function is equivalent to the fn:id
function except when dealing with
IDvalued element nodes. Whereas the fn:id
function selects the element
containing the identifier, this function selects its parent.
If the data model is constructed from an Infoset, an attribute will have the
isid
property if the corresponding attribute in the Infoset had an
attribute type of ID
: typically this means the attribute was declared as an
ID
in a DTD.
If the data model is constructed from a PSVI, an element or
attribute will have the isid
property if its typed value is a single
atomic value of type xs:ID
or a type derived by restriction from
xs:ID
.
No error is raised in respect of a candidate IDREF
value that does not
match the ID
of any element in the document. If no candidate
IDREF
value matches the ID
value of any element, the
function returns the empty sequence.
It is not necessary that the supplied argument should have type xs:IDREF
or xs:IDREFS
, or that it should be derived from a node with the
isidrefs
property.
An element may have more than one ID
value. This can occur with synthetic
data models or with data models constructed from a PSVI where the element and one of its
attributes are both typed as xs:ID
.
If the source document is wellformed but not valid, it is possible for two or more
elements to have the same ID
value. In this situation, the function will
select the first such element.
It is also possible in a wellformed but invalid document to have an element or
attribute that has the isid
property but whose value does not conform to
the lexical rules for the xs:ID
type. Such a node will never be selected by
this function.
let $emp
:=
The expression id('ID21256')/name()
returns "employee"
. xml:id
attribute has the isid
property,
so the employee element is selected.).
The expression id('E21256')/name()
returns "employee"
. empnr
element is given the type
xs:ID
as a result of schema validation, the element will have the
isid
property and is therefore its parent is selected. Note the
difference from the behavior of fn:id
.).
Returns the sequence of element or attribute nodes with an IDREF
value matching the value of one or more of the ID
values supplied in
$arg
.
The oneargument form of this function is
The twoargument form of this function is
The function returns a sequence, in document order with duplicates eliminated,
containing every element or attribute node $N
that satisfies all the
following conditions:
$N
is in the target document. The target document is the document
containing $node
or the document containing the context item
(.
) if the second argument is omitted. The behavior of the
function if $node
is omitted is exactly the same as if the context
item had been passed as $node
.
$N
has an IDREF
value equal to one of the candidate
ID
values, where:
A node $N
has an IDREF
value equal to
V
if both of the following conditions are true:
The isidrefs
property (see $N
is true
.
The sequence V
under the rules of the eq
operator using the Unicode code point collation
(http://www.w3.org/2005/xpathfunctions/collation/codepoint
).
Each xs:string
in $arg
is parsed as if it were of
lexically of type xs:ID
. These xs:string
s are then
included in the list of candidate xs:ID
s. If any of the strings
in $arg
is not a lexically valid xs:ID
(that is,
if it is not lexically an xs:NCName
), it is ignored. More
formally, the candidate ID
values are the strings in the
sequence:
A $node
, or the context item if the second argument is omitted, is a node
in a tree whose root is not a document node.
If the second argument is the context item, or is omitted, the following errors may be
raised: if the context item is
An element or attribute typically acquires the isidrefs
property by being
validated against the schema type xs:IDREF
or xs:IDREFS
, or
(for attributes only) by being described as of type IDREF
or
IDREFS
in a DTD.
No error is raised in respect of a candidate ID
value that does not match
the IDREF
value of any element or attribute in the document. If no
candidate ID
value matches the IDREF
value of any element or
attribute, the function returns the empty sequence.
It is possible for two or more nodes to have an IDREF
value that matches a
given candidate ID
value. In this situation, the function will return all
such nodes. However, each matching node will be returned at most once, regardless how
many candidate ID
values it matches.
It is possible in a wellformed but invalid document to have a node whose
isidrefs
property is true but that does not conform to the lexical
rules for the xs:IDREF
type. The effect of the above rules is that
illformed candidate ID
values and illformed IDREF
values are
ignored.
If the data model is constructed from a PSVI, the typed value of a
node that has the isidrefs
property will contain at least one atomic value
of type xs:IDREF
(or a type derived by restriction from
xs:IDREF
). It may also contain atomic values of other types. These
atomic values are treated as candidate ID
values if their lexical form is
valid as an xs:NCName
, and they are ignored otherwise.
This function returns a string that uniquely identifies a given node.
The zeroargument form of this function is
The oneargument form of this function is
If the argument is omitted, it defaults to the context item (.
). The
behavior of the function if the argument is omitted is exactly the same as if the
context item had been passed as the argument.
If the argument is the empty sequence, the result is the zerolength string.
In other cases, the function returns a string that uniquely identifies a given node.
The returned identifier
An implementation is free to generate an identifier in any convenient way provided that it always generates the same identifier for the same node and that different identifiers are always generated from different nodes. An implementation is under no obligation to generate the same identifiers each time a document is transformed or queried.
The following errors may be raised when $arg
is omitted: if the context
item is
There is no guarantee that a generated unique identifier will be distinct from any unique IDs specified in the source document.
There is no inverse to this function; it is not directly possible to find the node with
a given generated ID. Of course, it is possible to search a given sequence of nodes
using an expression such as $nodes[generateid()=$id]
.
It is advisable, but not required, for implementations to generate IDs that are distinct even when compared using a caseblind collation.
The primary use case for this function is to generate hyperlinks. For example, when
generating HTML, an anchor for a given section $sect
can be generated by
writing (in either XSLT or XQuery):
<a name="{generateid($sect)}"/>
and a link to that section can then be produced with code such as:
see <a href="#{generateid($sect)}">here</a>
Note that anchors generated in this way will not necessarily be the same each time a document is republished.
Retrieves a document using a URI supplied as an
xs:string
, and returns the corresponding document node.
This function is
If $uri
is the empty sequence, the result is an empty sequence.
If $uri
is a relative URI reference, it is resolved
relative to the value of the xs:string
.
If the
The URI may include a fragment identifier.
By default, this function is
However, for performance reasons, implementations may provide a user option to evaluate
the function without a guarantee of determinism. The manner in which any such option is
provided is implementationdefined. If the user has not selected such an option, a call
of the function must either return a deterministic result or must raise a
For detailed type semantics, see [Formal Semantics].
If $uri
is read from a source document, it is generally appropriate to
resolve it relative to the base URI property of the relevant node in the source
document. This can be achieved by calling the fn:resolveuri
function,
and passing the resulting absolute URI as an argument to the fn:doc
function.
If two calls to this function supply different absolute URI References as arguments, the same document node may be returned if the implementation can determine that the two arguments refer to the same resource.
By defining the semantics of this function in terms of a stringtodocumentnode
mapping in the dynamic context, the specification is acknowledging that the results of
this function are outside the purview of the language specification itself, and depend
entirely on the runtime environment in which the expression is evaluated. This runtime
environment includes not only an unpredictable collection of resources ("the web"), but
configurable machinery for locating resources and turning their contents into document
nodes within the XPath data model. Both the set of resources that are reachable, and the
mechanisms by which those resources are parsed and validated, are
One possible processing model for this function is as follows. The resource identified
by the URI Reference is retrieved. If the resource cannot be retrieved, a
Various aspects of this processing are
The set of URI schemes that the implementation recognizes is implementationdefined. Implementations may allow the mapping of URIs to resources to be configured by the user, using mechanisms such as catalogs or userwritten URI handlers.
The handling of nonXML media types is implementationdefined. Implementations may allow instances of the data model to be constructed from nonXML resources, under user control.
It is
Implementations may provide userdefined error handling options that allow processing to continue following an error in retrieving a resource, or in parsing and validating its content. When errors have been handled in this way, the function may return either an empty sequence, or a fallback document provided by the error handler.
Implementations may provide user options that relax the requirement for the function to return deterministic results.
A $uri
is not a valid URI.
A
A
A
The function returns true if and only if the function
call fn:doc($uri)
would return a document node.
This function is
If $uri
is an empty sequence, this function returns
false
.
If a call on fn:doc($uri)
would return a document
node, this function returns true
.
A $uri
is not a valid URI according to the rules applied by the
implementation of fn:doc
.
Otherwise, this function returns false
.
If this function returns true
, then calling fn:doc($uri)
within the same fn:doc
function,
this guarantee is lost.
Returns a sequence of nodes representing a collection of documents indentified by a collection URI; or a default collection if no URI is supplied.
This function is
This function takes an xs:string
as argument and returns a sequence of
nodes obtained by interpreting $arg
as an xs:anyURI
and
resolving it according to the mapping specified in
If
If $arg
is not specified, the function returns the sequence of the nodes in
the default node collection in the dynamic context. See
If the value of $arg
is a relative xs:anyURI
, it is resolved
against the value of the baseURI property from the static context.
If $arg
is the empty sequence, the function behaves as if it had been
called without an argument. See above.
By default, this function is
There is no requirement that the returned nodes should be in document order, nor is there a requirement that the result should contain no duplicates.
For detailed type semantics, see [Formal Semantics].
A
An error is raised
A $arg
is not a
valid xs:anyURI
.
This function provides a facility for users to work with a collection of documents
which may be contained in a directory, or in the rows of a relational table, or in some other
implementationspecific construct. An implementation may also use external variables to
identify external resources, but fn:collection
provides functionality not
provided by external variables. Specifying resources using URIs is useful because URIs
are dynamic, can be parameterized, and do not rely on an external environment.
Returns a sequence of xs:anyURI
values representing the URIs in a resource collection.
This function is
The zeroargument form of the function returns the URIs in the
If the value of $arg
is a relative xs:anyURI
, it is resolved
against the value of the baseURI property from the static context.
If $arg
is the empty sequence, the function behaves as if it had been
called without an argument. See above.
The singleargument form of the function returns the sequence of URIs corresponding to the
supplied URI in the
A
A
A $arg
is not a
valid xs:anyURI
.
There are several reasons why it might be appropriate to use this function in preference
to the fn:collection
function:
It allows resources to be retrieved that are not wellformed XML documents: for
example, the returned URIs might be referenced using the fn:unparsedtext
function rather than the fn:doc
function.
In XSLT 3.0 it allows the documents to be processed in streaming mode using the
xsl:stream
instruction.
It allows recovery from failures to read, parse, or validate individual documents,
by calling the fn:doc
function within the scope of try/catch.
It allows selection of which documents to read based on their URI, for example
they can be filtered to select those whose URIs end in .xml
,
or those that use the https
scheme.
An application might choose to limit the number of URIs processed in a single run, for example it might process only the first 50 URIs in the collection; or it might present the URIs to the user and allow the user to select which of them need to be further processed.
It allows the URIs to be modified before they are dereferenced, for example by adding or removing query parameters, or by redirecting the request to a local cache or to a mirror site.
For some of these use cases, this assumes that the cost of calling fn:collection
might be significant (for example, it might involving retrieving all the documents in the collection over the
network and parsing them). This will not necessarily be true of all implementations.
Some implementations might ensure that calling fn:uricollection
and then applying
fn:doc
to each of the returned URIs delivers the same result as calling fn:collection
with the same argument; however, this is not guaranteed.
There is no requirement that the URIs returned by this function should all be distinct, and no assumptions can be made about the order of URIs in the sequence, unless the implementation defines otherwise.
The fn:unparsedtext
function reads an external resource (for example, a
file) and returns
This function is
The $href
argument
The mapping of URIs to the string representation of a resource is the mapping defined
in the
If the value of the $href
argument is an empty sequence, the function
returns an empty sequence.
The $encoding
argument, if present, is the name of an encoding. The values
for this attribute follow the same rules as for the encoding
attribute in
an XML declaration. The only values which every utf8
and utf16
.
The encoding of the external resource is determined as follows:
external encoding information is used if available, otherwise
if the media type of the resource is text/xml
or
application/xml
(see text/*+xml
or application/*+xml
(see
the value of the $encoding
argument is used if present, otherwise
the processor
UTF8 is assumed.
The result of the function is a string containing the
A $href
contains a fragment identifier, or if it cannot be used to retrieve the
A $encoding
argument is not a valid encoding name,
A $encoding
is absent and the
If it is appropriate to use a base URI other than the fn:resolveuri
function before
passing it to the
There is no essential relationship between the sets of URIs accepted by
the two functions fn:unparsedtext
and fn:doc
(a URI accepted by one may or may
not be accepted by the other), and if a URI is accepted by both there is no
essential relationship between the results (different resource representations
are permitted by the architecture of the web).
There are no constraints on the MIME type of the resource.
The fact that the resolution of URIs is defined by a mapping
in the dynamic context means that in effect, various aspects of the behavior of this
function are
The set of URI schemes that the implementation recognizes is implementationdefined. Implementations may allow the mapping of URIs to resources to be configured by the user, using mechanisms such as catalogs or userwritten URI handlers.
The handling of media types is implementationdefined.
Implementations may provide userdefined error handling options that allow processing to continue following an error in retrieving a resource, or in reading its content. When errors have been handled in this way, the function may return a fallback document provided by the error handler.
Implementations may provide user options that relax the requirement for the function to return deterministic results.
The rules for determining the encoding are chosen for consistency with
If the text file contains characters such as <
and &
,
these will typically be output as <
and &
if
the string is serialized as XML or HTML. If these characters actually represent markup (for
example, if the text file contains HTML), then an XSLT stylesheet can attempt to write
them as markup to the output file using the disableoutputescaping
attribute of the xsl:valueof
instruction. Note, however, that XSLT
implementations are not required to support this feature.
This XSLT example attempts to read a file containing 'boilerplate' HTML and copy it directly to the serialized output file:
The fn:unparsedtextlines
function reads an external resource (for
example, a file) and returns its contents as a sequence of strings, one for each line of
text in the
This function is
The unparsedtextlines
function reads an external resource (for example, a
file) and returns its
The result of the singleargument function is the same as the result of the expression
fn:tokenize(fn:unparsedtext($href), '\r\n\r\n')[not(position()=last() and
.='')]
. The result of the twoargument function is the same as the result of
the expression fn:tokenize(fn:unparsedtext($href, $encoding),
'\r\n\r\n'))[not(position()=last() and .='')]
.
The result is a thus a sequence of strings containing the text of the resource retrieved using the URI, each string representing one line of text. Lines are separated by one of the sequences x0A, x0D, or x0Dx0A. The characters representing the newline are not included in the returned strings. If there are two adjacent newline sequences, a zerolength string will be returned to represent the empty line; but if the external resource ends with a newline sequence, no zerolength string will be returned as the last item in the result.
Error conditions are the same as for the fn:unparsedtext
function.
See the notes for fn:unparsedtext
.
Because errors in evaluating the
This function is
The
If the first argument is an empty sequence, the function returns false.
In other cases, the function returns true if a call on
The functions fn:doc
and fn:docavailable
. This means that unless the
user has explicitly stated a requirement for a reduced level of determinism, either of
these functions if called twice with the same arguments during the course of a
transformation
This requires that the if (unparsedtextavailable(A)) then unparsedtext(A) else ...
to
generate a single call internally.
Returns the value of a system environment variable, if it exists.
This function is
The set of available
If the $name
argument matches the name of one of these pairs, the function
returns the corresponding value.
If there is no environment variable with a matching name, the function returns the empty sequence.
The collation used for matching names is
The function is
On many platforms, the term "environment variable" has a natural meaning in terms of facilities provided by the operating system. This interpretation of the concept does not exclude other interpretations, such as a mapping to a set of configuration parameters in a database system.
Environment variable names are usually case sensitive. Names are usually of the form
(letter_) (letter_digit)*
, but this varies by platform.
On some platforms, there may sometimes be multiple environment variables with the same name;
in this case, it is implementationdependent as to which is returned; see for example
The requirement to ensure that the function is deterministic means in practice that the implementation must make a snapshot of the environment variables at some time during execution, and return values obtained from this snapshot, rather than using live values that are subject to change at any time.
Operating system environment variables may be associated with a particular process,
while queries and stylesheets may execute across multiple processes (or multiple machines).
In such circumstances implementations
Security advice: Queries from untrusted sources should not be permitted unrestricted
access to environment variables. For example, the name of the account under which the
query is running may be useful information to a wouldbe intruder. An implementation may
therefore choose to restrict access to the environment, or may provide a facility to
make fn:environmentvariable
always return the empty sequence.
Returns a list of environment variable names that are suitable for passing to
fn:environmentvariable
, as a (possibly empty) sequence of strings.
This function is
The function returns a sequence of strings, being the names of the environment variables
in the dynamic context in some
The function is
The function returns a list of strings, containing no duplicates.
It is intended that the strings in this list should be suitable for passing to
fn:environmentvariable
.
See also the note on security under the definition of the
fn:environmentvariable
function. If access to environment variables has
been disabled, fn:availableenvironmentvariables
always returns the empty
sequence.
This function takes as input an XML document represented as a string, and returns the document node at the root of an XDM tree representing the parsed document.
This function is
If $arg
is the empty sequence, the function returns the
empty sequence.
The precise process used to construct the XDM instance is
The Static Base URI property from the static context of the
fn:parsexml
function call is used both as the base URI used by the XML parser to resolve
relative entity references within the document, and as the base URI of the document node
that is returned.
The document URI of the returned node is
The function is
A $arg
is not a wellformed and namespacewellformed XML document.
A $arg
is not valid against its
DTD.
Since the XML document is presented to the parser as a string, rather than as a sequence of octets, the encoding specified within the XML declaration has no meaning. If the XML parser accepts input only in the form of a sequence of octets, then the processor must ensure that the string is encoded as octets in a way that is consistent with rules used by the XML parser to detect the encoding.
The primary use case for this function is to handle input documents that contain nested
XML documents embedded within CDATA sections. Since the content of the CDATA section are
exposed as text, the receiving query or stylesheet may pass this text to the
fn:parsexml
function to create a tree representation of the nested
document.
Similarly, nested XML within comments is sometimes encountered, and lexical XML is sometimes returned by extension functions, for example, functions that access web services or read from databases.
A use case arises in XSLT where there is a need to preprocess an input document before
parsing. For example, an application might wish to edit the document to remove its
DOCTYPE declaration. This can be done by reading the raw text using the
fn:unparsedtext
function, editing the resulting string, and then
passing it to the fn:parsexml
function.
The expression fn:parsexml("<alpha>abcd</alpha>")
returns a newly
created document node, having an alpha
element as its only child; the
alpha
element in turn is the parent of a text node whose string value
is "abcd"
.
This function takes as input an XML external entity represented as a string, and returns the document node at the root of an XDM tree representing the parsed document fragment.
This function is
If $arg
is the empty sequence, the function returns the empty sequence.
The input must be a namespacewellformed external general parsed entity. More specifically,
it must be a string conforming to the production rule
The string is parsed to form a sequence of nodes which become children of the new document node, in the same way as the content of any element is converted into a sequence of children for the resulting element node.
Schema validation is
The precise process used to construct the XDM instance is
The Static Base URI from the static context of the fn:parsexmlfragment
function call
is used as the base URI of the document node
that is returned.
The document URI of the returned node is
The function is
A $arg
is not a wellformed external general parsed entity,
if it contains entity references other than references to predefined entities, or if a document that
incorporates this wellformed parsed entity would not be namespacewellformed.
See also the notes for the fn:parsexml
function.
The main differences between fn:parsexml
and
fn:parsexmlfragment
are that for fn:parsexml
, the
children of the resulting document node must contain exactly one element node and no
text nodes, wheras for fn:parsexmlfragment
, the resulting document node
can have any number (including zero) of element and text nodes among its children. An
additional difference is that the
Note that all whitespace outside the
One use case for this function is to handle XML fragments stored in databases,
which frequently allow zeroormore top level element nodes. Another use case
is to parse the contents of a CDATA
section embedded within another XML document.
The expression fn:parsexmlfragment("<alpha>abcd</alpha><beta>abcd</beta>")
returns a newly
created document node, having two elements named alpha
and beta
as its children; each of these elements in turn is the parent of a text node.
The expression fn:parsexmlfragment("He was <i>so</i> kind")
returns a newly
created document node having three children: a text node whose string value is
"He was "
, an element node named i
having a child text
node with string value "so"
, and a text node whose string value is
" kind"
.
The expression fn:parsexmlfragment("")
returns a document node
having no children.
The expression fn:parsexmlfragment(" ")
returns a document node
whose children comprise a single text node whose string value is a single space.
The expression fn:parsexmlfragment('<xml version="1.0" encoding="utf8" standalone="yes"?></a>")
results in a fn:parsexml
function will also be accepted by fn:parsexmlfragment
.)
This function serializes the supplied $arg
as described in
This function is
The value of $arg
acts as the input sequence to the serialization process,
which starts with sequence normalization.
The singleargument version of this function has the same effect as
the twoargument version called with $params
set to an empty sequence. This
in turn is the same as the effect of passing an
output:serializationparameters
element with no child elements.
The $params
argument is used to identify a set of
serialization parameters. These are supplied in the form of an
output:serializationparameters
element, having the format described in
The final stage of serialization, that is, encoding, is skipped. If the serializer does not allow this phase to be skipped, then the sequence of octets returned by the serializer is decoded into a string by reversing the character encoding performed in the final stage.
If the host language makes serialization an optional feature and
the implementation does not support serialization, then a dynamic error
The serialization process will raise an error if $arg
is an attribute or
namespace node.
If any serialization error occurs, including the detection of an invalid value for a
serialization parameter, this results in the fn:serialize
call failing with
a dynamic error.
One use case for this function arises when there is a need to construct an XML document
containing nested XML documents within a CDATA section (or on occasions within a
comment). See fn:parsexml
for further details.
Another use case arises when there is a need to call an extension function that expects a lexical XML document as input.
There are also use cases where the application wants to postprocess the output of a
query or transformation, for example by adding an internal DTD subset, or by inserting
proprietary markup delimiters such as the <% ... %>
used by some
templating languages.
Given the output parameters:
let $params
:=
let $data
:=
The following call might produce the output shown:
The expression fn:serialize($data, $params)
returns '<a b="3"/>'
.
The following functions are defined to obtain information from the
Function  Meaning 

fn:position  Returns the context position from the dynamic context. 
fn:last  Returns the context size from the dynamic context. 
fn:currentdateTime  Returns the current date and time (with timezone). 
fn:currentdate  Returns the current date. 
fn:currenttime  Returns the current time. 
fn:implicittimezone  Returns the value of the implicit timezone property from the dynamic context. 
fn:defaultcollation  Returns the value of the default collation property from the static context. 
fn:staticbaseuri  This function returns the value of the Static Base URI property from the static context. 
Returns the context position from the dynamic context.
This function is
Returns the context position from the dynamic context. (See
An error is raised
Returns the context size from the dynamic context.
This function is
Returns the context size from the dynamic context. (See
An error is raised
The expression (1 to 20)[fn:last()  1]
returns 19
.
Returns the current date and time (with timezone).
This function is
Returns the current dateTime (with timezone) from the dynamic context. (See xs:dateTime
that is current at some time during the evaluation of a
query or transformation in which fn:currentdateTime
is executed.
This function is fn:currentdateTime()
is
If the implementation supports data types from XSD 1.1 then the
returned value will be an instance of xs:dateTimeStamp
. Otherwise, the only
guarantees are that it will be an instance of xs:dateTime
and will have a
timezone component.
The returned xs:dateTime
will always have an associated timezone, which
will always be the same as the implicit timezone in the dynamic context
fn:currentdateTime()
returns an xs:dateTimeStamp
corresponding to the current date and time. For example, a call of
fn:currentdateTime()
might return
20040512T18:17:15.125Z
corresponding to the current time on May 12,
2004 in timezone Z
.
Returns the current date.
This function is
Returns xs:date(fn:currentdateTime())
. This is an xs:date
(with timezone) that is current at some time during the evaluation of a query or
transformation in which fn:currentdate
is executed.
This function is fn:currentdate
is
The returned date will always have an associated timezone, which will always be the same as the implicit timezone in the dynamic context
fn:currentdate()
returns an xs:date
corresponding to the
current date. For example, a call of fn:currentdate()
might return
20040512+01:00
.
Returns the current time.
This function is
Returns xs:time(fn:currentdateTime())
. This is an xs:time
(with timezone) that is current at some time during the evaluation of a query or
transformation in which fn:currenttime
is executed.
This function is fn:currenttime()
is
The returned time will always have an associated timezone, which will always be the same as the implicit timezone in the dynamic context
fn:currenttime()
returns an xs:time
corresponding to the
current time. For example, a call of fn:currenttime()
might return
23:17:00.00005:00
.
Returns the value of the implicit timezone property from the dynamic context.
This function is
Returns the value of the implicit timezone property from the dynamic context. Components
of the dynamic context are discussed in
Returns the value of the default collation property from the static context.
This function is
Returns the value of the default collation property from the static context. Components
of the static context are discussed in
The default collation property can never be absent. If it is not explicitly defined, a
system defined default can be invoked. If this is not provided, the Unicode codepoint
collation (http://www.w3.org/2005/xpathfunctions/collation/codepoint
) is
used.
This function returns the value of the Static Base URI property from the static context.
This function is
The function returns the value of the Static Base URI property from the static context. If the property is absent, the empty sequence is returned.
Components of the static context are discussed in
XQuery 3.0 and XSLT 3.0 give an implementation freedom to use different base URIs during the
static analysis phase and the dynamic evaluation phase, that is, for compiletime and runtime resources respectively.
In this situation, the fn:staticbaseuri
function should return a URI suitable for locating resources needed
during dynamic evaluation.
The following functions operate on function items, that is, values referring to a function.
Function  Meaning 

fn:functionlookup  Returns the function having a given name and arity, if there is one. 
fn:functionname  Returns the name of the function identified by a function item. 
fn:functionarity  Returns the arity of the function identified by a function item. 
Returns the function having a given name and arity, if there is one.
This function is
If $functionname
and $functionarity
identify a named function
that is present in the dynamic context, then
a function item corresponding to that named function is returned.
Otherwise (if no known function can be identified by name and arity), an empty sequence is returned.
If the arguments to fn:functionlookup
identify a function that is present
in the static context of the function call, the function will always return the same function
that a static reference to this function would bind to. If there is no such function in the
static context, then the results depend on what is present in the dynamic context, which
is
If the function that is identified is
fn:functionlookup
returns a function whose name and signature match those of the requested function, but
whose implementation is a call on the fn:error
function, so that any attempt to
call the returned function fails with a dynamic error.
This function can be useful where there is a need to make a dynamic decision on which of several staticallyknown functions to call. It can thus be used as a substitute for polymorphism, in the case where the application has been designed so several functions implement the same interface.
The function can also be useful in cases where a query or stylesheet module is written to work
with alternative versions of a library module. In such cases the author of the main module might wish to
test whether an imported library module contains or does not contain a particular function, and to
call a function in that module only if it is available in the version that was imported. A static
call would cause a static error if the function is not available, whereas getting the function
using fn:functionlookup
allows the caller to take fallback action in this situation.
If the function that is retrieved by fn:functionlookup
has dependencies
on the static or dynamic context, the context that applies is the static and/or dynamic context of the
call to the fn:functionlookup
function itself. The context thus effectively forms part of the
closure of the returned function.
The expression fn:functionlookup(xs:QName('fn:substring'), 2)('abcd', 2)
returns 'bcd'
.
The expression (fn:functionlookup(xs:QName('xs:dateTimeStamp'), 1), xs:dateTime#1)[1] ('20111111T11:11:11Z')
returns an xs:dateTime
value set to the specified date, time, and timezone; if the implementation supports
XSD 1.1 then the result will be an instance of the derived type xs:dateTimeStamp
. The query is written to
ensure that no failure occurs when the implementation does not recognize the type xs:dateTimeStamp
.
The expression (let $f := fn:functionlookup(xs:QName('zip:binaryentry', 2)
return if (exists($f)) then $f($href, $entry) else ()
returns the result of calling
zip:binaryentry($href, $entry)
if the function is available, or an empty sequence
otherwise.
Returns the name of the function identified by a function item.
This function is
If $func
refers to a named function, fn:functionname($func)
returns the name of that function.
Otherwise ($func
refers to an anonymous function),
fn:functionname($func)
returns an empty sequence.
The prefix part of the returned QName is
The expression fn:functionname(fn:substring#2)
returns fn:QName("http://www.w3.org/2005/xpathfunctions",
"fn:substring")
.
The expression fn:functionname(function($node){count($node/*)})
returns ()
.
Returns the arity of the function identified by a function item.
This function is
The fn:functionarity
function returns the arity (number of arguments) of
the function identified by $func
.
The expression fn:functionarity(fn:substring#2)
returns 2
.
The expression fn:functionarity(function($node){name($node)})
returns 1
.
The expression let $initial := fn:substring(?, 1, 1) return fn:functionarity($initial)
returns 1
.
The following functions take function items as an argument.
Function  Meaning 

fn:map  Applies the function item $f to every item from the sequence $seq in turn, returning the concatenation of the resulting sequences in order. 
fn:filter  Returns those items from the sequence $seq for which the supplied function $f returns true. 
fn:foldleft  Processes the supplied sequence from left to right, applying the supplied function repeatedly to each item in turn, together with an accumulated result value. 
fn:foldright  Processes the supplied sequence from right to left, applying the supplied function repeatedly to each item in turn, together with an accumulated result value. 
fn:mappairs  Applies the function item $f to successive pairs of items taken one from $seq1 and one from $seq2, returning the concatenation of the resulting sequences in order. 
Applies the function item $f to every item from the sequence $seq in turn, returning the concatenation of the resulting sequences in order.
This function is
The effect of the function is equivalent to the following implementation in XQuery:
or its equivalent in XSLT:
The function call fn:map($F, $SEQ)
is equivalent to the expression
for $i in $SEQ return $F($i)
ordered
.
The expression fn:map(function($a) { $a * $a }, 1 to 5)
returns (1, 4, 9, 16, 25)
.
The expression fn:map(fn:stringtocodepoints#1, ("john", "jane"))
returns (106, 111, 104, 110, 106, 97, 110, 101)
.
The expression fn:map(xs:int#1, ("23", "29"))
returns (23, 29)
.
Returns those items from the sequence $seq for which the supplied function $f returns true.
This function is
The effect of the function is equivalent to the following implementation in XQuery:
or its equivalent in XSLT:
As a consequence of the function signature and the function calling
rules, a type error occurs if the supplied function $f returns anything other
than a single xs:boolean
item; there is no conversion to an effective
boolean value.
The function call fn:filter($F, $SEQ)
has a very similar effect to the
expression $SEQ[$F(.)]
. There are some differences, however. In the case of
fn:filter
, the function $F
is required to return a boolean;
there is no special treatment for numeric predicate values, and no conversion to an
effective boolean value. Also, with a filter expression $SEQ[$F(.)]
, the
focus within the predicate is different from that outside; this means that the use of
a contextsensitive function such as fn:lang#1
will give different results
in the two cases.
The expression fn:filter(function($a) {$a mod 2 = 0}, 1 to 10)
returns (2, 4, 6, 8, 10)
.
Processes the supplied sequence from left to right, applying the supplied function repeatedly to each item in turn, together with an accumulated result value.
This function is
The effect of the function is equivalent to the following implementation in XQuery:
or its equivalent in XSLT:
As a consequence of the function signature and the function calling rules, a type error occurs if the supplied function $f cannot be applied to two arguments, where the first argument is either the value of $zero or the result of a previous application of $f, and the second is $seq or any trailing subsequence of $seq.
This operation is often referred to in the functional programming literature as "folding" or "reducing" a sequence. It takes a function that operates on a pair of values, and applies it repeatedly, with an accumulated result as the first argument, and the next item in the sequence as the second argument. The accumulated result is initially set to the value of the $zero argument, which is conventionally a value (such as zero in the case of addition, one in the case of multiplication, or a zerolength string in the case of string concatenation) that causes the function to return the value of the other argument unchanged.
The expression fn:foldleft(function($a, $b) { $a + $b }, 0, 1 to
5)
returns 15
.
The expression fn:foldleft(function($a, $b) { $a * $b }, 1,
(2,3,5,7))
returns 210
.
The expression fn:foldleft(function($a, $b) { $a or $b }, false(), (true(),
false(), false()))
returns true()
.
The expression fn:foldleft(function($a, $b) { $a and $b }, false(), (true(),
false(), false()))
returns false()
.
The expression fn:foldleft(function($a, $b) {($b, $a)}, (), 1 to
5)
returns (5,4,3,2,1)
.
The expression fn:foldleft(fn:concat(?, ".", ?), "", 1 to 5)
returns ".1.2.3.4.5"
.
The expression fn:foldleft(fn:concat("$f(", ?, ", ", ?, ")"), "$zero", 1 to
5)
returns "$f($f($f($f($f($zero, 1), 2), 3), 4), 5)"
.
Processes the supplied sequence from right to left, applying the supplied function repeatedly to each item in turn, together with an accumulated result value.
This function is
The effect of the function is equivalent to the following implementation in XQuery:
or its equivalent in XSLT:
As a consequence of the function signature and the function calling rules, a type error occurs if the supplied function $f cannot be applied to two arguments, where the first argument is any item in the sequence $seq, and the second is either the value of $zero or the result of a previous application of $f.
This operation is often referred to in the functional programming literature as "folding" or "reducing" a sequence. It takes a function that operates on a pair of values, and applies it repeatedly, with the next item in the sequence as the first argument, and the result of processing the remainder of the sequence as the second argument. The accumulated result is initially set to the value of the $zero argument, which is conventionally a value (such as zero in the case of addition, one in the case of multiplication, or a zerolength string in the case of string concatenation) that causes the function to return the value of the other argument unchanged.
In cases where the function performs an associative operation on its two arguments (such
as addition or multiplication), fn:foldright
produces the same result as
fn:foldleft
.
The expression fn:foldright(function($a, $b) { $a + $b }, 0, 1 to
5)
returns 15
.
The expression fn:foldright(fn:concat(?, ".", ?), "", 1 to 5)
returns "1.2.3.4.5."
.
The expression fn:foldright(concat("$f(", ?, ", ", ?, ")"), "$zero", 1 to
5)
returns "$f(1, $f(2, $f(3, $f(4, $f(5, $zero)))))"
.
Applies the function item $f to successive pairs of items taken one from $seq1 and one from $seq2, returning the concatenation of the resulting sequences in order.
This function is
The effect of the function is equivalent to the following implementation in XQuery:
or its equivalent in XSLT:
The expression fn:mappairs(concat#2, ("a", "b", "c"), ("x", "y",
"z"))
returns ("ax", "by", "cz")
.
The expression fn:mappairs(function($a, $b){10*$a + $b}, 1 to 5, 1 to
5)
returns (11, 22, 33, 44, 55)
.
Every builtin atomic
type that is defined in xs:anyAtomicType
and xs:NOTATION
, has an
associated constructor function. The type xs:untypedAtomic
, defined
in xs:yearMonthDuration
and xs:dayTimeDuration
defined
in xs:dateTimeStamp
introduced in
A constructor function is not defined for xs:anyAtomicType
as there are no atomic values with type annotation xs:anyAtomicType
at runtime, although this can be a statically inferred type.
A constructor function is not defined for xs:NOTATION
since it is defined as an abstract type in xs:NOTATION
then a constructor function is defined for it.
See
The form of the constructor function for
If $arg
is the empty sequence, the empty sequence is returned. For
example, the signature of the constructor function corresponding to the
xs:unsignedInt
type defined in
Calling the constructor function xs:unsignedInt(12)
returns
the xs:unsignedInt
value 12. Another call of that constructor
function that returns the same xs:unsignedInt
value is
xs:unsignedInt("12")
. The same result would also be returned if the
constructor function were to be called with a node that had a typed value equal
to the xs:unsignedInt
12. The standard features described in
The semantics of the constructor function
are identical to the semantics of xs:TYPE(arg)
. See arg
cast as xs:TYPE?
If the argument to a constructor function is a literal, the result of the
function
Special rules apply to constructor functions for xs:QName
and types derived from xs:QName
and xs:NOTATION
. See
The following constructor functions for the builtin
Implementations xs:float("0.0E0")
.
But because
Implementations xs:double("0.0E0")
.
But because
See
See xs:ENTITY
and types derived from it.
Special rules apply to constructor functions for the types xs:QName
and xs:NOTATION
, for two reasons:
Values cannot belong directly to the type xs:NOTATION
, only to its subtypes.
The lexical representation of these types uses namespace prefixes, whose meaning is contextdependent.
These constraints result in the following rules:
There is no constructor function for xs:NOTATION
. Constructors are defined, however, for xs:QName
,
for types derived xs:QName
, and for types
derived xs:NOTATION
.
When converting from an xs:string
, the prefix within the lexical
xs:QName
supplied
as the argument is resolved to a namespace URI using the statically known
namespaces from the static context. If the lexical xs:QName
has no prefix, the
namespace URI of the resulting expandedQName is the default element/type
namespace from the static context. Components of the static context are
defined in
Conversion from an xs:string
to a value of type xs:QName
, a type derived from xs:QName
or a type derived from xs:NOTATION
is permitted only if the xs:string
is written as a string literal.
This applies whether the conversion is expressed using a constructor function or using the "cast as" syntax. Such a conversion can be regarded as a pseudofunction, which is always evaluated statically. It is also permitted for these constructors and casts to take a dynamicallysupplied argument in the normal manner, but as the casting table (see xs:QName
or xs:NOTATION
respectively.
When a constructor function for a namespacesensitive type is used as a literal function item
or in a partial function application (for example, fn:QName#1
or fn:QName(?)
) the namespace
bindings that are relevant are those from the static context of the literal function item or partial function application.
When a constructor function for a namespacesensitive type is obtained by means of the fn:functionlookup
function, the relevant namespace bindings are those from the static context of the call on fn:functionlookup
.
When the supplied argument to the xs:QName
constructor
function is a node, the node is atomized in the usual way, and if the result is xsl:untypedAtomic
it is then
converted as if a string had been supplied. The effect might not be what is desired.
For example, given the attribute xsi:type="my:type"
, the expression
xs:QName(@xsi:type)
might fail on the grounds that the prefix my
is undeclared. This is because the namespace bindings are taken from the static context
(that is, from the query or stylesheet), and not from the source document containing the
@xsi:type
attribute. The solution to this problem is to use the function call
resolveQName(@xsi:type, .)
instead.
Each of the three builtin list
types defined in xs:NMTOKENS
, xs:ENTITIES
, and xs:IDREFS
, has an
associated constructor function.
The function signatures are as follows:
The semantics are equivalent to casting to the corresponding types from xs:string
.
All three of these types have the facet minLength = 1
meaning that there must
always be at least one item in the list. The return type, however, allows for the fact that when the argument to
the function is an empty sequence, the result is an empty sequence.
In the case of atomic types, it is possible to use an expression such as
xs:date(@dateofbirth)
to convert an attribute value to an instance of xs:date
,
knowing that this will work both in the case where the attribute is already annotated as xs:date
,
and also in the case where it is xs:untypedAtomic
. This approach does not work with list types,
because it is not permitted to use a value of type xs:NMTOKEN*
as input to the constructor
function xs:NMTOKENS
. Instead, it is necessary to use conditional logic that performs the conversion
only in the case where the input is untyped:
if (@x instance of attribute(*, xs:untypedAtomic)) then xs:NMTOKENS(@x) else data(@x)
Special rules apply to constructor functions for namespacesensitive types, that is,
atomic types derived from xs:QName
and xs:NOTATION
, list types that have
a namespacesensitive item type, and union types that have a namespacesensitive member type. See
Consider a situation where the static context contains an hatSize
defined in a schema whose target namespace is bound
to the prefix eg
. In such a case the following constructor function is available to users:
In the case of an atomic type A, the return type of the function is A?
, reflecting
the fact that the result will be an empty sequence if the input is an empty sequence. For a union or list type,
the return type of the function is specified only as xs:anyAtomicType*
. Implementations performing
static type checking will often be able to compute a more specific result type. For example, if the target type
is a list type whose item type is the atomic type A, the result will always be an instance of A*;
if the target type is a pure union type U then the result will always be an instance of U?.
In general, however, applications needing interoperable behavior on implementations that do strict static type
checking will need to use a treat as
expression to assert the specific type of the result.
To construct an instance of apple
is derived
from xs:integer
but is not in a namespace, an instance of this type
can be constructed as follows using a cast expression (this requires that the
default element/type namespace is no namespace):
The following shows the use of the constructor function:
Constructor functions and cast expressions accept an expression and return a value
of a given type. They both convert a source value,
means exactly the same as xs:date("20030101")
."20030101"
cast as
xs:date?
The cast expression takes a type name to indicate the target type of the conversion.
See
Where the argument to a cast is a literal, the result of the function
The general rules for casting from primitive types to primitive types are defined in
xs:string
(and xs:untypedAtomic
)
follow in
When casting from xs:string
or xs:untypedAtomic
the semantics in
This section defines casting between the 19 primitive types defined in xs:untypedAtomic
,
xs:integer
and the two derived types of
xs:duration
(xs:yearMonthDuration
and xs:dayTimeDuration
). These four types are not primitive types
but they are treated as primitive types in this section. The type conversions
that are supported between primitive atomic types are indicated in the table below;
casts between other (nonprimitive) types are defined in terms of these primitives.
In this table, there is a
row for each primitive type acting as the source of the conversion and
there is a column for each primitive type acting as the target of the conversion. The
intersections of rows and columns contain one of three characters:
Y
indicates that a conversion from values of the type to which
the row applies to the type to which the column applies is supported;
N
indicates that there are no supported conversions from values
of the type to which the row applies to the type to which the column applies;
and M
indicates that a conversion from values of the type to
which the row applies to the type to which the column applies may succeed for
some values in the value space and fail for others.
xs:NOTATION
as an abstract type.
Thus, casting to xs:NOTATION
from any other type including xs:NOTATION
is not permitted and raises xs:NOTATION
to another subtype of
xs:NOTATION
is permitted.
Casting is not supported to or from xs:anySimpleType
. Thus, there is no row
or column for this type in the table below. For any node that has not been validated or
has been validated as xs:anySimpleType
, the typed value of the node is an
atomic value of type xs:untypedAtomic
. There are no atomic values with the
type annotation xs:anySimpleType
at runtime. xs:anySimpleType
is not permitted and raises
Similarly, casting is not supported to or from xs:anyAtomicType
and will raise
error xs:anyAtomicType
at runtime, although this can be a
statically inferred type.
If casting is attempted from an
In the following table, the columns and rows are identified by short codes that identify simple types as follows:
In the following table, the notation S\T
indicates that the source
(S
) of the conversion is indicated in the column below the
notation and that the target (T
) is indicated in the row to the
right of the notation.
S\T  uA  str  flt  dbl  dec  int  dur  yMD  dTD  dT  tim  dat  gYM  gYr  gMD  gDay  gMon  bool  b64  hxB  aURI  QN  NOT 

uA  Y  Y  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M 
str  Y  Y  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M 
flt  Y  Y  Y  Y  M  M  N  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N 
dbl  Y  Y  Y  Y  M  M  N  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N 
dec  Y  Y  Y  Y  Y  Y  N  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N 
int  Y  Y  Y  Y  Y  Y  N  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N 
dur  Y  Y  N  N  N  N  Y  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  N 
yMD  Y  Y  N  N  N  N  Y  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  N 
dTD  Y  Y  N  N  N  N  Y  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  N 
dT  Y  Y  N  N  N  N  N  N  N  Y  Y  Y  Y  Y  Y  Y  Y  N  N  N  N  N  N 
tim  Y  Y  N  N  N  N  N  N  N  N  Y  N  N  N  N  N  N  N  N  N  N  N  N 
dat  Y  Y  N  N  N  N  N  N  N  Y  N  Y  Y  Y  Y  Y  Y  N  N  N  N  N  N 
gYM  Y  Y  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N  N  N  N  N  N 
gYr  Y  Y  N  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N  N  N  N  N 
gMD  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N  N  N  N 
gDay  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N  N  N 
gMon  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N  N 
bool  Y  Y  Y  Y  Y  Y  N  N  N  N  N  N  N  N  N  N  N  Y  N  N  N  N  N 
b64  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  Y  Y  N  N  N 
hxB  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  Y  Y  N  N  N 
aURI  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  Y  N  N 
QN  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  Y  M 
NOT  Y  Y  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  Y  M 
Casting is permitted from any primitive type to the primitive types
xs:string
and xs:untypedAtomic
.
When a value of any simple type is cast as xs:string
, the
derivation of the xs:string
value
If xs:string
or a type derived from
xs:string
,
If xs:anyURI
, the type conversion is
performed without escaping any characters.
If xs:QName
or xs:NOTATION
:
if the qualified name
has a prefix, then
otherwise
If
If xs:integer
,
If xs:decimal
, then:
If xs:integer
, that is, if there are no
significant digits after the decimal point, then the
value is converted from an xs:decimal
to an xs:integer
and the resulting
xs:integer
is converted to an
xs:string
using the rule above.
Otherwise, the canonical lexical representation of
If xs:float
or
xs:double
, then:
xs:string
in the lexical space of xs:double
or xs:float
that when
converted to an xs:double
or xs:float
under the rules of NaN
if NaN
.
In addition,
If xs:decimal
and the
resulting xs:decimal
is converted to an
xs:string
according to the rules above, as though using an
implementation of xs:decimal
that imposes no limits on the
totalDigits
or
fractionDigits
facets.
If
If INF
" or "INF
" respectively.
In other cases, the result consists of a mantissa, which has the lexical form
of an xs:decimal
, followed by the letter "E", followed by an exponent which has
the lexical form of an xs:integer
. Leading zeroes and "+" signs are prohibited
in the exponent. For the mantissa, there must be a decimal point, and there must
be exactly one digit before the decimal point, which must be nonzero. The "+"
sign is prohibited. There must be at least one digit after the decimal point.
Apart from this mandatory digit, trailing zero digits are prohibited.
The above rules allow more than one representation of the same value.
For example, the xs:float
value whose exact decimal representation is 1.26743223E15
might be represented by any of the strings "1.26743223E15", "1.26743222E15" or
"1.26743224E15" (inter alia). It is implementationdependent which of these
representations is chosen.
If xs:dateTime
, xs:date
or xs:time
, xs:string
using the functions
described in year
component is
cast to xs:string
using eg:convertYearToString
.
The month
, day
, hour
and minute
components are cast to xs:string
using eg:convertTo2CharString
.
The second
component is cast to xs:string
using
eg:convertSecondsToString
. The timezone component, if present, is
cast to xs:string
using eg:convertTZtoString
.
Note that the hours component of the resulting string
will never be "24"
. Midnight is always represented as "00:00:00"
.
If xs:yearMonthDuration
or xs:dayTimeDuration
,
If xs:duration
then let SV
cast as xs:yearMonthDuration
, and let SV
cast as xs:dayTimeDuration
; Now, let the next intermediate value, SYM
cast as
TT
SDT
cast as
TT
If
Otherwise,
In all other cases,
To cast as xs:untypedAtomic
the value is cast as
xs:string
, as described above, and the type annotation changed
to xs:untypedAtomic
.
The string representations of numeric values are backwards compatible
with XPath 1.0 except for the special values positive and negative
infinity, negative zero and values outside the range 1.0e6
to 1.0e+6
.
When a value of any simple type is cast as xs:float
, the xs:float
If xs:float
, then
If xs:double
, then
if xs:double
value
INF
, INF
, NaN
,
positive zero, or negative zero, then xs:float
value INF
,
INF
, NaN
, positive zero, or
negative zero respectively.
otherwise, m × 2^e
where the mantissa
m
and exponent e
are signed
xs:integer
s whose value range is defined in
if m
(the mantissa of
xs:float
value (2^241 to +2^241)
, then it
is divided by 2^N
where
N
is the lowest positive
xs:integer
that brings the result
of the division within the permitted range, and
the exponent e
is increased by
N
. This is integer division (in
effect, the binary value of the mantissa is
truncated on the right). Let M
be
the mantissa and E
the exponent
after this adjustment.
if E
exceeds 104
(the
maximum exponent value in the value space of
xs:float
) then xs:float
value INF
or INF
depending on the sign of M
.
if E
is less than 149
(the minimum exponent value in the value space
of xs:float
) then xs:float
value positive or
negative zero depending on the sign of M
otherwise, xs:float
value M × 2^E
.
If xs:decimal
, or
xs:integer
, then xs:float(
cast as xs:string)
and the conversion is complete.
If xs:boolean
, 1.0E0
if true
and to 0.0E0
if false
and the conversion is complete.
If xs:untypedAtomic
or xs:string
, see
XSD 1.1 adds the value +INF
to the lexical space,
as an alternative to INF
. XSD 1.1 also adds negative zero
to the value space.
Implementations xs:float("0.0E0")
.
But because
When a value of any simple type is cast as xs:double
, the
xs:double
value
If xs:double
, then
If xs:float
or a type derived
from xs:float
, then
if xs:float
value
INF
, INF
, NaN
,
positive zero, or negative zero, then xs:double
value INF
,
INF
, NaN
, positive zero, or
negative zero respectively.
otherwise, m × 2^e
where the
mantissa m
and exponent e
are
signed xs:integer
values whose value range
is defined in xs:double
value
m × 2^e
.
If xs:decimal
or
xs:integer
, then xs:double(
cast as xs:string)
and the conversion is complete.
If xs:boolean
, 1.0E0
if true
and to 0.0E0
if false
and the conversion is complete.
If xs:untypedAtomic
or xs:string
, see
XSD 1.1 adds the value +INF
to the lexical space,
as an alternative to INF
. XSD 1.1 also adds negative zero
to the value space.
Implementations xs:double("0.0E0")
.
But because
When a value of any simple type is cast as xs:decimal
, the
xs:decimal
value
If xs:decimal
,
xs:integer
or a type derived from them, then
xs:decimal
value if need be, and the conversion is complete.
If xs:float
or
xs:double
, then xs:decimal
value, within the set of
xs:decimal
values that the implementation is
capable of representing, that is numerically closest to
xs:decimal
, (see
xs:float
or xs:double
values
NaN
, INF
, or INF
, a
If xs:boolean
, 1.0
if 1
or true
and to 0.0
if
0
or false
and the
conversion is complete.
If xs:untypedAtomic
or xs:string
, see
When a value of any simple type is cast as xs:integer
, the
xs:integer
value
If xs:integer
, or a type derived
from xs:integer
, then xs:integer
value
if need be, and the conversion is complete.
If xs:decimal
, xs:float
or
xs:double
, then xs:integer
. Thus, casting 3.1456
returns 3
and 17.89
returns
17
. Casting 3.124E1
returns 31
. If xs:float
or
xs:double
values NaN
,
INF
, or INF
, a
If xs:boolean
, 1
if 1
or true
and to 0
if 0
or false
and the conversion is complete.
If xs:untypedAtomic
or xs:string
, see
When a value of type xs:untypedAtomic
, xs:string
,
a type derived from xs:string
,
xs:yearMonthDuration
or xs:dayTimeDuration
is
cast as xs:duration
, xs:yearMonthDuration
or
xs:dayTimeDuration
,
If
If xs:duration
, or a type derived
from xs:duration
, but not
xs:dayTimeDuration
or a type derived from
xs:dayTimeDuration
, and xs:yearMonthDuration
, then
If xs:duration
, or a type derived
from duration
, but not
xs:yearMonthDuration
or a type derived from
xs:yearMonthDuration
, and xs:dayTimeDuration
, then
If xs:yearMonthDuration
or xs:dayTimeDuration
, and xs:duration
, then
If xs:yearMonthDuration
and xs:dayTimeDuration
, the cast is permitted and returns a xs:dayTimeDuration
with value 0.0 seconds.
If xs:dayTimeDuration
and xs:yearMonthDuration
, the cast is permitted and returns a xs:yearMonthDuration
with value 0 months.
If xs:untypedAtomic
or xs:string
, see
Note that casting from xs:duration
to
xs:yearMonthDuration
or xs:dayTimeDuration
loses
information. To avoid this, users can cast the xs:duration
value to both an xs:yearMonthDuration
and an
xs:dayTimeDuration
and work with both values.
In several situations, casting to date and time types requires the extraction
of a component from fn:currentdateTime
and converting it to an
xs:string
. These conversions must follow certain rules. For
example, converting an xs:integer
year value requires
converting to an xs:string
with four or more characters, preceded
by a minus sign if the value is negative.
This document defines four functions to perform these conversions. These functions are for illustrative purposes only and make no recommendations as to style or efficiency. References to these functions from the following text are not normative.
The arguments to these functions come from functions defined in this document. Thus, the functions below assume that they are correct and do no range checking on them.
Conversion from primitive types to date and time types follows the rules below.
When a value of any primitive type is cast as
xs:dateTime
, the xs:dateTime
value
If xs:dateTime
, then
If xs:date
, then let
eg:convertYearToString( fn:yearfromdate(
))
, let eg:convertTo2CharString( fn:monthfromdate(
))
, let eg:convertTo2CharString( fn:dayfromdate(
))
and let eg:convertTZtoString( fn:timezonefromdate(
))
; xs:dateTime( fn:concat(
, '',
, '',
, 'T00:00:00 '
, ) )
.
If xs:untypedAtomic
or
xs:string
, see
When a value of any primitive type is cast as xs:time
,
the xs:time
value
If xs:time
, then
If xs:dateTime
, then
xs:time( fn:concat(
eg:convertTo2CharString( fn:hoursfromdateTime(
)), ':', eg:convertTo2CharString( fn:minutesfromdateTime(
)), ':', eg:convertSecondsToString( fn:secondsfromdateTime(
)), eg:convertTZtoString( fn:timezonefromdateTime(
)) ))
.
If xs:untypedAtomic
or xs:string
, see
When a value of any primitive type is cast as xs:date
,
the xs:date
value
If xs:date
, then
If xs:dateTime
, then let
eg:convertYearToString( fn:yearfromdateTime(
))
, let eg:convertTo2CharString( fn:monthfromdateTime(
))
, let eg:convertTo2CharString( fn:dayfromdateTime(
))
and let eg:convertTZtoString(fn:timezonefromdateTime(
))
; xs:date( fn:concat(
, '',
, '',
) )
.
If xs:untypedAtomic
or xs:string
, see
When a value of any primitive type is cast as
xs:gYearMonth
, the xs:gYearMonth
value
If xs:gYearMonth
, then
If xs:dateTime
, then let
eg:convertYearToString( fn:yearfromdateTime(
))
, let eg:convertTo2CharString( fn:monthfromdateTime(
))
and let eg:convertTZtoString( fn:timezonefromdateTime(
))
; xs:gYearMonth( fn:concat(
, '',
) )
.
If xs:date
, then let
eg:convertYearToString( fn:yearfromdate(
))
, let eg:convertTo2CharString( fn:monthfromdate(
))
and let eg:convertTZtoString( fn:timezonefromdate(
))
; xs:gYearMonth( fn:concat(
, '',
) )
.
If xs:untypedAtomic
or xs:string
, see
When a value of any primitive type is cast as xs:gYear
,
the xs:gYear
value
If xs:gYear
, then
If xs:dateTime
, let
eg:convertYearToString( fn:yearfromdateTime(
))
and let eg:convertTZtoString( fn:timezonefromdateTime(
))
; xs:gYear(fn:concat(
))
.
If xs:date
, let
eg:convertYearToString( fn:yearfromdate(
))
; and let eg:convertTZtoString( fn:timezonefromdate(
))
; xs:gYear(fn:concat(
))
.
If xs:untypedAtomic
or xs:string
, see
When a value of any primitive type is cast as
xs:gMonthDay
, the xs:gMonthDay
value
If xs:gMonthDay
, then
If xs:dateTime
, then let
eg:convertTo2CharString( fn:monthfromdateTime(
))
, let eg:convertTo2CharString( fn:dayfromdateTime(
))
and let eg:convertTZtoString( fn:timezonefromdateTime(
))
; xs:gYearMonth( fn:concat(
'',
'',
) )
.
If xs:date
, then let
eg:convertTo2CharString( fn:monthfromdate(
))
, let eg:convertTo2CharString( fn:dayfromdate(
))
and let eg:convertTZtoString( fn:timezonefromdate(
))
; xs:gYearMonth( fn:concat(
'',
, '',
) )
.
If xs:untypedAtomic
or xs:string
, see
When a value of any primitive type is cast as xs:gDay
,
the xs:gDay
value
If xs:gDay
, then
If xs:dateTime
, then let
eg:convertTo2CharString( fn:dayfromdateTime(
))
and let eg:convertTZtoString( fn:timezonefromdateTime(
))
; xs:gDay(
fn:concat( ''
, ))
.
If xs:date
, then let
eg:convertTo2CharString( fn:dayfromdate(
))
and let eg:convertTZtoString( fn:timezonefromdate(
))
; xs:gDay(
fn:concat( ''
, ))
.
If xs:untypedAtomic
or xs:string
, see
When a value of any primitive type is cast as xs:gMonth
,
the xs:gMonth
value
If xs:gMonth
, then
If xs:dateTime
, then let
eg:convertTo2CharString( fn:monthfromdateTime(
))
and let eg:convertTZtoString( fn:timezonefromdateTime(
))
; xs:gMonth(
fn:concat( ''
, ))
.
If xs:date
, then let
eg:convertTo2CharString( fn:monthfromdate(
))
and let eg:convertTZtoString( fn:timezonefromdate(
))
; xs:gMonth(
fn:concat( ''
, ))
.
If xs:untypedAtomic
or xs:string
, see
When a value of any primitive type is cast as xs:boolean
, the
xs:boolean
value
If xs:boolean
, then
If xs:float
, xs:double
,
xs:decimal
or xs:integer
and
0
, +0
, 0
,
0.0
, 0.0E0
or NaN
, then
false
.
If xs:float
, xs:double
,
xs:decimal
or xs:integer
and
true
.
If xs:untypedAtomic
or xs:string
, see
Values of type xs:base64Binary
can be cast as
xs:hexBinary
and vice versa, since the two types have the same
value space. Casting to xs:base64Binary
and
xs:hexBinary
is also supported from the same type and from
xs:untypedAtomic
, xs:string
and subtypes of
xs:string
using
Casting to xs:anyURI
is supported only from the same type,
xs:untypedAtomic
or xs:string
.
When a value of any primitive type is cast as xs:anyURI
, the
xs:anyURI
value
If xs:untypedAtomic
or xs:string
see
Casting from xs:string
or xs:untypedAtomic
to
xs:QName
or xs:NOTATION
is described in
It is also possible to cast from xs:NOTATION
to xs:QName
,
or from xs:QName
to
any type derived by restriction from xs:NOTATION
. (Casting to xs:NOTATION
itself is not allowed, because xs:NOTATION
is an abstract type.) The resulting
xs:QName
or xs:NOTATION
has the same prefix, local name, and namespace URI
parts as the supplied value.
See
The
value space of ENTITY is the set of all strings that match the
NCName production ... and have been
declared as an unparsed entity in a document type definition.
However,
xs:ENTITY
match declared unparsed entities. Thus, this rule is relaxed in this specification and, in casting to xs:ENTITY
and types derived from it, no check is made that the values correspond to declared unparsed entities.
This section applies when the supplied value SV
is an instance of xs:string
or xs:untypedAtomic
,
including types derived from these by restriction. If the value is
xs:untypedAtomic
, it is treated in exactly the same way as a
string containing the same sequence of characters.
The supplied string is mapped to a typed value of the target type as defined in whiteSpace
facet for the datatype. The resulting whitespacenormalized string
must be a valid lexical form for the datatype. The semantics of casting follow the rules of
XML Schema validation. For example, "13" cast as xs:unsignedInt
returns
the xs:unsignedInt
typed
value 13
. This could also be written xs:unsignedInt("13")
.
The target type can be any simple type other than an abstract type. Specifically, it can be a type whose variety is atomic, union, or list. In each case the effect of casting to the target type is the same as constructing an element with the supplied value as its content, validating the element using the target type as the governing type, and atomizing the element to obtain its typed value.
When the target type is a derived type that is restricted by a pattern facet, the
lexical form is first checked against the pattern before further casting
is attempted (See
For example, consider a userdefined type my:boolean
which is derived by
restriction from xs:boolean
and specifies the pattern facet value="01"
.
The expression "true" cast as my:boolean
would fail with a
Facets other than pattern
are checked my:height
defined as a restriction of xs:integer
with the facet <maxInclusive value="84"/>
,
then the expression "100" cast as my:height
would fail with a
Casting to the types xs:NOTATION
, xs:anySimpleType
,
or xs:anyAtomicType
is not permitted because these types are abstract (they have
no immediate instances).
Special rules apply when casting to namespacesensitive types. The types xs:QName
and xs:NOTATION
are namespacesensitive. Any type derived by restriction from
a namespacesensitive type is itself namespacesensitive, as is any union type having a
namespacesensitive type among its members, and any list type having a namespacesensitive type
as its item type. For details, see
This version of the specification allows casting between xs:QName
and xs:NOTATION
in either direction; this was not permitted in the previous Recommendation. This version also removes
the rule that only a string literal (rather than a dynamic string) may be cast to an xs:QName
When casting to a numeric type:
If the value is too large or too small to be accurately represented by the implementation,
it is handled as an overflow or underflow as defined in
If the target type is xs:float
or xs:double
, the string 0
(and equivalents
such as 0.0
or 000
)
In casting to xs:decimal
or to a type derived from xs:decimal
,
if the value is not too large or too small but nevertheless cannot be represented accurately
with the number of decimal digits available to the implementation, the implementation may round
to the nearest representable value or may raise a dynamic error
In casting to xs:date
, xs:dateTime
, xs:gYear
,
or xs:gYearMonth
(or types derived from these), if the value is too large or too
small to be represented by the implementation, a
In casting to a duration value, if the value is too large or too small to be represented by the
implementation, a