This document defines constructor functions, operators and functions on the datatypes defined in
This is a
This document has been jointly produced by the
This draft includes corrections and changes based on
Comments on this document should be made in W3C's
The XML Query and XSL WGs plan to submit this specification for consideration as a
The
The patent policy for this document is the
The purpose of this document is to catalog the functions and operators required for
XPath 2.0, XML Query 1.0 and XSLT 2.0. The exact syntax used to invoke these
functions and operators is specified in
This document defines constructor functions and functions that take typed values as
arguments. Some of the functions define the semantics of operators discussed in
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:
Support for XML 1.0 and XML 1.1 by the datatypes used in Functions and Operators.
It is
The functions and operators discussed in this document are contained in one of
four namespaces (see xs:QName
. Constructor functions for the builtin datatypes defined
in http://www.w3.org/2001/XMLSchema
,
and named in this document using the xs
prefix. The namespace
prefix used in this document for functions that are available to users is
fn
. Operator functions are named with the prefix op
.
The datatypes defined in xdt
.
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 prefix used for the functions, datatypes and errors can vary, as long as the prefix is bound to the correct URI.
The URIs of the namespaces and the default prefixes associated with them are:
http://www.w3.org/2001/XMLSchema
for constructors 
associated with xs
.
http://www.w3.org/2005/xpathfunctions
for functions  associated with fn
.
http://www.w3.org/2005/xpathdatatypes
for the datatypes  associated with xdt
.
http://www.w3.org/2005/xqterrors
 associated with
err
.
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.
The functions defined with an fn
prefix are callable by the user.
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
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
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 xdt: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, referred to as ().
Some functions accept a sequence of zero or more values as an argument. This is
indicated by following the name of 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.
This document uses the phrase "namespace URI" to identify the concept identified
in
It also uses the term expandedQName
defined below.
An expandedQName is a pair of values consisting of a namespace URI
and a local name. They belong to the value space of the 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 diagram below shows the types for which functions are defined in this
document. These include the builtin types defined by xs:IDREFS
, xs:NMTOKENS
,
xs:ENTITIES
and userdefined list and union types
are
special types in that these types are lists or unions rather than true subtypes.
Dashed lines connect a union type above with its component types below.
The information in the above diagram is reproduced below in tabular form. For
ease of presentation the information is divided into three tables. The first
table shows the top three layers of the hierarchy starting at
xs:anyType
. The second table shows the types derived from
xdt:anyAtomicType
. The third table shows the types defined in
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  
xdt:untyped  
xs:anySimpleType  
userdefined list and union types  
xs:IDREFS  
xs:NMTOKENS  
xs:ENTITIES  
xdt:anyAtomicType 
The table below shows the datatypes derived from xdt:anyAtomicType
.
This includes all the
Each type whose name is indented is derived from the type whose name appears nearest above it with one less level of indentation.
xdt:untypedAtomic  
xs:dateTime  
xs:date  
xs:time  
xs:duration  
xdt:yearMonthDuration  
xdt: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 
The table below shows the type hierarchy for the types introduced in
item  
xdt:anyAtomicType  
node  
attribute  
userdefined attribute types  
comment  
document  
userdefined document types  
element  
userdefined element types  
processinginstruction  
text 
The terminology used to describe the functions and operators on
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.
The scope over which any two calls on a function would be executed. In XSLT, it applies to any two calls on the function executed during the same transformation. In XQuery, it applies to any two calls executed during the evaluation of a toplevel expression i.e. an expression not contained in any other expression. In other contexts, the scope is specified by the host environment that invokes the function library.
Most of the functions in the core library have the property that
calling the same function twice within an fn:doc()
, fn:collection()
,
fn:currentdateTime()
, fn:currentdate
and
fn:currenttime()
whose result depends on the external
environment. Where the function returns nodes, stability means that
the returned nodes are identical, not merely equal and are returned
in the same order.. Some other functions, for example fn:position()
and fn:last(), depend on the dynamic context and may, therefore,
produce different results each time they are called. These functions
are said to be contextual.
Some other functions, for example fn:position()
and
fn:last()
, depend on the dynamic context and may,
therefore, produce different results each time they are called.
These functions are said to be
Within this specification, the term "URI" refers to Universal Resource Identifiers as
defined in xs:anyURI
datatype as defined in xs:anyURI
is a wider definition than the definition in
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

Summary: Returns an expandedQName for node kinds that can have names. For other
kinds of nodes it returns the empty sequence. If $arg
is the empty
sequence, the empty sequence is returned.
Summary: Returns an xs:boolean
indicating whether the argument node
is nilled
. If the argument is not an element node, returns the
empty sequence. If the argument is the empty sequence, returns the empty sequence.
Summary: Returns the value of $arg
represented as a
xs:string
. If no argument is supplied, this function returns the
string value of the context item (.
).
If no argument is supplied and the context item is undefined, an error is raised:
If $arg
is the empty sequence, the zerolength string is returned.
If $arg
is a node, the function returns the stringvalue of the
node, as obtained using the dm:stringvalue
accessor defined in the
If $arg
is an atomic value, then the function returns the same
string as is returned by the expression
(see $arg
cast as xs:string
Summary: fn:data
takes a sequence of items and returns a sequence of
atomic values.
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 returned.
If the item is a node:
If the node does not have a typed value an error is
raised
Otherwise, fn:data()
returns the typed value of the
node as defined by the accessor function
dm:typedvalue
in
Summary: Returns the value of the baseuri property for $arg
as
defined by the accessor function dm:baseuri()
for that kind of
node in $arg
is not
specified, returns the value of the baseuri property of the context item
(.
) with the above semantics. If the context item is not a node, an
error is raised:
If $arg
is the empty sequence, the empty sequence is returned.
Document, element and processinginstruction nodes have a baseuri property which
may be empty. The baseuri property of all other node types is the empty
sequence. The value of the baseuri property is returned if it exists and is not
empty. Otherwise, if the node has a parent, the value of
dm:baseuri()
applied to its parent is returned, recursively. If
the node does not have a parent, or if the recursive ascent up the ancestor
chain encounters a node whose baseuri property is empty and it does not have a
parent, the empty sequence is returned.
See also fn:staticbaseuri
.
Summary: Returns the value of the documenturi property for $arg
as
defined by the dm:documenturi
accessor function defined in
If $arg
is the empty sequence, the empty sequence is returned.
Returns the empty sequence if the node is not a document node. Otherwise, returns
the value of the dm:documenturi
accessor of the document node.
If fn:documenturi($arg)
does not return the empty sequence, then
the following expression always holds:
In this document, as well as in an error is raised
is used. Raising an error is equivalent to invoking 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 invocation. Invocation of 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 invoked as above
but may also be invoked from xs:QName
argument.
Summary: The fn:error
function raises an error. While this function never returns a value, an
error is returned to the external processing environment as an
xs:anyURI
or an xs:QName
. The error xs:anyURI
is derived from the error xs:QName
. An error xs:QName
with
namespace URI NS and local part LP will be returned as the xs:anyURI
NS#LP. The method by which the xs:anyURI
or xs:QName
is
returned to the external processing environment is
If an invocation provides $description
and $errorobject
,
then these values may also be returned to the external processing environment. The
method by which these values are provided to the external environment is
The value of the $description
parameter may need to be localized.
Note that none
is a special type defined in
If fn:error
is invoked with no arguments, then its behavior is the same
as the invocation of the following expression:
If the first argument in the third or fourth signature is the empty sequence it is
assumed to be the xs:QName
constructed by:
fn:error()
returns
http://www.w3.org/2005/xqterrors#FOER0000
to the
external processing environment.
fn:error(fn:QName('http://www.example.com/HR', 'myerr:toohighsal'),
'Does not apply because salary is too high')
returns
http://www.example.com/HR#toohighsal
and the xs:string
"Does not apply because salary is too high"
to the external
processing environment.
This function is intended to be used in debugging queries by providing a trace of their execution.
The input $value
is returned, unchanged, as the result of the function.
In addition, the inputs $value
, converted to an xs:string
,
and $label
may be directed to a trace data set. The destination of the
trace output is 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.
Every builtin atomic type that is defined in xs:NOTATION
, has an
associated constructor function; as do xdt:untypedAtomic
, defined
in xdt:yearMonthDuration
and xdt:dayTimeDuration
defined
in 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 a type
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
Invoking the constructor function xs:unsignedInt(12)
returns
the xs:unsignedInt
value 12. Another invocation 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 invoked 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)
, except for constructors for arg
cast as xs:TYPE?
xs:QName
and types derived from
xs:NOTATION
which are identical to cast as
. See xs:TYPE
If the argument to a constructor function is a literal, the result of the function may be evaluated statically; if an error is found during such evaluation, it may be reported as a static error.
Constructor functions for xs:QName
and
types derived from xs:QName
and xs:NOTATION
, are constrained to take a xs:string
literal as
their argument. (This means that they are actually pseudofunctions: they can
always be evaluated statically). A
static error is raised xs:QName
or a type derived from xs:QName
or xs:NOTATION
is not an xs:string
literal.
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 discussed in
The following constructor functions for the builtin types are supported:
Implementations xs:float("0.0E0")
.
Implementations xs:double("0.0E0").
$arg
must be a xs:string
literal.
See xs:ENTITY
and types derived from it.
A special constructor function is provided for constructing a
xs:dateTime
value from a xs:date
value and a
xs:time
value.
The result xs:dateTime
has a date component whose value is equal to
$arg1
and a time component whose value 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.
If the two arguments have different timezones, an error is
raised:
fn:dateTime(xs:date("19991231"), xs:time("12:00:00"))
returns xs:dateTime("19991231T12:00:00").
fn:dateTime(xs:date("19991231"), xs:time("24:00:00"))
returns
xs:dateTime("19991231T00:00:00")
because "24:00:00"
is an alternate lexical form for "00:00:00".
For every atomic type in the static context (See
Consider a situation where the static context contains a type
called hatSize
defined in a schema whose target namespace is bound
to the prefix my
. In such a case the constructor function:
is available to users.
To construct an instance of an atomic type that is not in a namespace, it is
necessary to use a cast expression or undeclare the default function namespace. For example, if the userdefined type 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:
This section discusses 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.
This differs from NaN
as being equal to itself and defines only a single zero in the value space while NaN
as unequal to all other values including itself and can produce distinct results of positive zero and negative zero. (These are two different machine representations for the same
The following functions define the semantics of 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
.
On overflow and underflow situations during arithmetic operations conforming
implementations
For xs:float
and xs:double
operations, overflow
behavior
Raising an error
Returning INF
or INF
.
Returning the largest (positive or negative) noninfinite number.
For xs:float
and xs:double
operations,
underflow behavior
Raising an error
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
Summary: Backs up the "+" operator and returns the arithmetic sum of its
operands: ($arg1 + $arg2
).
For xs:float
or xs:double
values, if one of
the operands is a zero or a finite number and the other
is INF
or INF
, INF
or
INF
is returned. If both operands are INF
,
INF
is returned. If both operands are INF
,
INF
is returned. If one of the operands is
INF
and the other is INF
, NaN
is returned.
Summary: Backs up the "" operator and returns the arithmetic difference of
its operands: ($arg1  $arg2
).
For xs:float
or xs:double
values, if one of
the operands is a zero or a finite number and the other
is INF
or INF
, an infinity of the appropriate
sign is returned. If both operands are INF
or
INF
, NaN
is returned. If one of the operands
is INF
and the other is INF
, an infinity of
the appropriate sign is returned.
Summary: Backs up the "*" operator and returns the arithmetic product of its
operands: ($arg1 * $arg2
).
For xs:float
or xs:double
values, if one of
the operands is a zero and the other is an infinity, NaN
is
returned. If one of the operands is a nonzero number and the other
is an infinity, an infinity with the appropriate sign is returned.
Summary: Backs up the "div" operator and returns the arithmetic quotient of
its operands: ($arg1 div $arg2
).
As a special case, if the types of both $arg1
and
$arg2
are xs:integer
, then the return type is xs:decimal
.
For xs:decimal
and xs:integer
operands, if the
divisor is (positive or negative) zero, an error is raised xs:float
and xs:double
operands, floating point
division is performed as specified in
For xs:float
or xs:double
values, a positive
number divided by positive zero returns 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
.
Summary: This function backs up the "idiv" operator and performs an integer division: that is, it divides the first argument by the second, and returns the integer obtained by truncating the fractional part of the result. The division is performed so that the sign of the fractional part is the same as the sign of the dividend.
If the dividend, $arg1
, is not evenly divided by the divisor,
$arg2
, then the quotient is the xs:integer
value
obtained, ignoring (truncating) any remainder that results from the division
(that is, no rounding is performed). Thus, the semantics
are equivalent to $a idiv $b
except for error situations.($a div $b) cast as xs:integer
If the divisor is (positive or negative) zero, then an error is raised NaN
or if $arg1
is INF
or INF
then
an error is raised
The semantics of this function are different from integer division as defined in programming languages such as Java and C++.
op:numericintegerdivide(10,3)
returns 3
op:numericintegerdivide(3,2)
returns 1
op:numericintegerdivide(3,2)
returns 1
op:numericintegerdivide(3,2)
returns 1
op:numericintegerdivide(9.0,3)
returns 3
op:numericintegerdivide(3.5,3)
returns 1
op:numericintegerdivide(3.0,4)
returns 0
op:numericintegerdivide(3.1E1,6)
returns 5
op:numericintegerdivide(3.1E1,7)
returns 4
Summary: Backs up the "mod" operator. Informally, this function returns the
remainder resulting from dividing $arg1
, the dividend, by
$arg2
, the divisor. 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:integer
and xs:decimal
operands, if
$arg2
is zero, then an error is raised
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
op:numericmod(10,3)
returns 1
.
op:numericmod(6,2)
returns 0
.
op:numericmod(4.5,1.2)
returns 0.9
.
op:numericmod(1.23E2, 0.6E1)
returns 3.0E0
.
Summary: Backs up the unary "+" operator and returns its operand with the
sign unchanged: (+ $arg
). Semantically, this operation performs
no operation.
Summary: Backs up the unary "" operator and returns its operand with the
sign reversed: ( $arg
). If $arg
is positive, its
negative is returned; if it is negative, its positive is returned.
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.
Operator  Meaning 

op:numericequal

Equality comparison 
op:numericlessthan

Lessthan comparison 
op:numericgreaterthan

Greaterthan comparison 
Summary: Returns true if and only if the value of $arg1
is equal
to the value of $arg2
. 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.
This function backs up the "eq", "ne", "le" and "ge" operators on numeric values.
Summary: Returns true
if and only if $arg1
is less
than $arg2
. 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
.
This function backs up the "lt" and "le" operators on numeric values.
Summary: Returns true
if and only if $arg1
is
greater than $arg2
. 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
.
This function backs up the "gt" and "ge" operators on numeric values.
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 the argument. 
fn:ceiling

Returns the smallest number with no fractional part that is greater than or equal to the argument. 
fn:floor

Returns the largest number with no fractional part that is less than or equal to the argument. 
fn:round

Rounds to the nearest number with no fractional part. 
fn:roundhalftoeven

Takes a number and a precision and returns a number rounded to the given precision. If the fractional part is exactly half, the result is the number whose least significant digit is even. 
Summary: Returns the absolute value of $arg
. If
$arg
is negative returns $arg
otherwise returns
$arg
. If 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
fn:abs(10.5)
returns 10.5
.
fn:abs(10.5)
returns 10.5
.
Summary: Returns the smallest (closest to negative infinity) number with no
fractional part that is not less than the value of $arg
. If
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
fn:ceiling(10.5)
returns 11
.
fn:ceiling(10.5)
returns 10
.
Summary: Returns the largest (closest to positive infinity) number with no
fractional part that is not greater than the value of $arg
. If
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 float
and 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
fn:floor(10.5)
returns 10
.
fn:floor(10.5)
returns 11
.
Summary: Returns the number with no fractional part that is closest to the
argument. If there are two such numbers, then the one that is closest to
positive infinity is returned. If 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 infinity, then positive infinity is returned. If the
argument is negative infinity, then negative infinity is returned. 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, but greater than or equal to 0.5, then
negative zero is returned. In the cases where positive zero or negative zero is returned, negative zero or positive zero may be returned as
For the last two cases, note that the result is not the same as fn:floor(x+0.5)
.
For detailed type semantics, see
fn:round(2.5)
returns 3.
fn:round(2.4999)
returns 2
.
fn:round(2.5)
returns 2
(not the
possible alternative, 3
).
Summary: The value returned is the nearest (that is, numerically closest)
numeric 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...), returns the one
whose least significant digit is even. If 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 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, but greater than or equal to 0.5, then
negative zero is returned.
If $arg
is of type xs:float
or xs:double
, rounding occurs on the value of the mantissa
computed with exponent = 0.
For detailed type semantics, see
fn:roundhalftoeven(0.5)
returns 0
.
fn:roundhalftoeven(1.5)
returns 2
.
fn:roundhalftoeven(2.5)
returns 2
.
fn:roundhalftoeven(3.567812E+3, 2)
returns 3567.81E0
.
fn:roundhalftoeven(4.7564E3, 2)
returns
0.0E0
.
fn:roundhalftoeven(35612.25, 2)
returns
35600
.
This section discusses 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.
It is
Unless explicitly stated, the xs:string
values returned by the
functions in this document are not normalized in the sense of
This document uses the term "code point", sometimes spelt "codepoint" (also known as "character number" or "code position") to mean a nonnegative integer that represents a character in some encoding. See
In functions that involve character counting such
as fn:substring
, fn:stringlength
and
fn:translate
, what is counted is the number of XML characters
in the string (or equivalently, the number of Unicode code points). Some
implementations may represent a code point above xFFFF using two 16bit
values known as a surrogate. A surrogate counts as one character, not two.
Function  Meaning 

fn:codepointstostring

Creates an xs:string from a sequence of Unicode code points. 
fn:stringtocodepoints

Returns the sequence of Unicode code points that constitute an
xs:string . 
Summary: Creates an xs:string
from a sequence of $arg
is the empty sequence. If any of the
code points in $arg
is not a legal XML character, an error is
raised
fn:codepointstostring((2309, 2358, 2378, 2325))
returns "अशॊक"
Summary: Returns the sequence of xs:string
. If $arg
is a zerolength string or the
empty sequence, the empty sequence is returned.
fn:stringtocodepoints("Thérèse")
returns the sequence (84, 104, 233, 114, 232, 115, 101)
A collation is a specification of the manner in which character strings are
compared and, by extension, ordered. When values whose type is
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 code point values). The
Collations can indicate that two different code points are, in fact, equal for comparison purposes (e.g., "v" and "w" are considered equivalent in Swedish). Strings can be compared codepointbycodepoint or in a linguistically appropriate manner, as defined by the collation.
Some collations, especially those based on the http://www.w3.org/2005/xpathfunctions/collation/codepoint
,
provides the ability to compare strings based on code point values. Every
implementation of XQuery/XPath must support the collation based on code
point values.
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,
it is assumed to be relative to the value of the baseuri property in the
static context. This specification also defines the manner in which a
default collation is determined if the collation argument is not specified
in invocations of functions that use a collation but allow it to be omitted.
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 http://www.w3.org/2005/xpathfunctions/collation/codepoint
).
The decision of which collation to use for a given comparison or ordering function is determined by the following algorithm:
If the function specifies an explicit collation, CollationA (e.g., if
the optional collation argument is specified in an invocation of the
fn:compare()
function), then:
If CollationA is supported by the implementation, then CollationA is used.
Otherwise, an error is raised
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, an error is raised
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.
Function  Meaning  

fn:compare

Returns 1, 0, or 1, depending on whether the value of the first argument is respectively less than, equal to, or greater than the value of the second argument, according to the rules of the collation that is used.  
fn:codepointequal

Returns true if the two arguments are equal using
the Unicode code point collation. 
Summary: 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 the invocation of this function is determined according
to the rules in
If either argument is the empty sequence, the result is the empty sequence.
This function, invoked with the first signature, backs up the "eq", "ne", "gt", "lt", "le" and "ge" operators on string values.
fn:compare('abc', 'abc')
returns 0.
fn:compare('Strasse', 'Straße')
returns 0
if and only if the default collation includes provisions that
equate ss
and the (German) character
ß
(sharps
). (Otherwise,
the returned value depends on the semantics of the default collation.)
fn:compare('Strasse', 'Straße', 'deutsch')
returns 0 if the collation identified by the relative URI
constructed from the string
value
deutsch
includes provisions that equate
ss
and the (German) character
ß
(sharps
). (Otherwise,
the returned value depends on the semantics of that collation.)
fn:compare('Strassen', 'Straße')
returns 1
if the default collation includes provisions that treat
differences between ss
and the (German) character
ß
(sharps
) with less
strength than the differences between the base characters, such
as the final n
.
Summary: Returns true
or false
depending on whether
the value of $comparand1
is equal to the value of
$comparand2
, according to the Unicode code point collation (http://www.w3.org/2005/xpathfunctions/collation/codepoint
).
If either argument is the empty sequence, the result is the empty sequence.
This function allows xs:anyURI
values to be compared without having to specify the Unicode code point collation.
The following functions are defined on values of type xs:string
and
types derived from it.
Function  Meaning 

fn:concat

Concatenates two or more xdt:anyAtomicType arguments
cast to xs:string . 
fn:stringjoin

Returns the xs:string produced by concatenating a
sequence of xs:string s using an optional separator. 
fn:substring

Returns the xs:string located at a specified place
within an argument xs:string . 
fn:stringlength

Returns the length of the argument. 
fn:normalizespace

Returns the whitespacenormalized value of the argument. 
fn:normalizeunicode

Returns the normalized value of the first argument in the normalization form specified by the second argument. 
fn:uppercase

Returns the uppercased value of the argument. 
fn:lowercase

Returns the lowercased value of the argument. 
fn:translate

Returns the first xs:string argument with occurrences
of characters contained in the second argument replaced by the
character at the corresponding position in the third argument. 
fn:encodeforuri

Returns the xs:string argument with certain characters escaped to enable the resulting string to be used as a path segment in a URI. 
fn:iritouri

Returns the xs:string argument with certain characters escaped to enable the resulting string to be used as (part of) a URI. 
fn:escapehtmluri

Returns the xs:string argument with certain characters escaped in the manner that html user agents handle attribute values that expect URIs. 
When the above operators and functions are applied to datatypes derived from
xs:string
, they are guaranteed to return legal
xs:string
s, but they might not return a legal value for the
particular subtype 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
.
Summary: Accepts two or more xdt:anyAtomicType
arguments and
casts them to xs:string
. Returns the xs:string
that is the concatenation of the values of its arguments after conversion.
If any of the arguments is the empty sequence, the argument is treated as
the zerolength string.
The fn:concat
function is specified to allow an two or more
arguments that 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 the note above, the result of fn:concat
may not be normalized. 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.
fn:concat('un', 'grateful')
returns
. ungrateful
fn:concat('Thy ', (), 'old ', "groans", "", ' ring', '
yet', ' in', ' my', ' ancient',' ears.')
returns
. Thy old groans ring yet in my ancient ears.
fn:concat('Ciao!',())
returns
. Ciao!
fn:concat('Ingratitude, ', 'thou ', 'marblehearted', '
fiend!')
returns
. Ingratitude, thou marblehearted fiend!
Summary: Returns a xs:string
created by concatenating the
members of the $arg1
sequence using $arg2
as a
separator. 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 zerolength
string is returned.
fn:stringjoin(('Now', 'is', 'the', 'time', '...'), '
')
returns
. Now is the time ...
fn:stringjoin(('Blow, ', 'blow, ', 'thou ', 'winter ',
'wind!'), '')
returns
. Blow, blow, thou winter wind!
fn:stringjoin((), 'separator')
returns .
Assume a document:
with the <section>
as the context node,
the
fn:stringjoin(for $n in ancestororself::* return
name($n), '/')
returns
doc/chap/section
Summary: Returns the portion of the value of $sourceString
beginning at the position indicated by the value of
$startingLoc
and continuing for the number of characters
indicated by the value of $length
. The characters returned do
not extend beyond $sourceString
. If $startingLoc
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 $p
obeys:
fn:round($startingLoc) <= $p < fn:round($startingLoc) + fn:round($length)
The two argument version of the function assumes that $length
is
infinite and returns the characters in $sourceString
whose
position $p
obeys:
fn:round($startingLoc) <= $p < fn:round(INF)
In the above computations, the rules for op:numericlessthan()
and op:numericgreaterthan()
apply.
If the value of $sourceString
is the empty sequence, the
zerolength string is returned.
The first character of a string is located at position 1, not position 0.
fn:substring("motor car", 6)
returns " car"
.
Characters starting at position 6 to the end of
$sourceString
are selected.
fn:substring("metadata", 4, 3)
returns "ada"
.
Characters at positions greater than or equal to 4 and less than 7 are selected.
fn:substring("12345", 1.5, 2.6)
returns "234"
.
Characters at positions greater than or equal to 2 and less than 5 are selected.
fn:substring("12345", 0, 3)
returns "12"
.
Characters at positions greater than or equal to 0 and less than 3 are selected. Since the first position is 1, these are the characters at positions 1 and 2.
fn:substring("12345", 5, 3)
returns ""
.
Characters at positions greater than or equal to 5 and less than 2 are selected.
fn:substring("12345", 3, 5)
returns "1"
.
Characters at positions greater than or equal to 3 and less than 2 are selected. Since the first position is 1, this is the character at position 1.
fn:substring("12345", 0 div 0E0, 3)
returns ""
.
Since 0 div 0E0
returns NaN
, and
NaN
compared to any other number returns
false
, no characters are selected.
fn:substring("12345", 1, 0 div 0E0)
returns ""
.
As above.
fn:substring((), 1, 3)
returns ""
.
fn:substring("12345", 42, 1 div 0E0)
returns "12345"
.
Characters at positions greater than or equal to 42 and less than INF are selected.
fn:substring("12345", 1 div 0E0, 1 div 0E0)
returns ""
.
Since INF + INF
returns NaN
, no
characters are selected.
Summary: Returns an xs:integer
equal to the length in characters
of the value of $arg
.
If the value of $arg
is the empty sequence, the
xs:integer
0 is returned.
If no argument is supplied, $arg
defaults to the string value
(calculated using fn:string()
) of the context item
(.
). If no argument is supplied and the context item is
undefined an error is raised:
fn:stringlength("Harp not on that string, madam; that is
past.")
returns 45
.
fn:stringlength(())
returns 0
.
Summary: Returns the value of $arg
with whitespace normalized by
stripping leading and trailing whitespace and replacing sequences of one or
more than one whitespace character with a single space, #x20
.
The whitespace characters are defined in the metasymbol S (Production 3)
of
The definition of the metasymbol S (Production 3), is unchanged
in
If the value of
$arg
is the empty sequence, returns the zerolength string.
If no argument is supplied, $arg
defaults to the string value
(calculated using fn:string()
) of the context item
(.
). If no argument is supplied and the context item is
undefined an error is raised:
fn:normalizespace(" The wealthy curled darlings
of our nation. ")
returns
. The wealthy curled darlings of our nation.
fn:normalizespace(())
returns .
Summary: Returns the value of $arg
normalized according to the
normalization criteria for a normalization form identified by the value of
$normalizationForm
. The effective value of the
$normalizationForm
is computed by removing leading and trailing
blanks, if present, and converting to upper case.
If the value of $arg
is the empty sequence, returns the
zerolength string.
See
If the $normalizationForm
is absent, as in the first format
above, it shall be assumed to be "NFC"
If the effective value of $normalizationForm
is
NFC
, then the value returned by the function is the
value of $arg
in Unicode Normalization Form C (NFC).
If the effective value of $normalizationForm
is
NFD
, then the value returned by the function is the
value of $arg
in Unicode Normalization Form D (NFD).
If the effective value of $normalizationForm
is
NFKC
, then the value returned by the function is the
value of $arg
in Unicode Normalization Form KC (NFKC).
If the effective value of $normalizationForm
is
NFKD
, then the value returned by the function is the
value of $arg
in Unicode Normalization Form KD (NFKD).
If the effective value of $normalizationForm
is
FULLYNORMALIZED
, then the value returned by the
function is the value of $arg
in the fully normalized form.
If the effective value of $normalizationForm
is the
zerolength string, no normalization is performed and
$arg
is returned.
Conforming implementations $normalizationForm
is other than
one of the values supported by the implementation, then an error is raised
Summary: Returns the value of $arg
after translating every
character to its uppercase correspondent as defined in the Unicode standard
If the value of $arg
is the empty sequence, the zerolength
string is returned.
Case mappings may change the length of a string. In general, the two
functions are not inverses of each other
fn:lowercase(fn:uppercase($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.
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.
Results may violate 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.
fn:uppercase("abCd0")
returns
"ABCD0"
.
Summary: returns the value of $arg
after translating every
character to its lowercase correspondent as defined in the Unicode standard
If the value of $arg
is the empty sequence, the zerolength
string is returned.
Case mappings may change the length of a string. In general, the two
functions are not inverses of each other
fn:lowercase(fn:uppercase($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.
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.
Results may violate 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.
fn:lowercase("ABc!D")
returns
"abc!d"
.
Summary: Returns the value of $arg
modified so that every
character in the value of $arg
that occurs at some position
$mapString
has been replaced by
the character that occurs at position $transString
.
If the value of $arg
is the empty sequence, the zerolength
string is returned.
Every character in the value of $arg
that does not appear in the
value of $mapString
is unchanged.
Every character in the value of $arg
that appears at some
position $mapString
, where the
value of $transString
is less than $mapString
is
the zerolength string $arg
is returned.
If a character occurs more than once in $mapString
, then the
first occurrence determines the replacement character. If
$transString
is longer than $mapString
, the excess
characters are ignored.
fn:translate("bar","abc","ABC")
returns "BAr"
fn:translate("aaa","abc","ABC")
returns "AAA"
.
fn:translate("abcdabc", "abc", "AB")
returns
"ABdAB"
.
Summary: This function should be used to process an xs:string
to be used as a path segment in a URI. It is invertible but not idempotent. This function applies the URI escaping rules defined in section 2 of
$uripart
. The effect of the
function is to escape a set of identified characters in the string. Each
such character is replaced in the string 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.
If $uripart
is the empty sequence, returns the zerolength string.
All characters are escaped other than the lower case letters az, the upper case letters AZ, the digits 09, the NUMBER SIGN "#" and HYPHENMINUS (""), LOW LINE ("_"), FULL STOP ".", EXCLAMATION MARK "!", TILDE "~", ASTERISK "*", APOSTROPHE "'", LEFT PARENTHESIS "(", and RIGHT PARENTHESIS ")".
Since
fn:encodeforuri
("http://www.example.com/00/Weather/CA/Los%20Angeles#ocean")
returns "http%3A%2F%2Fwww.example.com%2F00%2FWeather%2FCA%2FLos%2520Angeles#ocean"
. This is probably not what the user wants as the '%' sign in the percentencoded space character is escaped.
concat("http://www.example.com/", encodeforuri("~bébé")) returns "http://www.example.com/~b%C3%A9b%C3%A9"
.
concat("http://www.example.com/", encodeforuri("100% organic")) returns "http://www.example.com/100%25%20organic"
.
Summary: This function should be used to process an xs:string
to be used as a URI or part of a URI. It is idempotent but not invertible. This function applies the URI escaping rules defined in section 2 of
$uripart
, which typically
represents all or part of a URI. The effect of the
function is to escape a set of identified characters in the string. Each
such character is replaced in the string 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.
If $uripart
is the empty sequence, returns the zerolength string.
All characters are escaped other than the lower case letters az, the upper case letters AZ, the digits 09, the NUMBER SIGN "#" and HYPHENMINUS (""), LOW LINE ("_"), FULL STOP ".", EXCLAMATION MARK "!", TILDE "~", ASTERISK "*", APOSTROPHE "'", LEFT PARENTHESIS "(", and RIGHT PARENTHESIS ")", SEMICOLON ";", SOLIDUS "/", QUESTION MARK "?", COLON ":", COMMERCIAL AT "@", AMPERSAND "&", EQUALS SIGN "=", PLUS SIGN "+", DOLLAR SIGN "$", COMMA ",", LEFT SQUARE BRACKET "[", RIGHT SQUARE BRACKET "]", and the PERCENT SIGN "%".
Since
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".
fn:iritouri
("http://www.example.com/00/Weather/CA/Los%20Angeles#ocean")
returns "http://www.example.com/00/Weather/CA/Los%20Angeles#ocean"
.
fn:iritouri
("http://www.example.com/~bébé")
returns "http://www.example.com/~b%C3%A9b%C3%A9"
.
Summary: This function escapes all characters except printable characters of the USASCII coded character set, specifically the octets ranging from 32 to 126 (decimal). The effect of the function is to escape a URI in the manner html user agents handle attribute values that expect URIs. Each character in $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.
If $uri
is the empty sequence, returns the zerolength string.
The behavior of this function corresponds to the recommended handling
of nonASCII characters in URI attribute values as described in
fn:escapehtmluri
("http://www.example.com/00/Weather/CA/Los Angeles#ocean")
returns "http://www.example.com/00/Weather/CA/Los Angeles#ocean"
.
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');"
.
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 characters in $arg1
which $arg2
matches.
When the Unicode code point collation
is used, this simply involves determining whether $arg1
contains a
contiguous sequence of characters whose code points are the same, one for one,
with the code points of the characters in $arg2
.
When a collation is specified, the rules are more complex.
All collations support the capability of deciding whether two strings are
considered equal, and if not, which of the strings should be regarded as
preceding the other. For functions such as 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.
In the definitions below, we say that $arg1
contains
$arg2
at positions m
through n
if the
collation units corresponding to characters in positions m
to
n
of $arg1
are the same as the collation units
corresponding to all the characters of $arg2
modulo ignorable
collation units. In the simple case of the Unicode code point collation, the
collation units are the same as the characters of the string. See
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

Indicates whether one xs:string contains another
xs:string . A collation may be specified. 
fn:startswith

Indicates whether the value of one xs:string begins
with the collation units of another xs:string . A
collation may be specified. 
fn:endswith

Indicates whether the value of one xs:string ends with
the collation units of another xs:string . A collation
may be specified. 
fn:substringbefore

Returns the collation units of one xs:string that
precede in that xs:string the collation units of
another xs:string . A collation may be specified. 
fn:substringafter

Returns the collation units of xs:string that follow in
that xs:string the collation units of another
xs:string . A collation may be specified. 
Summary: 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
minimal match to the collation units in the value of $arg2
,
according to the collation that is used.
"Minimal match" is defined in
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 the invocation of this function is determined according
to the rules in
CollationA used in these examples is a collation in which both "" and "*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation
element" in
fn:contains ( "tattoo", "t")
returns true
.
fn:contains ( "tattoo", "ttt")
returns false
.
fn:contains ( "", ())
returns true
. The first rule is applied, followed by the second rule.
fn:contains ( "abcdefghi", "def", "CollationA")
returns true
.
fn:contains ( "a*b*c*d*e*f*g*h*i*", "def",
"CollationA")
returns true
.
fn:contains ( "abcd***ef**ghi", "def",
"CollationA")
returns true
.
fn:contains ( (), "****", "CollationA")
returns true
. The second argument contains only
ignorable collation units and is equivalent to the zerolength string.
Summary: Returns an xs:boolean
indicating whether or not the
value of $arg1
starts with a sequence of collation units that
provides a minimal match to the collation units of $arg2
according to the collation that is used.
"Minimal match" is defined in
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 the invocation of this function is determined according
to the rules in
CollationA used in these examples is a collation in which both "" and "*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation
element" in
fn:startswith("tattoo", "tat")
returns
true
.
fn:startswith ( "tattoo", "att")
returns
false
.
fn:startswith ((), ())
returns true
.
fn:startswith ( "abcdefghi", "abc",
"CollationA")
returns true
.
fn:startswith ( "a*b*c*d*e*f*g*h*i*", "abc",
"CollationA")
returns true
.
fn:startswith ( "abcd***ef**ghi", "abcdef",
"CollationA")
returns true
.
fn:startswith ( (), "****", "CollationA")
returns true
. The second argument contains only
ignorable collation units and is equivalent to the zerolength string.
Summary: Returns an xs:boolean
indicating whether or not the
value of $arg1
ends with a sequence of collation units that
provides a minimal match to the collation units of $arg2
according to the collation that is used.
"Minimal match" is defined in
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 the invocation of this function is determined according
to the rules in
CollationA used in these examples is a collation in which both "" and "*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation
element" in
fn:endswith ( "tattoo", "tattoo")
returns
true
.
fn:endswith ( "tattoo", "atto")
returns
false
.
fn:endswith ((), ())
returns true
.
fn:endswith ( "abcdefghi", "ghi",
"CollationA")
returns true
.
fn:endswith ( "abcd***ef**ghi", "defghi",
"CollationA")
returns true
.
fn:endswith ( "abcd***ef**ghi", "defghi",
"CollationA")
returns true
.
fn:endswith ( (), "****", "CollationA")
returns true
. The second argument contains only
ignorable collation units and is equivalent to the zerolength string.
Summary: 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 minimal match to the collation
units of $arg2
according to the collation that is used.
"Minimal match" is defined in
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 the invocation of this function is determined according
to the rules in
CollationA used in these examples is a collation in which both "" and "*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation
element" in
fn:substringbefore ( "tattoo", "attoo")
returns
. t
fn:substringbefore ( "tattoo", "tatto")
returns .

fn:substringbefore ((), ())
returns
.

fn:substringbefore ( "abcdefghi", "de",
"CollationA")
returns abc
.

fn:substringbefore ( "abcdefghi", "de",
"CollationA")
returns abc
.

fn:substringbefore ( "a*b*c*d*e*f*g*h*i*", "***cde",
"CollationA")
returns a*b*
.

fn:substringbefore ( "Eureka!", "****",
"CollationA")
returns . The second argument
contains only ignorable collation units and is equivalent to the
zerolength string.
fn:substringafter
Summary: 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 minimal match to the collation
units of $arg2
according to the collation that is used.
"Minimal match" is defined in .
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 the invocation of this function is determined according
to the rules in If the specified collation does
not support collation units an error be raised
.
Examples
CollationA used in these examples is a collation in which both "" and
"*" are ignorable collation units.
"Ignorable collation unit" is equivalent to "ignorable collation
element" in .

fn:substringafter("tattoo", "tat")
returns too
.

fn:substringafter ( "tattoo", "tattoo")
returns
.

fn:substringafter ((), ())
returns
.

fn:substringafter ( "abcdefghi", "de",
"CollationA")
returns fghi
.

fn:substringafter ( "abcdefghi", "de",
"CollationA")
returns fghi
.

fn:substringafter ( "a*b*c*d*e*f*g*h*i*", "***cde***",
"CollationA")
returns *f*g*h*i*
.

fn:substringafter ( "Eureka!", "****",
"CollationA")
returns Eureka!
. The second argument contains only ignorable collation
units and is equivalent to the zerolength string.
String Functions that Use Pattern Matching
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 an xs:boolean
value that indicates whether the
value of the first argument is matched by the regular expression
that is the value of the second argument.
fn:replace
Returns the value of the first argument with every substring matched
by the regular expression that is the value of the second argument
replaced by the replacement string that is the value of the third
argument.
fn:tokenize
Returns a sequence of one or more xs:string
s whose
values are substrings of the value of the first argument separated
by substrings that match the regular expression that is the value of
the second argument.
Regular Expression Syntax
The regular expression syntax used by these functions is defined in terms of
the regular expression syntax specified in XML Schema (see ), which in turn is based on the established conventions of
languages such as Perl. However, because XML Schema uses regular expressions
only for validity checking, it omits some facilities that are widelyused
with languages such as Perl. This section, therefore, describes extensions
to the XML Schema regular expressions syntax that reinstate these capabilities.
It is recommended that implementers consult for information on using regular expression processing on Unicode characters.
The regular expression syntax and semantics are identical to those
defined in with the following additions:

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 ::= [^.\?*+{}()^$#x5B#x5D]
The characters #x5B
and #x5D
correspond
to "[
" and "]
" respectively.
The following production:
[11] charClass ::= charClassEsc  charClassExpr  WildCardEsc
is modified to read:
[11] charClass ::= charClassEsc  charClassExpr 
WildCardEsc  "^"  "$"

Reluctant quantifiers are supported. They are
indicated by a
?
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 shortest possible substring consistent
with the match as a whole succeeding. Without the
?
, the regular expression matches the
longest possible substring.
To achieve this, the production in :
[4] quantifier ::= [?*+]  ( '{' quantity '}' )
is changed to:
[4] quantifier ::= ( [?*+]  ( '{' quantity '}' ) ) '?'?
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 allows a regular expression to contain
parenthesized subexpressions, but attaches no special
significance to them. The fn:replace()
function
described below allows access to the parts of the input string
that matched a subexpression (called captured substrings). The
subexpressions are numbered according to the position of the
opening parenthesis in lefttoright order within the toplevel
regular expression: the first opening parenthesis identifies
captured substring 1, the second identifies captured substring
2, and so on. 0 identifies the substring captured by the entire
regular expression. If a subexpression matches more than one
substring (because it is within a construct that allows
repetition), then only the last substring that it
matched will be captured.

Backreferences are allowed. The construct \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
the backreference is preceded by sufficiently many capturing
subexpressions. 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. The closing right
parenthesis of this subexpression must occur before the
backreference. 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.
Backreferences change the following production:
[23] charClassEsc ::= ( SingleCharEsc  MultiCharEsc 
catEsc  complEsc )
to
[23] charClassEsc ::= ( SingleCharEsc  MultiCharEsc 
catEsc  complEsc  backReference )
[23a] backReference ::= "\" [19][09]*

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]
Flags
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 an error
is raised .
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
) character. In dotall mode, the
metacharacter .
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), 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.

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 *casevariant* of
another character C1 if the following XPath expression returns
true
when the two characters
are considered as strings of length one, and the Unicode codepoint
collation is used:
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
) represents the set
containing all the characters that it would match in the absence
of the "i
" 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
fn:matches
Summary: The function returns true
if $input
matches the regular expression supplied as $pattern
as
influenced by the value of $flags
, if present; otherwise, it
returns false
.
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.
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 , where regular expressions are implicitly anchored.
An error is raised if the value of
$pattern
is invalid according to the rules described in section
.
An error is raised if the value of
$flags
is invalid according to the rules described in section
.
Examples

fn:matches("abracadabra", "bra")
returns true

fn:matches("abracadabra", "^a.*a$")
returns true

fn:matches("abracadabra", "^bra")
returns false
Given the source document:
<poem author="Wilhelm Busch">
Kaum hat dies der Hahn gesehen,
Fängt er auch schon an zu krähen:
«Kikeriki! Kikikerikih!!»
Tak, tak, tak!  da kommen sie.
</poem>
the following function calls produce the following results, with the
poem
element as the context node:

fn:matches(., "Kaum.*krähen")
returns false

fn:matches(., "Kaum.*krähen", "s")
returns true

fn:matches(., "^Kaum.*gesehen,$", "m")
returns true

fn:matches(., "^Kaum.*gesehen,$")
returns false

fn:matches(., "kiki", "i")
returns true
Regular expression matching is defined on the basis of Unicode code
points; it takes no account of collations.
fn:replace
Summary: 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.
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.
If two overlapping substrings of $input
both match the
$pattern
, then only the first one (that is, the one whose first
character comes first in the $input
string) is replaced.
Within the $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 characters in $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 $23
and there are 5 substrings, the result contains the value of the substring that matches the second subexpression, followed by the digit 3
.
A literal $
symbol must be written as \$
.
A literal \
symbol 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:
fn:replace("abcd", "(ab)(a)", "[1=$1][2=$2]") returns "[1=ab][2=]cd"
An error is raised if the value of
$pattern
is invalid according to the rules described in section
.
An error is raised if the value of
$flags
is invalid according to the rules described in section
.
An error is raised if the pattern matches
a zerolength string, that is, if the expression fn:matches("",
$pattern, $flags)
returns true
. It is not an error,
however, if a captured substring is zerolength.
An error is raised if the value of
$replacement
contains a "$
" character that is not
immediately followed by a digit 09
and not immediately
preceded by a "\".
An error is raised if the value of
$replacement
contains a "\
" character that is not
part of a "\\
" pair, unless it is immediately followed by a
"$
" character.
Examples

replace("abracadabra", "bra", "*")
returns "a*cada*"

replace("abracadabra", "a.*a", "*")
returns "*"

replace("abracadabra", "a.*?a", "*")
returns "*c*bra"

replace("abracadabra", "a", "")
returns "brcdbr"

replace("abracadabra", "a(.)", "a$1$1")
returns "abbraccaddabbra"

replace("abracadabra", ".*?", "$1")
raises an
error, because the pattern matches the zerolength string

replace("AAAA", "A+", "b")
returns
b

replace("AAAA", "A+?", "b")
returns
bbbb

replace("darted", "^(.*?)d(.*)$", "$1c$2")
returns
carted
. The first
d
is replaced.
fn:tokenize
Summary: This function breaks the $input
string into a sequence
of strings, treating any substring that matches $pattern
as a
separator. The separators themselves are not returned.
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 result is the empty sequence.
If the supplied $pattern
matches a zerolength string, that is,
if fn:matches("", $pattern, $flags)
returns true
,
then an error is raised: .
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:
fn:tokenize("abracadabra", "(ab)(a)") returns ("", "r", "c", "d", "r", "")
An error is raised if the value of
$pattern
is invalid according to the rules described in section
.
An error is raised if the value of
$flags
is invalid according to the rules described in section
.
Examples

fn:tokenize("The cat sat on the mat", "\s+")
returns ("The", "cat", "sat", "on", "the", "mat")

fn:tokenize("1, 15, 24, 50", ",\s*")
returns
("1", "15", "24", "50")

fn:tokenize("1,15,,24,50,", ",")
returns
("1", "15", "", "24", "50", "")

fn:tokenize("abba", ".?")
raises the error
.

fn:tokenize("Some unparsed <br> HTML
<BR> text", "\s*<br>\s*", "i")
returns ("Some unparsed", "HTML", "text")
Functions and Operators for anyURI
This section specifies functions that take anyURI as arguments.
Function
Meaning
fn:resolveuri
Returns an xs:anyURI
representing an absolute
xs:anyURI
given a base URI and a relative URI.
fn:resolveuri
Summary: The purpose of this function is to enable a relative URI to be resolved against an absolute URI.
The first form of
this function resolves $relative
against the value of the baseuri property from the
static context. If the baseuri property is not initialized in the static
context an error is raised .
If $relative
is a relative URI
reference, it is resolved against $base
, or the baseuri property from the
static context, using an algorithm such as the ones described in or , and the
resulting absolute URI reference is returned. An error may be raised in the resolution process.
If $relative
is an
absolute URI reference, it is returned unchanged.
If $relative
or $base
is not a valid
xs:anyURI
an error is raised .
If $relative
is the empty sequence, the empty sequence is returned.
If $relative
is the zerolength string, returns the value of the
baseuri property from the static context in the first form (if the baseuri
property is not initialized in the static context an error is raised
) and $base
in the second form.
Resolving a URI does not dereference it. This is merely a syntactic operation
on two character strings.
Functions and Operators on Boolean Values
This section defines functions and operators on the boolean datatype.
Additional Boolean Constructor Functions
The following additional constructor functions are defined on the boolean type.
Function
Meaning
fn:true
Constructs the xs:boolean value 'true'.
fn:false
Constructs the xs:boolean value 'false'.
fn:true
Summary: Returns the xs:boolean
value true
.
Equivalent to xs:boolean("1")
.
Examples

fn:true()
returns true
.
fn:false
Summary: Returns the xs:boolean
value false
.
Equivalent to xs:boolean("0")
.
Examples

fn:false()
returns false
.
Operators on Boolean Values
The following functions define the semantics of operators on boolean values in
and :
Operator
Meaning
op:booleanequal
Equality of xs:boolean
values
op:booleanlessthan
A lessthan operator on xs:boolean
values:
false
is less than true
.
op:booleangreaterthan
A greaterthan operator on xs:boolean
values:
true
is greater than false
.
The ordering operators op:booleanlessthan
and op:booleangreaterthan
are provided for application purposes
and for compatibility with . The
datatype xs:boolean
is not ordered.
op:booleanequal
Summary: Returns true
if both arguments are true
or
if both arguments are false
. Returns false
if one
of the arguments is true
and the other argument is
false
.
This function backs up the "eq" operator on xs:boolean
values.
op:booleanlessthan
Summary: Returns true
if $arg1
is
false
and $arg2
is true
. Otherwise,
returns false
.
This function backs up the "lt" and "ge" operators on xs:boolean
values.
op:booleangreaterthan
Summary: Returns true
if $arg1
is true
and $arg2
is false
. Otherwise, returns false
.
This function backs up the "gt" and "le" operators on xs:boolean
values.
Functions on Boolean Values
The following functions are defined on boolean values:
Function
Meaning
fn:not
Inverts the xs:boolean
value of the argument.
fn:not
Summary: $arg
is first reduced to an effective boolean value by
applying the fn:boolean()
function. Returns true
if the effective boolean value is false
, and false
if the effective boolean value is true
.
Examples

fn:not(fn:true())
returns false
.

fn:not("false")
returns false
.
Functions and Operators on Durations, Dates and Times
This section discusses operations on the date and time types.
It also discusses operations on two subtypes of xs:duration
that are
defined in this document. See .
See for a disquisition on working with date and time values with and without timezones.
Duration, Date and Time Types
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
Note that only equality is defined on
xs:gYearMonth
, xs:gYear
,
xs:gMonthDay
, xs:gMonth
and xs:gDay
values.
In addition, operators are defined on:

xs:duration
and on the :

xdt:yearMonthDuration

xdt:dayTimeDuration
Note that only equality is defined on
xs:duration
values.
Limits and Precision
For a number of the above datatypes extends the basic
lexical representations, such as
YYYYMMDDThh:mm:ss.s for dateTime, by allowing a preceding minus sign, more
than four digits to represent the year field — no maximum is
specified — and an unlimited number of digits for fractional
seconds. Leap seconds are not supported.
All minimally conforming processors
support positive year values with a minimum of 4 digits (i.e.,
YYYY) and a minimum fractional second precision of 1 millisecond or three
digits (i.e., s.sss). However, conforming processors
set larger limits
on the maximum number of digits they support in these two situations. Processors also choose to support the year 0000 and
years with negative values. The results of operations on dates that cross the year
0000 are .
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 . In
these situations, the processor return P0M or PT0S in
case of duration underflow and 00:00:00 in case of time underflow.
It raise an error in case of overflow.
The value spaces of the two totally ordered subtypes of
xs:duration
described in are
xs:integer
months for xdt:yearMonthDuration
and xs:decimal
seconds for xdt: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
. In these situations the processor
return zero in case of numeric underflow and P0M
or PT0S in case of duration underflow. It raise an
error in case of overflow.
Date/time datatype values
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 value of the first five components are xs:integer
s. The value of the second
component is an xs:decimal
and the value of the timezone
component is an xdt:dayTimeDuration
. For all the 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 absent. Absent, or missing, properties are represented by the empty sequence. This value is referred to as the local value in that the value is in the given timezone. Before comparing or subtracting xs:dateTime
values, this local value be translated or normalized to UTC.
For xs:time
, "00:00:00"
and "24:00:00"
are alternate lexical forms for the same value. For xs:dateTime
,
a time component "24:00:00"
translates to "00:00:00"
of the following day.
Examples

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, ()}
.
Two Totally Ordered Subtypes of Duration
Two totally ordered subtypes of xs:duration
are defined in
specification using the mechanisms described in for
defining userdefined types. They are available in the namespace
http://www.w3.org/2005/xpathdatatypes
.
The XML Schema for these two derived datatypes is shown in . Additional details about these types is given below.
xdt:yearMonthDuration
[Definition] xdt:yearMonthDuration
is derived from
xs:duration
by restricting its lexical representation to
contain only the year and month components. The value space of
xdt:yearMonthDuration
is the set of xs:integer
month values. The year and month components of
xdt:yearMonthDuration
correspond to the Gregorian year and
month components defined in section 5.5.3.2 of , respectively.
Lexical representation
The lexical representation for xdt:yearMonthDuration
is the
reduced format PnYnM, where nY represents
the number of years and nM the number of months. The values of the years
and months components are not restricted but allow an arbitrary unsigned 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 xdt:yearMonthDuration
of 1 year, 2 months, one
would write: P1Y2M. One could also indicate a
xdt: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 be omitted.
However, at least one number and its designator be
present. For example, P1347Y and P1347M are allowed; P1347M is not
allowed, although P1347M is allowed. P1Y2MT is not allowed. Also, P24YM
is not allowed, nor is PY43M since Y must have at least one preceding
digit and M must have one preceding digit.
Calculating the value from the lexical representation
The value of a xdt: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.
Canonical representation
The canonical representation of xdt: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 be
omitted. However, if the value is zero (0) months, the canonical form is "P0M".
Order relation on xdt:yearMonthDuration
Let the function that calculates the value of an
xdt:yearMonthDuration
in the manner described above be
called V(d). Then for two xdt:yearMonthDuration
values x
and y, x > y if and only if V(x) > V(y). The order relation on
yearMonthDuration
is a total order.
xdt:dayTimeDuration
[Definition] xdt: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 xdt:dayTimeDuration
is the set of fractional second
values. The components of xdt:dayTimeDuration
correspond to the
day, hour, minute and second components defined in Section 5.5.3.2 of
, respectively.
Lexical representation
The lexical representation for xdt:dayTimeDuration
is the
truncated format PnDTnHnMnS, where nD
represents the number of days, T is the date/time separator, nH the
number of hours, nM the number of minutes and nS the number of seconds.
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 Date and Time Formats.
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 be omitted. However, at least
one number and its designator be present.

The seconds part have a decimal fraction.

The designator 'T' be absent if and only if
all of the time items are absent. The designator 'P' always be present.
For example, P13D, PT47H, P3DT2H, PT35.89S and P4D251M are all allowed.
P134D is not allowed (invalid location of minus sign), although P134D
is allowed.
Calculating the value of a xdt:dayTimeDuration from the lexical representation
The value of a xdt: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.
Canonical representation
The canonical representation of xdt: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 , Appendix D).
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
.
Order relation on xdt:dayTimeDuration
Let the function that calculates the value of a
xdt:dayTimeDuration
in the manner described above be called
V(d) . Then for two xdt:dayTimeDuration
values
x and y, x > y if and only if V(x)
> V(y) . The order relation on
xdt:dayTimeDuration
is a total order.
Comparisons of Duration, Date and Time Values
Operator
Meaning
op:yearMonthDurationequal
Equality comparison on xdt:yearMonthDuration
values
op:yearMonthDurationlessthan
Lessthan comparison on xdt:yearMonthDuration
values
op:yearMonthDurationgreaterthan
Greaterthan comparison on xdt:yearMonthDuration
values
op:dayTimeDurationequal
Equality comparison on xdt:dayTimeDuration
values
op:dayTimeDurationlessthan
Lessthan comparison on xdt:dayTimeDuration
values
op:dayTimeDurationgreaterthan
Greaterthan comparison on xdt:dayTimeDuration
values
op:durationequal
Equality comparison on xs:duration
values
op:dateTimeequal
Equality comparison on xs:dateTime
values
op:dateTimelessthan
Lessthan comparison on xs:dateTime
values
op:dateTimegreaterthan
Greaterthan comparison on xs:dateTime
values
op:dateequal
Equality comparison on xs:date
values
op:datelessthan
Lessthan comparison on xs:date
values
op:dategreaterthan
Greaterthan comparison on xs:date
values
op:timeequal
Equality comparison on xs:time
values
op:timelessthan
Lessthan comparison on xs:time
values
op:timegreaterthan
Greaterthan comparison on xs:time
values
op:gYearMonthequal
Equality comparison on xs:gYearMonth
values
op:gYearequal
Equality comparison on xs:gYear
values
op:gMonthDayequal
Equality comparison on xs:gMonthDay
values
op:gMonthequal
Equality comparison on xs:gMonth
values
op:gDayequal
Equality comparison on xs:gDay
values
The following comparison operators are defined on the
date, time and duration datatypes. Each operator takes two operands of the same
type and returns an xs:boolean
result. As discussed in , the
order relation on xs:duration
is
not a total order but, rather, a partial 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
which do have a total order.
also states that the
order relation on date and time datatypes is
not a total order but a partial order because these
datatypes may or may not have a timezone. This is handled as follows.
If either operand to a comparison function on date or time values does not have
an (explicit) timezone then, for the purpose of the operation, an implicit
timezone, provided by the dynamic context , is assumed to be present as part of
the value. This creates a total order for all date and time values.
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 absent or missing. 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.
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
. If the value filled in for a missing day component exceeds the maximum day value for the month, the last day of the month is used. Suppose, for example, that the reference xs:dateTime
is 19721231T00:00:00
and the xs:date
value to be compared is 19930331
. Filling in the time components from the reference xs:dateTime
we get 19930331T00:00:00
which is the starting instant of that day. Similarly, if the xs:time
value 12:30:00
is to be compared, we fill in the missing components from the reference xs:dateTime
and we get 19721231T12:30:00
which is the time on that day. For an xs:gYearMonth
value of 197602
we fill in the missing components, adjust for the last day in the month and get 19760229T00:00:00
.
If the xs:time
value written as
24:00:00
is to be compared, filling in the missing components gives 19721231T00:00:00
, 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 proposal uses the reference xs:dateTime 19721231T00:00:00
in the description of the comparison operators. Implementations are allowed to 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.
op:yearMonthDurationequal
Summary: Returns true
if and only if $arg1
is equal
to $arg2
. Returns false
otherwise.
This function backs up the "eq", "ne", "le" and "ge" operators on
xdt:yearMonthDuration
values.
op:yearMonthDurationlessthan
Summary: Returns true
if and only if $arg1
is less
than $arg2
. Returns false
otherwise.
This function backs up the "lt" and "le" operators on
xdt:yearMonthDuration
values.
op:yearMonthDurationgreaterthan
Summary: Returns true
if and only if $arg1
is
greater than $arg2
. Returns false
otherwise.
This function backs up the "gt" and "ge" operators on
xdt:yearMonthDuration
values.
op:dayTimeDurationequal
Summary: Returns true
if and only if the value of
$arg1
is equal to the value of $arg2
. Returns
false
otherwise.
This function backs up the "eq", "ne", "le" and "ge" operators on
xdt:dayTimeDuration
values.
op:dayTimeDurationlessthan
Summary: Returns true
if and only if $arg1
is less
than $arg2
. Returns false
otherwise.
This function backs up the "lt" and "le" operators on
xdt:dayTimeDuration
values.
op:dayTimeDurationgreaterthan
Summary: Returns true
if and only if $arg1
is
greater than $arg2
. Returns false
otherwise.
This function backs up the "gt" and "ge" operators on
xdt:dayTimeDuration
values.
op:durationequal
Summary:
Returns true
if and only if the
xdt:yearMonthDuration
and the xdt:dayTimeDuration
components of $arg1
and $arg2
compare equal respectively.
Returns false
otherwise.
This function backs up the "eq" and "ne" operators on
xs:duration
values.
The semantics of this function are:
if (cast as xdt:yearMonthDuration ($arg1) eq
cast as xdt:yearMonthDuration($arg2)
and
cast as xdt:dayTimeDuration($arg1) eq
cast as xdt:dayTimeDuration ($arg2)) return fn:true()
else return fn:false()
Examples
op:durationequal(xs:duration("P1Y"), xs:duration("P12M"))
returns true
.
op:durationequal(xs:duration("PT24H"), xs:duration("P1D"))
returns true
.
op:durationequal(xs:duration("P1Y"), xs:duration("P365D"))
returns false
.
op:dateTimeequal
Summary:
Returns true
if and only if the value of
$arg1
is equal to the 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.
Returns false
otherwise.
This function backs up the "eq", "ne", "le" and "ge" operators on
xs:dateTime
values.
Examples
Assume that the dynamic context provides an implicit timezone value of 05:00
.

op:dateTimeequal(xs:dateTime("20020402T12:00:0001:00"),
xs:dateTime("20020402T17:00:00+04:00"))
returns true
.

op:dateTimeequal(xs:dateTime("20020402T12:00:00"),
xs:dateTime("20020402T23:00:00+06:00"))
returns true
.

op:dateTimeequal(xs:dateTime("20020402T12:00:00"),
xs:dateTime("20020402T17:00:00"))
returns false
.

op:dateTimeequal(xs:dateTime("20020402T12:00:00"),
xs:dateTime("20020402T12:00:00"))
returns true
.

op:dateTimeequal(xs:dateTime("20020402T23:00:0004:00"),
xs:dateTime("20020403T02:00:0001:00"))
returns true
.

op:dateTimeequal(xs:dateTime("19991231T24:00:00"),
xs:dateTime("20000101T00:00:00"))
returns true
.

op:dateTimeequal(xs:dateTime("20050404T24:00:00"),
xs:dateTime("20050404T00:00:00"))
returns false
.
op:dateTimelessthan
Summary: Returns true
if and only if the value of
$arg1
is less than the 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.
Returns false
otherwise.
This function backs up the "lt" and "le" operators on
xs:dateTime
values.
op:dateTimegreaterthan
Summary: Returns true
if and only if the value of
$arg1
is greater than the 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.
Returns false
otherwise.
This function backs up the "gt" and "ge" operators on
xs:dateTime
values.
op:dateequal
Summary: Returns true
if and only if the starting instant of
$arg1
is equal to starting instant of $arg2
.
Returns false
otherwise.
The starting instant of an xs:date
is the xs:dateTime
at time 00:00:00
on that date.
The two starting instants are compared using op:dateTimeequal
.
This function backs up the "eq", "ne", "le" and "ge" operators on xs:date
values.
Examples

op:dateequal(xs:date("20041225Z"),
xs:date("20041225+07:00"))
returns false
. The starting instants are 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")
.

op:dateequal(xs:date("2004122512:00"),
xs:date("20041226+12:00"))
returns true
.
op:datelessthan
Summary: Returns true
if and only if the starting instant of
$arg1
is less than the starting instant of $arg2
.
Returns false
otherwise.
The starting instant of an xs:date
is the xs:dateTime
at time 00:00:00
on that date.
The two starting instants are compared using op:dateTimelessthan
.
This function backs up the "lt" and "le" operators on xs:date
values.
Examples

op:datelessthan(xs:date("20041225Z"),
xs:date("2004122505:00"))
returns true
.

op:datelessthan(xs:date("2004122512:00"),
xs:date("20041226+12:00"))
returns false
.
op:dategreaterthan
Summary: Returns true
if and only if the starting instant of
$arg1
is greater than the starting instant of $arg2
. Returns false
otherwise.
The starting instant of an xs:date
is the xs:dateTime
at time 00:00:00
on that date.
The two starting instants are compared using op:dateTimegreaterthan
.
This function backs up the "gt" and "ge" operators on xs:date
values.
Examples

op:dategreaterthan(xs:date("20041225Z"),
xs:date("20041225+07:00"))
returns true
.

op:dategreaterthan(xs:date("2004122512:00"),
xs:date("20041226+12:00"))
returns false
.
op:timeequal
Summary: Returns true
if and only if the value of
$arg1
converted to an xs:dateTime
using the date components from the reference xs:dateTime
is equal to the value of $arg2
converted to an xs:dateTime
using the date components from the same reference xs:dateTime
.
Returns false
otherwise.
The two xs:dateTime
values are compared using op:dateTimeequal
.
This function backs up the "eq", "ne", "le" and "ge" operators on xs:time
values.
Examples
Assume that the date components from the reference xs:dateTime
correspond to 19721231
.

op:timeequal(xs:time("08:00:00+09:00"),
xs:time("17:00:0006:00"))
returns false
. The 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 19721231T23:00:00
.

op:timeequal(xs:time("21:30:00+10:30"),
xs:time("06:00:0005:00"))
returns true
.

op:timeequal(xs:time("24:00:00+01:00"), xs:time("00:00:00+01:00"))
returns true
.
op:timelessthan
Summary: Returns true
if and only if the value of
$arg1
converted to an xs:dateTime
using the date components from the reference xs:dateTime
is less than the normalized value of $arg2
converted to an xs:dateTime
using the date components from the same reference xs:dateTime
.
Returns false
otherwise.
The two xs:dateTime
values are compared using op:dateTimelessthan
.
This function backs up the "lt" and "le" operators on xs:time
values.
Examples
Assume that the dynamic context provides an implicit timezone value of 05:00
.

op:timelessthan(xs:time("12:00:00"),
xs:time("23:00:00+06:00"))
returns false
.

op:timelessthan(xs:time("11:00:00"),
xs:time("17:00:00Z"))
returns true
.

op:timelessthan(xs:time("23:59:59"), xs:time("24:00:00"))
returns false
.
op:timegreaterthan
Summary: Returns true
if and only if the value of
$arg1
converted to an xs:dateTime
using the date components from the reference xs:dateTime
is greater than the value of
$arg2
converted to an xs:dateTime
using the date components from the same reference xs:dateTime
. Returns false
otherwise.
The two xs:dateTime
values are compared using op:dateTimegreaterthan
.
This function backs up the "gt" and "ge" operators on xs:time
values.
Examples

op:timegreaterthan(xs:time("08:00:00+09:00"),
xs:time("17:00:0006:00"))
returns false
.
op:gYearMonthequal
Summary: Returns true
if and only if the xs:dateTime
s representing the starting instants of $arg1
and $arg2
compare equal. The starting instants of $arg1
and $arg2
are calculated by adding the missing components of $arg1
and $arg2
from the xs:dateTime
template xxxxxxddT00:00:00
where dd
represents the last day of the month
component in $arg1
or $arg2
. Returns false
otherwise.
The two xs:dateTime
values representing the starting instants of $arg1
and $arg2
are compared using op:dateTimeequal
.
This function backs up the "eq" and "ne" operators on
xs:gYearMonth
values.
Examples
Assume that the dynamic context provides an implicit timezone value of 05:00
.

op:gYearMonthequal(xs:gYearMonth("197602"),
xs:gYearMonth("197603Z"))
returns false
. The starting instants are 19720229T00:00:0005:00
and 19720331T00:00:00Z
, respectively.

op:gYearMonthequal(xs:gYearMonth("197603"),
xs:gYearMonth("197603Z"))
returns false
.
op:gYearequal
Summary: Returns true
if and only if the xs:dateTime
s representing the starting instants of $arg1
and $arg2
compare equal. The starting instants of $arg1
and $arg2
are calculated by adding the missing components of $arg1
and $arg2
from a xs:dateTime
template such as xxxx0101T00:00:00
. Returns false
otherwise.
The two xs:dateTime
values representing the starting instants of $arg1
and $arg2
are compared using op:dateTimeequal
.
This function backs up the "eq" and "ne" operators on xs:gYear
values.
Examples
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 200501015T12:00:00Z
and 20041231T12:00:00Z
.

op:gYearequal(xs:gYear("197605:00"),
xs:gYear("1976"))
returns true
.
op:gMonthDayequal
Summary: Summary: Returns true
if and only if the xs:dateTime
s representing the starting instants of equivalent occurrences of $arg1
and $arg2
compare equal. The starting instants of equivalent occurrences of $arg1
and $arg2
are calculated by adding the missing components of $arg1
and $arg2
from an xs:dateTime
template such as 1972xxxxT00:00:00
. Returns false
otherwise.
The two xs:dateTime
values representing the starting instants of equivalent occurrences of $arg1
and $arg2
are compared using op:dateTimeequal
.
This function backs up the "eq" and "ne" operators on
xs:gMonthDay
values.
Examples
Assume that the dynamic context provides an implicit timezone value of 05:00
. Assume, also, that the xs:dateTime
template is 1976xxxxT00:00:00
.

op:gMonthDayequal(xs:gMonthDay("122514:00"),
xs:gMonthDay("1226+10:00"))
returns true
. The starting instants are 19761225T00:00:0014:00
and 19761226T00:00:00+10:00
, respectively, and normalize to 19761225T14:00:00Z
and 19761225T14:00:00Z
.

op:gMonthDayequal(xs:gMonthDay("1225"),
xs:gMonthDay("1226Z"))
returns false
.
op:gMonthequal
Summary: Returns true
if and only if the xs:dateTime
s representing the starting instants of equivalent occurrences of $arg1
and $arg2
compare equal. The starting instants of equivalent occurrences of $arg1
and $arg2
are calculated by adding the missing components of $arg1
and $arg2
from an xs:dateTime
template such as 1972xxddT00:00:00
where dd
represents the last day of the month component in $arg1
or $arg2
. Returns false
otherwise.
The two xs:dateTime
values representing the starting instants of equivalent occurrences of $arg1
and $arg2
are compared using op:dateTimeequal
.
This function backs up the "eq" and "ne" operators on xs:gMonth
values.
Examples
Assume that the dynamic context provides an implicit timezone value of 05:00
. Assume, also, that the xs:dateTime
template is 1972xxddT00:00:00
.

op:gMonthequal(xs:gMonth("1214:00"),
xs:gMonth("12+10:00")
returns false
. The starting instants are 19721231T00:00:0014:00
and 19721231T00:00:00+10:00
, respectively, and normalize to 19720101T14:00:00Z
and 19721230T14:00:00Z
.

op:gMonthequal(xs:gMonth("12"),
xs:gMonth("12Z"))
returns false
.
op:gDayequal
Summary: Returns true
if and only if the xs:dateTime
s representing the starting instants of equivalent occurrences of $arg1
and $arg2
compare equal. The starting instants of equivalent occurrences of $arg1
and $arg2
are calculated by adding the missing components of $arg1
and $arg2
from an xs:dateTime
template such as 197212xxT00:00:00
. Returns false
otherwise.
The two xs:dateTime
values representing the starting instants of equivalent occurrences of $arg1
and $arg2
are compared using op:dateTimeequal
.
This function backs up the "eq" and "ne" operators on xs:gDay
values.
Examples
Assume that the dynamic context provides an implicit timezone value of 05:00
. Assume, also, that the xs:dateTime
template is 1976xxxxT00:00:00
.

op:gDayequal(xs:gDay("2514:00"),
xs:gDay("25+10:00"))
returns false
. The starting instants are 19721225T00:00:0014:00
and 19721225T00:00:00+10:00
, respectively, and normalize to 19721225T14:00:00Z
and 19721224T14:00:00Z
.

op:gDayequal(xs:gDay("12"),
xs:gDay("12Z"))
returns false
.
Component Extraction Functions on Durations, Dates and Times
The duration, 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 duration, date or time value. For
the date/time datatypes the local value is used.
Function
Meaning
fn:yearsfromduration
Returns the year component of an xdt:yearMonthDuration
value.
fn:monthsfromduration
Returns the months component of an
xdt:yearMonthDuration
value.
fn:daysfromduration
Returns the days component of an xdt:dayTimeDuration
value.
fn:hoursfromduration
Returns the hours component of an xdt:dayTimeDuration
value.
fn:minutesfromduration
Returns the minutes component of an xdt:dayTimeDuration
value.
fn:secondsfromduration
Returns the seconds component of an xdt:dayTimeDuration
value.
fn:yearfromdateTime
Returns the year from an xs:dateTime
value.
fn:monthfromdateTime
Returns the month from an xs:dateTime
value.
fn:dayfromdateTime
Returns the day from an xs:dateTime
value.
fn:hoursfromdateTime
Returns the hours from an xs:dateTime
value.
fn:minutesfromdateTime
Returns the minutes from an xs:dateTime
value.
fn:secondsfromdateTime
Returns the seconds from an xs:dateTime
value.
fn:timezonefromdateTime
Returns the timezone from an xs:dateTime
value.
fn:yearfromdate
Returns the year from an xs:date
value.
fn:monthfromdate
Returns the month from an xs:date
value.
fn:dayfromdate
Returns the day from an xs:date
value.
fn:timezonefromdate
Returns the timezone from an xs:date
value.
fn:hoursfromtime
Returns the hours from an xs:time
value.
fn:minutesfromtime
Returns the minutes from an xs:time
value.
fn:secondsfromtime
Returns the seconds from an xs:time
value.
fn:timezonefromtime
Returns the timezone from an xs:time
value.
fn:yearsfromduration
Summary: Returns an xs:integer
representing the years component
in the canonical lexical representation of the value of $arg
.
The result may be negative.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:yearsfromduration(xdt:yearMonthDuration("P20Y15M"))
returns 21
.

fn:yearsfromduration(xdt:yearMonthDuration("P15M"))
returns 1
.
fn:monthsfromduration
Summary: Returns an xs:integer
representing the months component
in the canonical lexical representation of the value of $arg
.
The result may be negative.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:monthsfromduration(xdt:yearMonthDuration("P20Y15M"))
returns 3
.

fn:monthsfromduration(xdt:yearMonthDuration("P20Y18M"))
returns 6
.
fn:daysfromduration
Summary: Returns an xs:integer
representing the days component
in the canonical lexical representation of the value of $arg
.
The result may be negative.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:daysfromduration(xdt:dayTimeDuration("P3DT10H"))
returns 3
.

fn:daysfromduration(xdt:dayTimeDuration("P3DT55H"))
returns 5
.
fn:hoursfromduration
Summary: Returns an xs:integer
representing the hours component
in the canonical lexical representation of the value of $arg
.
The result may be negative.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:hoursfromduration(xdt:dayTimeDuration("P3DT10H"))
returns 10
.

fn:hoursfromduration(xdt:dayTimeDuration("P3DT12H32M12S"))
returns 12
.

fn:hoursfromduration(xdt:dayTimeDuration("PT123H"))
returns 3
.

fn:hoursfromduration(xdt:dayTimeDuration("P3DT10H"))
returns 10
.
fn:minutesfromduration
Summary: Returns an xs:integer
representing the minutes
component in the canonical lexical representation of the value of
$arg
. The result may be negative.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:minutesfromduration(xdt:dayTimeDuration("P3DT10H"))
returns 0
.

fn:minutesfromduration(xdt:dayTimeDuration("P5DT12H30M"))
returns 30
.
fn:secondsfromduration
Summary: Returns an xs:decimal
representing the seconds
component in the canonical lexical representation of the value of
$arg
. The result may be negative.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:secondsfromduration(xdt:dayTimeDuration("P3DT10H12.5S"))
returns 12.5
.

fn:secondsfromduration(xdt:dayTimeDuration("P256S"))
returns 16.0
.
fn:yearfromdateTime
Summary: Returns an xs:integer
representing the year component
in the localized value of $arg
. The result may be negative.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:yearfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 1999
.

fn:yearfromdateTime(xs:dateTime("19990531T21:30:0005:00"))
returns 1999
.

fn:yearfromdateTime(xs:dateTime("19991231T19:20:00"))
returns 1999
.

fn:yearfromdateTime(xs:dateTime("19991231T24:00:00"))
returns 2000
.
fn:monthfromdateTime
Summary: Returns an xs:integer
between 1 and 12, both inclusive,
representing the month component in the localized value of $arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:monthfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 5
.

fn:monthfromdateTime(xs:dateTime("19991231T19:20:0005:00"))
returns 12
.

fn:monthfromdateTime(fn:adjustdateTimetotimezone(xs:dateTime("19991231T19:20:0005:00"),
xdt:dayTimeDuration("PT0S")))
returns 1
.
fn:dayfromdateTime
Summary: Returns an xs:integer
between 1 and 31, both inclusive,
representing the day component in the localized value of $arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:dayfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 31
.

fn:dayfromdateTime(xs:dateTime("19991231T20:00:0005:00"))
returns 31
.

fn:dayfromdateTime(fn:adjustdateTimetotimezone(xs:dateTime("19991231T19:20:0005:00"),
xdt:dayTimeDuration("PT0S")))
returns 1
.
fn:hoursfromdateTime
Summary: Returns an xs:integer
between 0 and 23, both inclusive,
representing the hours component in the localized value of $arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:hoursfromdateTime(xs:dateTime("19990531T08:20:0005:00"))
returns 8
.

fn:hoursfromdateTime(xs:dateTime("19991231T21:20:0005:00"))
returns 21
.

fn:hoursfromdateTime(fn:adjustdateTimetotimezone(xs:dateTime("19991231T21:20:0005:00"),
xdt:dayTimeDuration("PT0S")))
returns
2
.

fn:hoursfromdateTime(xs:dateTime("19991231T12:00:00"))
returns 12
.

fn:hoursfromdateTime(xs:dateTime("19991231T24:00:00"))
returns 0
.
fn:minutesfromdateTime
Summary: Returns an xs:integer
value between 0 and 59, both
inclusive, representing the minute component in the localized value of $arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:minutesfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 20
.

fn:minutesfromdateTime(xs:dateTime("19990531T13:30:00+05:30"))
returns 30
.
fn:secondsfromdateTime
Summary: Returns an xs:decimal
value greater than or equal to zero and less than 60,
representing the seconds and fractional seconds in the
localized value of $arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:secondsfromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns 0
.
fn:timezonefromdateTime
Summary: Returns the timezone component of $arg
if any. If
$arg
has a timezone component, then the result is
an xdt:dayTimeDuration
that indicates deviation from UTC; its
value may range from +14:00 to 14:00 hours, both inclusive. Otherwise, the
result is the empty sequence.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:timezonefromdateTime(xs:dateTime("19990531T13:20:0005:00"))
returns the xdt:dayTimeDuration
whose value is
PT5H
.

fn:timezonefromdateTime(xs:dateTime("20000612T13:20:00Z"))
returns the xdt:dayTimeDuration
whose value is
PT0S
.

fn:timezonefromdateTime(xs:dateTime("20040827T00:00:00"))
returns ()
.
fn:yearfromdate
Summary: Returns an xs:integer
representing the year in the
localized value of $arg
. The value may be negative.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:yearfromdate(xs:date("19990531"))
returns
1999
.

fn:yearfromdate(xs:date("20000101+05:00"))
returns 2000
.
fn:monthfromdate
Summary: Returns an xs:integer
between 1 and 12, both inclusive,
representing the month component in the localized value of
$arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:monthfromdate(xs:date("1999053105:00"))
returns 5
.

fn:monthfromdate(xs:date("20000101+05:00"))
returns 1
.
fn:dayfromdate
Summary: Returns an xs:integer
between 1 and 31, both inclusive,
representing the day component in the localized value of $arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:dayfromdate(xs:date("1999053105:00"))
returns 31
.

fn:dayfromdate(xs:date("20000101+05:00"))
returns 1
.
fn:timezonefromdate
Summary: Returns the timezone component of $arg
if any. If
$arg
has a timezone component, then the result is
an xdt:dayTimeDuration
that indicates deviation from UTC; its
value may range from +14:00 to 14:00 hours, both inclusive. Otherwise, the
result is the empty sequence.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:timezonefromdate(xs:date("1999053105:00"))
returns the xdt:dayTimeDuration
whose value is
PT5H
.

fn:timezonefromdate(xs:date("20000612Z"))
returns the xdt:dayTimeDuration
with value PT0S
.
fn:hoursfromtime
Summary: Returns an xs:integer
between 0 and 23, both inclusive,
representing the value of the hours component in the localized value of $arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples
Assume that the dynamic context provides an implicit timezone value of 05:00
.

fn:hoursfromtime(xs:time("11:23:00"))
returns
11
.

fn:hoursfromtime(xs:time("21:23:00"))
returns
21
.

fn:hoursfromtime(xs:time("01:23:00+05:00"))
returns 1
.

fn:hoursfromtime(fn:adjusttimetotimezone(xs:time("01:23:00+05:00"),
xdt:dayTimeDuration("PT0S")))
returns 20
.

fn:hoursfromtime(xs:time("24:00:00"))
returns 0
.
fn:minutesfromtime
Summary: Returns an xs:integer
value between 0 and 59, both
inclusive, representing the value of the minutes component in the localized
value of $arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:minutesfromtime(xs:time("13:00:00Z"))
returns
0
.
fn:secondsfromtime
Summary: Returns an xs:decimal
value greater than or equal to zero and less than 60, representing the seconds and fractional seconds in the
localized value of $arg
.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:secondsfromtime(xs:time("13:20:10.5"))
returns
10.5
.
fn:timezonefromtime
Summary: Returns the timezone component of $arg
if any. If
$arg
has a timezone component, then the result is
an xdt:dayTimeDuration
that indicates deviation from UTC; its
value may range from +14:00 to 14:00 hours, both inclusive. Otherwise, the
result is the empty sequence.
If $arg
is the empty sequence, returns the empty sequence.
Examples

fn:timezonefromtime(xs:time("13:20:0005:00"))
returns xdt:dayTimeDuration
whose value is PT5H
.

fn:timezonefromtime(xs:time("13:20:00"))
returns ()
.
Arithmetic Functions on Durations
Function
Meaning
op:addyearMonthDurations
Adds two xdt:yearMonthDuration
s. Returns an xdt:yearMonthDuration
.
op:subtractyearMonthDurations
Subtracts one xdt:yearMonthDuration
from another.
Returns an xdt:yearMonthDuration
.
op:multiplyyearMonthDuration
Multiplies a xdt:yearMonthDuration
by an
xs:double
. Returns an xdt:yearMonthDuration
.
op:divideyearMonthDuration
Divides an xdt:yearMonthDuration
by an
xs:double
. Returns an xdt:yearMonthDuration
.
op:divideyearMonthDurationbyyearMonthDuration
Divides an xdt:yearMonthDuration
by an
xdt:yearMonthDuration
. Returns an xs:decimal
.
op:adddayTimeDurations
Adds two xdt:dayTimeDurations
. Returns an xdt:dayTimeDuration
.
op:subtractdayTimeDurations
Subtracts one xdt:dayTimeDuration
from another. Returns
an xdt:dayTimeDuration
.
op:multiplydayTimeDuration
Multiplies an xdt:dayTimeDuration
by a
xs:double
. Returns an xdt:dayTimeDuration
.
op:dividedayTimeDuration
Divides an xdt:dayTimeDuration
by an
xs:double
. Returns an xdt:dayTimeDuration
.
op:dividedayTimeDurationbydayTimeDuration
Divides an xdt:dayTimeDuration
by an
xdt:dayTimeDuration
. Returns an xs:decimal
.
op:addyearMonthDurations
Summary: Returns the result of adding the value of $arg1
to the
value of $arg2
. Backs up the "+" operator on
xdt:yearMonthDuration
values.
Examples

op:addyearMonthDurations(xdt:yearMonthDuration("P2Y11M"),
xdt:yearMonthDuration("P3Y3M"))
returns a
xdt:yearMonthDuration
value corresponding to 6
years and 2 months.
op:subtractyearMonthDurations
Summary: Returns the result of subtracting the value of $arg2
from the value of $arg1
. Backs up the "" operator on
xdt:yearMonthDuration
values.
Examples

op:subtractyearMonthDurations(xdt:yearMonthDuration("P2Y11M"),
xdt:yearMonthDuration("P3Y3M"))
returns a
xdt:yearMonthDuration
value corresponding to
negative 4 months.
op:multiplyyearMonthDuration
Summary: Returns the result of multiplying the value of $arg1
by
$arg2
. The result is rounded to the nearest month. For a value
v , 0 <= v < 0.5 rounds to 0; 0.5
<= v < 1.0 rounds to 1.
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 . If $arg2
is
NaN
an error is raised
Backs up the "*" operator on xdt:yearMonthDuration
values.
Examples

op:multiplyyearMonthDuration(xdt:yearMonthDuration("P2Y11M"),
2.3)
returns a xdt:yearMonthDuration
value
corresponding to 6 years and 9 months.
op:divideyearMonthDuration
Summary: Returns the result of dividing the value of $arg1
by
$arg2
. The result is rounded to the nearest month. For a value
v , 0 <= v < 0.5 rounds to 0; 0.5
<= v < 1.0 rounds to 1.
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 . If $arg2
is
NaN
an error is raised
Backs up the "div" operator on xdt:yearMonthDuration
and numeric values.
Examples

op:divideyearMonthDuration(xdt:yearMonthDuration("P2Y11M"),
1.5)
returns a xdt:yearMonthDuration
value
corresponding to 1 year and 11 months.
op:divideyearMonthDurationbyyearMonthDuration
Summary: Returns the result of dividing the value of $arg1
by $arg2
. Since the values of both operands are integers, the
semantics of the division is identical to op:numericdivide
with
xs:integer
operands.
Backs up the "div" operator on xdt:yearMonthDuration
values.
Examples

op:divideyearMonthDurationbyyearMonthDuration(xdt:yearMonthDuration("P3Y4M"),
xdt:yearMonthDuration("P1Y4M"))
returns
2.5
.
op:adddayTimeDurations
Summary: Returns the result of adding the value of $arg1
to the
value of $arg2
. Backs up the "+" operator on
xdt:dayTimeDuration
values.
Examples

op:adddayTimeDurations(xdt:dayTimeDuration("P2DT12H5M"),
xdt:dayTimeDuration("P5DT12H"))
returns a
xdt:dayTimeDuration
value corresponding to 8 days
and 5 minutes.
op:subtractdayTimeDurations
Summary: Returns the result of subtracting the value of $arg2
from the value of $arg1
. Backs up the "" operator on
xdt:dayTimeDuration
values.
Examples

op:subtractdayTimeDurations(xdt:dayTimeDuration("P2DT12H"),
xdt:dayTimeDuration("P1DT10H30M"))
returns a
xdt:dayTimeDuration
value corresponding to 1 day, 1
hour and 30 minutes.
op:multiplydayTimeDuration
Summary: Returns the result of multiplying the value of $arg1
by $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 . If $arg2
is
NaN
an error is raised
Backs up the "*" operator on xdt:dayTimeDuration
values.
Examples

op:multiplydayTimeDuration(xdt:dayTimeDuration("PT2H10M"),
2.1)
returns a xdt:dayTimeDuration
value
corresponding to 4 hours and 33 minutes.
op:dividedayTimeDuration
Summary: Returns the result of dividing the value of $arg1
by
$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 . If $arg2
is
NaN
an error is raised
Backs up the "div" operator on xdt:dayTimeDuration
values.
Examples

op:dividedayTimeDuration(xdt:yearMonthDuration("P1DT2H30M10.5S"),
1.5)
returns a xdt:dayTimeDuration
value
corresponding to 17 hours, 40 minutes and 7 seconds.
op:dividedayTimeDurationbydayTimeDuration
Summary: Returns the result of dividing the value of $arg1
by $arg2
. Since the values of both operands are decimals, the
semantics of the division is identical to op:numericdivide
with
xs:decimal
operands.
Backs up the "div" operator on xdt:dayTimeDuration
values.
Examples

op:dividedayTimeDurationbydayTimeDuration(xdt:dayTimeDuration("P2DT53M11S"),
xdt:dayTimeDuration("P1DT10H))
returns 1.4378349...
Timezone Adjustment on Dates and Time Values
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.
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 xdt:dayTimeDuration
but must be a valid timezone value.
fn:adjustdateTimetotimezone
Summary: Adjusts an xs:dateTime
value to a specific timezone, or
to no timezone at all. If $timezone
is the empty sequence,
returns an xs:dateTime
without a timezone. Otherwise, returns
an xs:dateTime
with a timezone.
If $timezone
is not specified, then $timezone
is
the value of the implicit timezone in the dynamic context.
If $arg
is the empty sequence, then the result is the empty sequence.
A dynamic error is raised if
$timezone
is less than PT14H
or greater than PT14H
or if does not contain an integral number of minutes.
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 the result is an xs:dateTime
value
with a timezone component of $timezone
that is equal to $arg
.
Examples
Assume the dynamic context provides an implicit timezone of 05:00 (PT5H0M)
.
let $tz := xdt:dayTimeDuration("PT10H")

fn:adjustdateTimetotimezone(xs:dateTime("20020307T10:00:00"))
returns 20020307T10:00:0005:00

fn:adjustdateTimetotimezone(xs:dateTime("20020307T10:00:0007:00"))
returns 20020307T12:00:0005:00

fn:adjustdateTimetotimezone(xs:dateTime("20020307T10:00:00"),
$tz)
returns 20020307T10:00:0010:00

fn:adjustdateTimetotimezone(xs:dateTime("20020307T10:00:0007:00"),
$tz)
returns 20020307T07:00:0010:00

fn:adjustdateTimetotimezone(xs:dateTime("20020307T10:00:0007:00"),
xdt:dayTimeDuration("PT10H"))
returns 20020308T03:00:00+10:00

fn:adjustdateTimetotimezone(xs:dateTime("20020307T00:00:00+01:00"),
xdt:dayTimeDuration("PT8H"))
returns 20020306T15:00:0008:00

fn:adjustdateTimetotimezone(xs:dateTime("20020307T10:00:00"),
())
returns 20020307T10:00:00

fn:adjustdateTimetotimezone(xs:dateTime("20020307T10:00:0007:00"),
())
returns 20020307T10:00:00
fn:adjustdatetotimezone
Summary: Adjusts an xs:date
value to a specific timezone, or to
no timezone at all. If $timezone
is the empty sequence, returns
an xs:date
without a timezone. Otherwise, returns an
xs:date
with a timezone. For purposes of timezone adjustment,
an xs:date
is treated as an xs:dateTime
with time 00:00:00
.
If $timezone
is not specified, then $timezone
is
the value of the implicit timezone in the dynamic context.
If $arg
is the empty sequence, then the result is the empty sequence.
A dynamic error is raised if
$timezone
is less than PT14H
or greater than PT14H
or if does not contain an integral number of minutes.
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 localized value of
$arg
without its timezone component.
If $arg
has a timezone component and $timezone
is
not the empty sequence, then:

Let $srcdt
be an xs:dateTime
value, with
00:00:00
for the time component and date and timezone
components that are the same as the date and timezone components of $arg
.

Let $r
be the result of evaluating
fn:adjustdateTimetotimezone($srcdt, $timezone)

The result of this function will be a date value that has date and
timezone components that are the same as the date and timezone
components of $r
.
Examples
Assume the dynamic context provides an implicit timezone of 05:00 (PT5H0M)
.
let $tz := xdt:dayTimeDuration("PT10H")

fn:adjustdatetotimezone(xs:date("20020307"))
returns 2002030705:00.

fn:adjustdatetotimezone(xs:date("2002030707:00"))
returns 2002030705:00
.$arg
is
converted to the xs:dateTime
"20020307T00:00:0007:00"
. This is adjusted to the
implicit timezone, giving "20020307T02:00:0005:00".

fn:adjustdatetotimezone(xs:date("20020307"),
$tz)
returns 2002030710:00
.

fn:adjustdatetotimezone(xs:date("2002030707:00"),
$tz)
returns 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"
.

fn:adjustdatetotimezone(xs:date("20020307"),
())
returns 20020307.

fn:adjustdatetotimezone(xs:date("2002030707:00"),
())
returns 20020307.
fn:adjusttimetotimezone
Summary: Adjusts an xs:time
value to a specific timezone, or to
no timezone at all. If $timezone
is the empty sequence, returns
an xs:time
without a timezone. Otherwise, returns an
xs:time
with a timezone.
If $timezone
is not specified, then $timezone
is
the value of the implicit timezone in the dynamic context.
If $arg
is the empty sequence, then the result is the empty sequence.
A dynamic error is raised if
$timezone
is less than PT14H
or greater than PT14H
or if does not contain an integral number of minutes.
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 $srcdt
be an xs:dateTime
value, with
an arbitrary date for the date component and time and timezone
components that are the same as the time and timezone components of $arg
.

Let $r
be the result of evaluating
fn:adjustdateTimetotimezone($srcdt, $timezone)

The result of this function will be a time value that has time and
timezone components that are the same as the time and timezone
components of $r
.
Examples
Assume the dynamic context provides an implicit timezone of 05:00 (PT5H0M)
.
let $tz := xdt:dayTimeDuration("PT10H")

fn:adjusttimetotimezone(xs:time("10:00:00"))
returns 10:00:0005:00

fn:adjusttimetotimezone(xs:time("10:00:0007:00"))
returns 12:00:0005:00

fn:adjusttimetotimezone(xs:time("10:00:00"),
$tz)
returns 10:00:0010:00

fn:adjusttimetotimezone(xs:time("10:00:0007:00"),
$tz)
returns 07:00:0010:00

fn:adjusttimetotimezone(xs:time("10:00:00"), ())
returns 10:00:00

fn:adjusttimetotimezone(xs:time("10:00:0007:00"),
())
returns 10:00:00

fn:adjusttimetotimezone(xs:time("10:00:0007:00"),
xdt:dayTimeDuration("PT10H"))
returns 03:00:00+10:00
Arithmetic Functions on Durations, Dates and Times
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 describes an algorithm for
performing such operations.
Function
Meaning
op:subtractdateTimes
Returns the difference between two xs:dateTimes
as an xdt:dayTimeDuration
.
op:subtractdates
Returns the difference between two xs:dateTimes
as an xdt:dayTimeDuration
.
op:subtracttimes
Returns the difference between two xs:time
s as an xdt:dayTimeDuration
.
op:addyearMonthDurationtodateTime
Returns the end of a time period by adding an
xdt:yearMonthDuration
to the xs:dateTime
that starts the period.
op:adddayTimeDurationtodateTime
Returns the end of a time period by adding an
xdt:dayTimeDuration
to the xs:dateTime
that starts the period.
op:subtractyearMonthDurationfromdateTime
Returns the beginning of a time period by subtracting an
xdt:yearMonthDuration
from the xs:dateTime
that ends the period.
op:subtractdayTimeDurationfromdateTime
Returns the beginning of a time period by subtracting an
xdt:dayTimeDuration
from the xs:dateTime
that ends the period.
op:addyearMonthDurationtodate
Returns the end of a time period by adding an
xdt:yearMonthDuration
to the xs:date
that
starts the period.
op:adddayTimeDurationtodate
Returns the end of a time period by adding an
xdt:dayTimeDuration
to the xs:date
that
starts the period.
op:subtractyearMonthDurationfromdate
Returns the beginning of a time period by subtracting an
xdt:yearMonthDuration
from the xs:date
that ends the period.
op:subtractdayTimeDurationfromdate
Returns the beginning of a time period by subtracting an
xdt:dayTimeDuration
from the xs:date
that
ends the period.
op:adddayTimeDurationtotime
Adds the value of the hours, minutes and seconds components of an
xdt:dayTimeDuration
to an xs:time
value.
op:subtractdayTimeDurationfromtime
Subtracts the value of the hours, minutes and seconds components of
an xdt:dayTimeDuration
to an xs:time
value.
op:subtractdateTimes
Summary: Returns the xdt:dayTimeDuration
that corresponds to the
difference between the normalized value of $arg1
and the
normalized value of $arg2
. 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 .) is assumed to be present as
part of the value.
If the normalized value of $arg1
precedes in time the normalized
value of $arg2
, then the returned value is a negative duration.
Backs up the subtract, "", operator on xs:dateTime
values.
Examples
Assume that the dynamic context provides an implicit timezone value of 05:00
.

op:subtractdateTimes(xs:dateTime("20001030T06:12:00"),
xs:dateTime("19991128T09:00:00Z"))
returns an
xdt:dayTimeDuration
value corresponding to 337
days, 2 hours and 12 minutes.
op:subtractdates
Summary: Returns the xdt:dayTimeDuration
that corresponds to the
difference between the starting instant of $arg1
and the
the starting instant of $arg2
. 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 .) is assumed to be present as
part of the value.
The starting instant of an xs:date
is the xs:dateTime
at 00:00:00
on that date.
The result is 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.
Backs up the subtract, "", operator on xs:date
values.
Examples

Assume that the dynamic context provides an implicit timezone value of Z
. op:subtractdates(xs:date("20001030"), xs:date("19991128"))
returns an
xdt:dayTimeDuration
value corresponding to 337 days. The normalized values of the two starting instants are {2000, 10, 30, 0, 0, 0, PT0S}
and {1999, 11, 28, 0, 0, 0, PT0S}
.

If the dynamic context provides an implicit timezone value
of +05:00
,
op:subtractdates(xs:date("20001030"),
xs:date("19991128Z"))
returns an
xdt:dayTimeDuration
value corresponding to 336 days and 19 hours. The normalized values of the two starting instants are {2000, 10, 29, 19, 0, 0, PT0S}
and {1999, 11, 28, 0, 0, 0, PT0S}
.

op:subtractdates(xs:date("2000101505:00"),
xs:date("20001010+02:00"))
returns an
xdt:dayTimeDuration
value corresponding to lexical form "P5DT7H
".
op:subtracttimes
Summary: Returns the xdt:dayTimeDuration
that corresponds to the
difference between the value of $arg1
converted to an xs:dateTime
using the date components from the reference xs:dateTime
and the
value of $arg2
converted to an xs:dateTime
using the date components from the same reference xs:dateTime
. 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 .) is assumed to be present as
part of the value.
The result is the result of subtracting the two xs:dateTime
s using
op:subtractdateTimes
.
If the value of $arg1
converted to an xs:dateTime
using the date components from the reference xs:dateTime
precedes in time the
value of $arg2
converted to an xs:dateTime
using the date components from the same reference xs:dateTime
, then the returned value is a negative duration.
Backs up the subtract, "", operator on xs:time
values.
Examples
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"
.

op:subtracttimes(xs:time("11:12:00Z"),
xs:time("04:00:00"))
returns an
xdt:dayTimeDuration
value corresponding to 2 hours
and 12 minutes. This is obtained by subtracting from the xs:dateTime
value {1972, 12, 31, 11, 12, 0, PT0S}
the xs:dateTime
value {1972, 12, 31, 9, 0, 0, PT0S}
.

op:subtracttimes(xs:time("11:00:0005:00"),
xs:time("21:30:00+05:30"))
returns a zero
xdt:dayTimeDuration
value corresponding to the lexical representation "PT0S"
. The two 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}
.

op:subtracttimes(xs:time("17:00:0006:00"),
xs:time("08:00:00+09:00"))
returns an
xdt:dayTimeDuration
value corresponding to one day or 24 hours. The two normalized xs:dateTime
values are {1972, 12, 31, 23, 0, 0, PT0S}
and {1972, 12, 30, 23, 0, 0, PT0S}
.

op:subtracttimes(xs:time("24:00:00"), xs:time("23:59:59"))
returns an
xdt:dayTimeDuration
value corresponding to "PT23H59M59S"
. The two normalized xs:dateTime
values are {1972, 12, 31, 0, 0, 0, ()}
and {1972, 12, 31, 23, 59, 59.0, ()}
.
op:addyearMonthDurationtodateTime
Summary: Returns the xs:dateTime
computed by adding
$arg2
to the value of $arg1
using the
algorithm described in Appendix E of disregarding the rule about leap seconds. If
$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.
This functions backs up the "+" operator on xs:dateTime
and
xdt:yearMonthDuration
values.
Examples

op:addyearMonthDurationtodateTime(xs:dateTime("20001030T11:12:00"),
xdt:yearMonthDuration("P1Y2M"))
returns an
xs:dateTime
value corresponding to the lexical
representation "20011230T11:12:00"
.
op:adddayTimeDurationtodateTime
Summary: Returns the xs:dateTime
computed by adding
$arg2
to the value of $arg1
using the
algorithm described in Appendix E of disregarding the rule about leap seconds. If
$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.
This functions backs up the "+" operator on xs:dateTime
and
xdt:dayTimeDuration
values.
Examples

op:adddayTimeDurationtodateTime(xs:dateTime("20001030T11:12:00"),
xdt:dayTimeDuration("P3DT1H15M"))
returns an
xs:dateTime
value corresponding to the lexical
representation "20001102T12:27:00"
.
op:subtractyearMonthDurationfromdateTime
Summary: Returns the xs:dateTime
computed by negating
$arg2
and adding the result to the value of
$arg1
using the algorithm described in Appendix E of disregarding the rule about leap seconds. If $arg2
is negative, then the
xs:dateTime
returned follows $arg1
.
The result has the same timezone as $arg1
. If $arg1
has no timezone, the result has no timezone.
This functions backs up the "" operator on xs:dateTime
and
xdt:yearMonthDuration
values.
Examples

op:subtractyearMonthDurationfromdateTime(xs:dateTime("20001030T11:12:00"),
xdt:yearMonthDuration("P1Y2M"))
returns an
xs:dateTime
value corresponding to the lexical
representation "19990830T11:12:00"
.
op:subtractdayTimeDurationfromdateTime
Summary: Returns the xs:dateTime
computed by negating
$arg2
and adding the result to the value of
$arg1
using the algorithm described in Appendix E of disregarding the rule about leap seconds. If $arg2
is negative, then the
xs:dateTime
returned follows $arg1
.
The result has the same timezone as $arg1
. If $arg1
has no timezone, the result has no timezone.
This functions backs up the "" operator on xs:dateTime
and
xdt:dayTimeDuration
values.
Examples

op:subtractdayTimeDurationfromdateTime(xs:dateTime("20001030T11:12:00"),
xdt:dayTimeDuration("P3DT1H15M"))
returns an
xs:dateTime
value corresponding to the lexical
representation "20001027T09:57:00"
.
op:addyearMonthDurationtodate
Summary: Returns the xs:date
computed by adding
$arg2
to the starting instant of $arg1
using the
algorithm described in Appendix E of and discarding the time components from the resulting xs:dateTime
. If
$arg2
is negative, then the xs:date
returned
precedes $arg1
.
The starting instant of an xs:date
is the xs:dateTime
at time 00:00:00
on that date.
The result has the same timezone as $arg1
. If $arg1
has no timezone, the result has no timezone.
This functions backs up the "+" operator on xs:date
and
xdt:yearMonthDuration
values.
Examples

op:addyearMonthDurationtodate(xs:date("20001030"),
xdt:yearMonthDuration("P1Y2M"))
returns
the xs:date
corresponding to December 30, 2001.
op:adddayTimeDurationtodate
Summary: Returns the xs:date
computed by adding
$arg2
to the starting instant of $arg1
using the
algorithm described in Appendix E of and discarding the time components from the resulting xs:dateTime
. If
$arg2
is negative, then the xs:date
returned
precedes $arg1
.
The starting instant of an xs:date
is the xs:dateTime
at time 00:00:00
on that date.
The result has the same timezone as $arg1
. If $arg1
has no timezone, the result has no timezone.
This functions backs up the "+" operator on xs:date
and
xdt:dayTimeDuration
values.
Examples

op:adddayTimeDurationtodate(xs:date("20041030Z"),
xdt:dayTimeDuration("P2DT2H30M0S"))
returns the
xs:date
November 1, 2004. The starting instant of the first argument is the 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.
op:subtractyearMonthDurationfromdate
Summary: Returns the xs:date
computed by negating
$arg2
and adding the result to the starting instant of
$arg1
using the algorithm described in Appendix E of and discarding the time components from the resulting xs:dateTime
. If $arg2
is positive, then the
xs:date
returned precedes $arg1
.
The starting instant of an xs:date
is the xs:dateTime
at 00:00:00
on that date.
The result has the same timezone as $arg1
. If $arg1
has no timezone, the result has no timezone.
This functions backs up the "" operator on xs:date
and
xdt:yearMonthDuration
values.
Examples

op:subtractyearMonthDurationfromdate(xs:date("20001030"),
xdt:yearMonthDuration("P1Y2M"))
returns the
xs:date
August 30, 1999.

op:subtractyearMonthDurationfromdate(xs:date("20000229Z"),
xdt:yearMonthDuration("P1Y"))
returns the
xs:date
February 28,
1999 in timezone Z
.

op:subtractyearMonthDurationfromdate(xs:date("2000103105:00"),
xdt:yearMonthDuration("P1Y1M"))
returns the
xs:date
September 30,
1999 in timezone 05:00
.
op:subtractdayTimeDurationfromdate
Summary: Returns the xs:date
computed by negating
$arg2
and adding the result to the starting instant of
$arg1
using the algorithm described in Appendix E of and discarding the time components from the resulting xs:dateTime
. If $arg2
is positive, then the
xs:date
returned precedes $arg1
.
The starting instant of an xs:date
is the xs:dateTime
at 00:00:00
on that date.
The result has the same timezone as $arg1
. If $arg1
has no timezone, the result has no timezone.
This functions backs up the "" operator on xs:date
and
xdt:dayTimeDuration
values.
Examples

op:subtractdayTimeDurationfromdate(xs:date("20001030"),
xdt:dayTimeDuration("P3DT1H15M"))
returns the
xs:date
October 26, 2000.
op:adddayTimeDurationtotime
Summary: First, the days component in the canonical lexical representation of
$arg2
is set to zero (0) and the value of the resulting
xdt: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 components of the result 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.
This functions backs up the "+" operator on xs:time
and
xdt:dayTimeDuration
values.
Examples

op:adddayTimeDurationtotime(xs:time("11:12:00"),
xdt:dayTimeDuration("P3DT1H15M"))
returns the
xs:time
value corresponding to the lexical
representation "12:27:00
".

op:adddayTimeDurationtotime(xs:time("23:12:00+03:00"),
xdt:dayTimeDuration("P1DT3H15M"))
returns the
xs:time
value corresponding to the lexical
representation "02:27:00+03:00
", i.e. {0, 0, 0, 2, 27, 0, PT3H}
.
op:subtractdayTimeDurationfromtime
Summary: The result is calculated by first setting the day component in the
canonical lexical representation of $arg2
to zero (0) and
calculating the value of the resulting xdt:dayTimeDuration
.
Alternatively, the value of $arg2
modulus 86,400 is used as the second argument. This
value is subtracted from the value of $arg1
converted to an xs:dateTime
using a reference date such as 19721231
and the time components of the
result are returned. Note that the xs:time
returned may occur in
a preceding or following day and may be greater than $arg1
.
The result has the same timezone as $arg1
. If $arg1
has no timezone, the result has no timezone.
This functions backs up the "" operator on xs:time
and
xdt:dayTimeDuration
values.
Examples

op:subtractdayTimeDurationfromtime(xs:time("11:12:00"),
xdt:dayTimeDuration("P3DT1H15M"))
returns an
xs:time
value corresponding to the lexical
representation "09:57:00"
.

op:subtractdayTimeDurationfromtime(xs:time("08:20:0005:00"),
xdt:dayTimeDuration("P23DT10H10M"))
returns the
xs:time
value corresponding to the lexical
representation "22:10:0005:00"
i.e. {0, 0, 0, 22, 10, 0, PT5H}
Functions Related to QNames
Additional Constructor Functions for QNames
This section
defines additional constructor functions for QName as defined in . Leading and trailing whitespace, if present, is stripped from
string arguments before the result is constructed.
Function
Meaning
fn:resolveQName
Returns an xs:QName
with the lexical form given in the
first argument. The prefix is resolved using the inscope namespaces
for a given element.
fn:QName
Returns an xs:QName
with the namespace URI given in the
first argument and the local name and prefix in the second argument.
fn:resolveQName
Summary: 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.
If $qname
does not have the correct lexical form
for xs:QName
an error is raised .
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 a prefix and if there is no namespace binding
for $element
that matches this prefix, then an error is raised
.
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 $qname
argument is retained in the returned expandedQName, as discussed in
.
Usage Note
Sometimes the requirement is to construct an xs:QName
without using the default namespace. This can be achieved by writing:
if (contains($qname, ":")) then fn:resolveQName($qname, $element) else
fn:QName("", $qname)
If the requirement is to construct an xs:QName
using the
namespaces in the static context, then the xs:QName
constructor should be used.
Examples
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".
fn:QName
Summary: Returns an xs:QName
with the namespace URI given in
$paramURI
. If $paramURI
is the zerolength string or the
empty sequence, it represents "no namespace"; in this case, if the value
of $paramQName
contains a colon (:
),
an error is raised .
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
.
If $paramQName
does not have the correct lexical form
for
xs:QName
an error is raised .
Note that unlike xs:QName
this function does not require
a xs:string
literal as the argument.
Examples

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".
Operators and Functions Related to QNames
This section discusses functions on QNames as defined in .
Function
Meaning
op:QNameequal
Returns true
if the local names and namespace URIs of
the two arguments are equal.
fn:prefixfromQName
Returns an xs:NCName
representing the prefix of the
xs:QName
argument.
fn:localnamefromQName
Returns an xs:NCName
representing the local name of the
xs:QName
argument.
fn:namespaceurifromQName
Returns the namespace URI for the xs:QName
argument. If
the xs:QName
is in no namespace, the zerolength string
is returned.
fn:namespaceuriforprefix
Returns the namespace URI of one of the inscope namespaces for the
given element, identified by its namespace prefix.
fn:inscopeprefixes
Returns the prefixes of the inscope namespaces for the given
element.
op:QNameequal
Summary: Returns true
if the namespace URIs of
$arg1
and $arg2
are equal and the local names of
$arg1
and $arg2
are identical based on the default
collation. Otherwise, returns false
. Two namespace URIs are
considered equal if they are either both absent or both present and
identical based on the Unicode code point
collation (http://www.w3.org/2005/xpathfunctions/collation/codepoint
). The prefix parts of
$arg1
and $arg2
, if any, are ignored.
Backs up the "eq" and "ne" operators on values of type xs:QName
.
fn:prefixfromQName
Summary: Returns an xs:NCName
representing the prefix of
$arg
. The empty sequence is returned if $arg
is the empty sequence or if the value of $arg
contains no prefix.
fn:localnamefromQName
Summary: Returns an xs:NCName
representing the local part of
$arg
. If $arg
is the empty sequence, returns the
empty sequence.
Examples

fn:localnamefromQName(fn:QName("http://www.example.com/example",
"person"))
returns "person"
.
fn:namespaceurifromQName
Summary: Returns the namespace URI for $arg
as an
xs:string
. If $arg
is the empty sequence, the
empty sequence is returned. If $arg
is in no namespace, the
zerolength string is returned.
Examples

fn:namespaceurifromQName(fn:QName("http://www.example.com/example",
"person"))
returns the namespace URI corresponding to
"http://www.example.com/example"
.
fn:namespaceuriforprefix
Summary: Returns the namespace URI of one of the inscope namespaces for
$element
, identified by its namespace prefix.
If $element
has an inscope namespace whose namespace prefix is
equal to $prefix
, it returns the namespace URI of that
namespace. If $prefix
is the zerolength string or the empty sequence, it returns the
namespace URI of the default (unnamed) namespace. Otherwise, it returns the
empty sequence.
Prefixes are equal only if their Unicode code points match exactly.
fn:inscopeprefixes
Summary: Returns the prefixes of the inscope namespaces for
$element
. For namespaces that have a prefix, it returns the
prefix as an xs:NCName
. For the default namespace, which has no
prefix, it returns the zerolength string.
Functions and Operators on base64Binary and hexBinary
Comparisons of base64Binary and hexBinary Values
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 the two arguments are equal.
op:base64Binaryequal
Returns true
if the two arguments are equal.
op:hexBinaryequal
Summary: 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, returns
false
.
This function backs up the "eq" and "ne" operators on
xs:hexBinary
values.
op:base64Binaryequal
Summary: 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, returns false
.
This function backs up the "eq" and "ne" operators on
xs:base64Binary
values.
Functions and Operators on NOTATION
Operators on NOTATION
This section discusses functions that take NOTATION as arguments.
Function
Meaning
op:NOTATIONequal
Returns true
if the two arguments are equal.
op:NOTATIONequal
Summary: Returns true
if $arg1
and
$arg2
compare equal on a codepointbycodepoint basis. Else
returns false
. This function backs up the "eq" and "ne"
operators on xs:NOTATION
values.
Functions and Operators on Nodes
This section discusses functions and operators on nodes. Nodes are formally defined
in .
Function
Meaning
fn:name
Returns the name of the context node or the specified node as an
xs:string
.
fn:localname
Returns the local name of the context node or the specified node as an
xs:NCName
.
fn:namespaceuri
Returns the namespace URI as an xs:anyURI
for the
xs:QName
of the argument node or the context node if the
argument is omitted. This may be the URI corresponding to the
zerolength string if the xs:QName
is in no namespace.
fn:number
Returns the value of the context item after atomization or the specified
argument converted to an xs:double
.
fn:lang
Returns true
or false
, depending on whether the
language of the given node or the context node, as defined using the
xml:lang attribute, is the same as, or a sublanguage of, the language
specified by the argument.
op:issamenode
Returns true
if the two arguments have the same identity.
op:nodebefore
Indicates whether one node appears before another node in document
order.
op:nodeafter
Indicates whether one node appears after another node in document order.
fn:root
Returns the root of the tree to which the node argument belongs.
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
, $item2
, etc. are
each bound to single lineitem element nodes in the document in sequence and that
the value of the quantity child of the first lineitem is 5.0
.
<PurchaseOrder>
<lineitem>
<description> ... </description>
<price> ... </price>
<quantity>5.0</quantity>
...
</lineitem>
<lineitem>
...
</lineitem>
...
</PurchaseOrder>
fn:name
Summary: Returns the name of a node, as an xs:string
that is either
the zerolength string, or has the lexical form of an xs:QName
.
If the argument is omitted, it defaults to the context node. If the context item
is undefined an error is raised: . If the
context item is not a node an error is raised: .
If the argument is supplied and is the empty sequence, the function returns the
zerolength string.
If the target node has no name (that is, if it is a document node, a comment, a
text node, or a namespace binding having no name), the function returns the
zerolength string.
Otherwise, the value returned is fn:string(fn:nodename($arg))
.
fn:localname
Summary: Returns the local part of the name of $arg
as an
xs:string
that will either be the zerolength string or will have
the lexical form of an xs:NCName
.
If the argument is omitted, it defaults to the context node. If the context item
is undefined an error is raised: . If the
context item is not a node an error is raised .
If the argument is supplied and is the empty sequence, the function returns the
zerolength string.
If the target node has no name (that is, if it is a document node, a comment, or
a text node), the function returns the zerolength string.
Otherwise, the value returned will be the local part of the expandedQName of the
target node (as determined by the dm:nodename
accessor in . This will be an xs:string
whose
lexical form is an xs:NCName
.
fn:namespaceuri
Summary: Returns the namespace URI of the xs:QName
of $arg
.
If the argument is omitted, it defaults to the context node. If the context item
is undefined an error is raised: . If the
context item is not a node an error is raised .
If $arg
is the empty sequence, the xs:anyURI
corresponding to the zerolength string is returned.
If $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 ) is in no namespace, then the function returns the
xs:anyURI
corresponding to the zerolength string.
fn:number
Summary: Returns the value indicated by $arg
or, if
$arg
is not specified, the context item after atomization,
converted to an xs:double
. If $arg
is the empty
sequence or if $arg
or the context item cannot be converted to an
xs:double
, the xs:double
value NaN
is
returned. If the context item is undefined an error is raised: .
Calling the zeroargument version of the function is defined to give the same
result as calling the singleargument version with an argument of ".". That is,
fn:number()
is equivalent to fn:number(.)
.
If $arg
is the empty sequence, NaN
is returned.
Otherwise, $arg
, or the context item after atomization, is
converted to an xs:double
following the rules of . If the conversion to xs:double
fails,
the xs:double
value NaN
is returned.
Examples

fn:number($item1/quantity)
returns 5.0
.

fn:number($item2)
returns NaN
.

Assume that the context item is the xs:string
"15
". fn:number()
returns 1.5E1
.
fn:lang
Summary: This function tests whether the language of $node
, or the
context node 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 language of the argument node,
or the context node 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 the second argument is omitted and the context item is undefined an error is
raised: . If the context item is not a node an
error is raised .
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:
(ancestororself::*/@xml:lang)[last()]
If this expression returns an empty sequence, the function returns
false
.
Otherwise, the function returns true
if and only if the stringvalue
of the relevant xml:lang
attribute is equal
to $testlang
based on a caseless default match as specified in
section 3.13 of , or if the stringvalue of the relevant
testlang
attribute contains a hyphen, "" (The character "" is
HYPHENMINUS, #x002D) such that the part of the stringvalue preceding that
hyphen is equal to $testlang
, using caseless matching.
Examples

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"/>
op:issamenode
Summary: If the node identified by the value of $parameter1
is the
same node as the node identified by the value of $parameter2
(that
is, the two nodes have the same identity), then the function returns
true
; otherwise, the function returns false
. This
function backs up the "is" operator on nodes.
Examples

op:issamenode($item1, $item1)
returns
true
.

op:issamenode($item1, $item2)
returns
false
.
op:nodebefore
Summary: If the node identified by the value of $parameter1
occurs
in document order before the node identified by the value of
$parameter2
, this 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 . This function backs up the "<<" operator.
Examples

op:nodebefore($item1, $item2)
returns
true
.

op:nodebefore($item1, $item1)
returns
false
.
op:nodeafter
Summary: If the node identified by the value of $parameter1
occurs
in document order after the node identified by the value of
$parameter2
, this 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 . This function backs up the ">>" operator.
Examples

op:nodeafter($item1, $item2)
returns
false
.

op:nodeafter($item1, $item1)
returns
false
.

op:nodeafter($item2, $item1)
returns
true
.
fn:root
Summary: Returns the root of the tree to which $arg
belongs. This
will usually, but not necessarily, be a document node.
If $arg
is the empty sequence, the empty sequence is returned.
If $arg
is a document node, $arg
is returned.
If the function is called without an argument, the context item is used as the
default argument. If the context item is undefined an error is raised: . If the context item is not a node an error is
raised: .
Examples
These examples use some variables which could be defined in as:
let $i := <tool>wrench</tool>
let $o := <order> {$i} <quantity>5</quantity> </order>
let $odoc := document {$o}
let $newi := $o/tool
Or they could be defined in as:
<xsl:variable name="i" as="element()">
<tool>wrench</tool>
</xsl:variable>
<xsl:variable name="o" as="element()">
<order>
<xsl:copyof select="$i"/>
<quantity>5</quantity>
</order>
</xsl:variable>
<xsl:variable name="odoc">
<xsl:copyof select="$o"/>
</xsl:variable>
<xsl:variable name="newi" select="$o/tool"/>

fn:root($i)
returns $i

fn:root($o/quantity)
returns $o

fn:root($odoc//quantity)
returns $odoc

fn:root($newi)
returns $o
The final three examples could be made typesafe by wrapping their operands with fn:exactlyone().
Functions and Operators on Sequences
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 and .
General Functions and Operators on Sequences
The following functions are defined on sequences.
Function
Meaning
fn:boolean
Computes the effective boolean value of the argument sequence.
op:concatenate
Concatenates two sequences.
fn:indexof
Returns a sequence of xs:integer
s, each of which is the
index of a member of the sequence specified as the first argument
that is equal to the value of the second argument. If no members of
the specified sequence are equal to the value of the second
argument, the empty sequence is returned.
fn:empty
Indicates whether or not the provided sequence is empty.
fn:exists
Indicates whether or not the provided sequence is not empty.
fn:distinctvalues
Returns a sequence in which all but one of a set of duplicate
values, based on value equality, have been deleted. The order in
which the distinct values are returned is .
fn:insertbefore
Inserts an item or sequence of items at a specified position in a
sequence.
fn:remove
Removes an item from a specified position in a sequence.
fn:reverse
Reverses the order of items in a sequence.
fn:subsequence
Returns the subsequence of a given sequence, identified by location.
fn:unordered
Returns the items in the given sequence in a nondeterministic
order.
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.
fn:boolean
Summary: Computes the effective boolean value of the sequence
$arg
. See
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
or xdt: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 .
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
returns false
.
Examples
let $x := ("a", "b", "c")

fn:boolean($x)
raises a type error .

fn:boolean($x[1])
returns true
.

fn:boolean($x[0])
returns false
.
op:concatenate
Summary: Returns a sequence consisting of the items in $seq1
followed by the items in $seq2
. This function backs up the
infix operator ",". If either sequence is the empty sequence, the other
operand is returned.
For detailed type semantics, see
Examples

op:concatenate((1, 2, 3), (4, 5))
returns (1,
2, 3, 4, 5)
.

op:concatenate((1, 2, 3), ())
returns (1, 2,
3)
.

op:concatenate((), ())
returns ()
.
fn:indexof
Summary: Returns a sequence of positive integers giving the positions within
the sequence $seqParam
of items that are equal to $srchParam
.
The collation used by the invocation of this function is determined according
to the rules in . The collation is used when
string comparison is required.
The items in the sequence $seqParam
are compared with
$srchParam
under the rules for the eq
operator.
Values that cannot be compared, i.e. 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
$srchParam
is included in the result.
If the value of $seqParam
is the empty sequence, or if no item
in $seqParam
matches $srchParam
, then the empty
sequence is returned.
The first item in a sequence is at position 1, not position 0.
The result sequence is in ascending numeric order.
Examples

fn:indexof ((10, 20, 30, 40), 35)
returns ().

fn:indexof ((10, 20, 30, 30, 20, 10), 20)
returns
(2, 5).

fn:indexof (("a", "sport", "and", "a", "pastime"),
"a")
returns (1, 4).

If @a is an attribute of type xs:NMTOKENS
whose
typed value is
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
s.
fn:empty
Summary: If the value of $arg
is the empty sequence, the
function returns true
; otherwise, the function returns
false
.
Examples

fn:empty(fn:remove(("hello", "world"), 1))
returns
false
.
fn:exists
Summary: If the value of $arg
is not the empty sequence, the
function returns true
; otherwise, the function returns
false
.
Examples

fn:exists(fn:remove(("hello"), 1))
returns
false
.
fn:distinctvalues
Summary: Returns the sequence that results from removing
from $arg
all but one of a set of values that are eq
to one other. Values that cannot be compared, i.e. the eq
operator is not defined for their types, are considered to be distinct.
Values of type xdt:untypedAtomic
are compared as if they were of
type xs:string
. The order in which the sequence of values is
returned is .
The static type of the result is a sequence of prime types as defined in
.
The collation used by the invocation of this function is determined according
to the rules in . The collation is used when
string comparison is required.
If $arg
is the empty sequence, the empty sequence is returned.
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.
Which value of a set of values that compare equal is returned is .
Examples

fn:distinctvalues((1, 2.0, 3, 2))
might return
(1, 3, 2.0)
.

The following query:
let $x as xdt:untypedAtomic*
:= (xdt:untypedAtomic("cherry"),
xdt:untypedAtomic("bar"),
xdt:untypedAtomic("bar"))
return fn:distinctvalues ($x)
returns a sequence containing two items of type
xdt:untypedAtomic
.
fn:insertbefore
Summary: Returns a new sequence constructed from the value of
$target
with the value of $inserts
inserted at the
position specified by the value of $position
. (The value of
$target
is not affected by the sequence construction.)
If $target
is the empty sequence, $inserts
is
returned. If $inserts
is the empty sequence,
$target
is returned.
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 sequence.
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.
For detailed semantics see, .
Examples
let $x
:= ("a", "b", "c")

fn:insertbefore($x, 0, "z")
returns ("z",
"a", "b", "c")

fn:insertbefore($x, 1, "z")
returns ("z",
"a", "b", "c")

fn:insertbefore($x, 2, "z")
returns ("a",
"z", "b", "c")

fn:insertbefore($x, 3, "z")
returns ("a",
"b", "z", "c")

fn:insertbefore($x, 4, "z")
returns ("a",
"b", "c", "z")
fn:remove
Summary: Returns a new sequence constructed from the value of
$target
with the item at the position specified by the value of
$position
removed.
If $position
is less than 1 or greater than the number of items
in $target
, $target
is returned. Otherwise, the
value returned by the function consists of all items of $target
whose index is less than $position
, followed by all items of
$target
whose index is greater than $position
. If
$target
is the empty sequence, the empty sequence is returned.
For detailed type semantics, see
Examples
let $x
:= ("a", "b", "c")

fn:remove($x, 0)
returns ("a", "b", "c")

fn:remove($x, 1)
returns ("b", "c")

fn:remove($x, 6)
returns ("a", "b", "c")

fn:remove((), 3)
returns ()
fn:reverse
Summary: Reverses the order of items in a sequence. If $arg
is
the empty sequence, the empty sequence is returned.
For detailed type semantics, see
Examples
let $x
:= ("a", "b", "c")

fn:reverse($x)
returns ("c", "b", "a")

fn:reverse(("hello"))
returns ("hello")

fn:reverse(())
returns ()
fn:subsequence
Summary: 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
.
In the twoargument case, returns:
$sourceSeq[fn:round($startingLoc) le $p] In the threeargument case, returns:
$sourceSeq[fn:round($startingLoc) le $p
and $p lt fn:round($startingLoc) + fn:round($length)]
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
.
The first item of a sequence is located at position 1, not position 0.
For detailed type semantics, see .
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.
Examples
Assume $seq = ($item1, $item2, $item3, $item4, ...)

fn:subsequence($seq, 4)
returns ($item4, ...)

fn:subsequence($seq, 3, 2)
returns ($item3, $item4)
fn:unordered
Summary: Returns the items of $sourceSeq
in an order.
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.
Functions That Test the Cardinality of Sequences
The following functions test the cardinality of their sequence arguments.
Function
Meaning
fn:zeroorone
Returns the input sequence if it contains zero or one items. Raises
an error otherwise.
fn:oneormore
Returns the input sequence if it contains one or more items. Raises
an error otherwise.
fn:exactlyone
Returns the input sequence if it contains exactly one item. Raises
an error otherwise.
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 XML Schema describing
the output of a query may require a sequence of length oneormore in some
position, but the static type system may not be able to infer this; inserting a
call to fn:oneormore
at the appropriate place will provide a
suitable static type at query analysis time, and confirm that the length is
correct with a dynamic check at query execution time.
fn:zeroorone
Summary: Returns $arg
if it contains zero or one items.
Otherwise, raises an error .
For detailed type semantics, see
fn:oneormore
Summary: Returns $arg
if it contains one or more items.
Otherwise, raises an error .
For detailed type semantics, see
fn:exactlyone
Summary: Returns $arg
if it contains exactly one item. Otherwise,
raises an error .
For detailed type semantics, see
Equals, Union, Intersection and Except
Function
Meaning
fn:deepequal
Returns true
if the two arguments have items that
compare equal in corresponding positions.
op:union
Returns the union of the two sequence arguments, eliminating
duplicates.
op:intersect
Returns the intersection of the two sequence arguments, eliminating
duplicates.
op:except
Returns the difference of the two sequence arguments, eliminating
duplicates.
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.
fn:deepequal
Summary: 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. This is defined in more detail below. 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 a node, 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))
.

the two nodes are both annotated as having simple content or both nodes are annotated as having complex 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 have a type annotation that is simple content, and the
typed value of $i1
is deepequal to the typed
value of $i2
.

Both element nodes have a type annotation that
is complex content with elementOnly content, and each child element of $i1
is deepequal to the corresponding child element of $i2
.

Both element nodes have a type annotation that
is complex content with mixed content, and the sequence $i1/(*text())
is
deepequal to the sequence $i2/(*text())
.

Both element nodes have a type annotation that
is complex content with empty content.
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 or namespace bindings,
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 string value of $i1
is equal to the string value of $i2
.
If the two nodes are both text nodes or comment nodes, then they are
deepequal if and only if their stringvalues are equal.
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 and ). The order of
children is significant, but the order of attributes is insignificant.
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.
Examples
let $at := <attendees> <name last='Parker'
first='Peter'/> <name last='Barker' first='Bob'/>
<name last='Parker' first='Peter'/> </attendees>

fn:deepequal($at, $at/*)
returns false
.

fn:deepequal($at/name[1], $at/name[2])
returns false
.

fn:deepequal($at/name[1], $at/name[3])
returns true
.

fn:deepequal($at/name[1], 'Peter Parker')
returns false
.
op:union
Summary: Constructs a sequence containing every node that occurs in the
values of either $parameter1
or $parameter2
,
eliminating duplicate nodes. Nodes are returned in document order. Two nodes
are duplicates if they are op:issamenode()
.
If either operand is the empty sequence, a sequence is returned containing
the nodes in the other operand in document order after eliminating duplicates.
For detailed type semantics, see
This function backs up the "union" or "" operator.
Examples
Assume $seq1 = ($item1, $item2), $seq2 = ($item1, $item2)
and $seq3 = ($item2, $item3)
.

op:union($seq1, $seq1)
returns the sequence
($item1, $item2)
.

op:union($seq2, $seq3)
returns the sequence
consisting of ($item1, $item2, $item3)
.
op:intersect
Summary: Constructs a sequence containing every node that occurs in the
values of both $parameter1
and $parameter2
,
eliminating duplicate nodes. Nodes are returned in document order.
If either operand is the empty sequence, the empty sequence is returned.
Two nodes are duplicates if they are op:issamenode()
.
For detailed type semantics, see .
This function backs up the "intersect" operator.
Examples
Assume $seq1 = ($item1, $item2), $seq2 = ($item1, $item2)
and $seq3 = ($item2, $item3)
.

op:intersect($seq1, $seq1)
returns the sequence
($item1, $item2)
.

op:intersect($seq2, $seq3)
returns the sequence
($item2)
.
op:except
Summary: Constructs a sequence containing every node that occurs in the value
of $parameter1
, but not in the value of
$parameter2
, eliminating duplicate nodes. Nodes are returned in
document order.
If $parameter1
is the empty sequence, the empty sequence is
returned. If $parameter2
is the empty sequence, a sequence is
returned containing the nodes in $parameter1
in document order
after eliminating duplicates.
Two nodes are duplicates if they are op:issamenode()
.
For detailed type semantics, see .
This function backs up the "except" operator.
Examples
Assume $seq1 = ($item1, $item2), $seq2 = ($item1, $item2)
and $seq3 = ($item2, $item3)
.

op:except($seq1, $seq2)
returns the empty sequence.

op:except($seq2, $seq3)
returns the sequence
($item1)
.
Aggregate Functions
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. xdt: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 a sequence of values.
fn:max
Returns the maximum value from a sequence of comparable values.
fn:min
Returns the minimum value from a sequence of comparable values.
fn:sum
Returns the sum of a sequence of values.
fn:count
Summary: Returns the number of items in the value of $arg
.
Returns 0 if $arg
is the empty sequence.
Examples
Assume $seq1 = ($item1, $item2)
and $seq3 = ()
,
the empty sequence.

fn:count($seq1)
returns 2
.

fn:count($seq3)
returns 0
.
Assume $seq2 = (98.5, 98.3, 98.9)
.

fn:count($seq2)
returns 3
.

fn:count($seq2[. > 100])
returns 0
.
fn:avg
Summary: Returns the average of the values in the input
sequence $arg
, that is, the sum of the values divided by the
number of values.
If $arg
is the empty sequence, the empty sequence is returned.
If $arg
contains values of type xdt:untypedAtomic
they are cast to xs:double
.
Duration values must either all be xdt:yearMonthDuration
values
or must all be xdt:dayTimeDuration
values. For numeric values,
the numeric promotion rules defined in are used
to promote all values to a single common type. After these operations,
$arg
must contain items of a single type, which must be one of
the four numeric types, xdt:yearMonthDuration
or
xdt:dayTimeDuration
or one if its subtypes.
If the above conditions are not met, then a type error is raised .
Otherwise, returns the average of the values computed as sum($arg) div
count($arg)
.
For detailed type semantics, see .
Examples
Assume $d1 = xdt:yearMonthDuration("P20Y")
and $d2 =
xdt:yearMonthDuration("P10M")
and $seq3 = (3, 4, 5)
.

fn:avg($seq3)
returns 4.0
.

fn:avg(($d1, $d2))
returns a
yearMonthDuration
with value 125
months.

fn:avg(($d1, $seq3))
raises a type error .

fn:avg(())
returns ()
.

fn:avg((xs:float('INF')), xs:float('INF'))
returns
NaN
.

fn:avg(($seq3, xs:float('NaN'))
returns
NaN
.
fn:max
Summary: Selects an item from the input sequence $arg
whose
value is greater than or equal to the value of every other item in the input
sequence. If there are two or more such items, then the specific item whose
value is returned is .
The following rules are applied to the input sequence:
Values of type xdt:untypedAtomic
in $arg
are cast to xs:double
.
For numeric values,
the numeric promotion rules defined in are used
to promote all values to a single common type.
The items in the
resulting sequence may be reordered in an arbitrary order. The resulting
sequence is referred to below as the converted sequence. This 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 $arg
must be numeric or derived from a single base
type for which the ge
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 purposes of comparison. Duration values
must either all be xdt:yearMonthDuration
values or must all be
xdt:dayTimeDuration
values.
If any of these conditions is not met, then a type error is raised .
If the converted sequence contains the value NaN
, the value
NaN
is returned.
If the items in the value of $arg
are of type
xs:string
or types derived by restriction from
xs:string
, then the determination of the item with the largest
value is made according to the collation that is used. If the type of the
items in $arg
is not xs:string
and
$collation
is specified, the collation is ignored.
The collation used by the invocation of this function is determined according
to the rules in .
Otherwise, the result of the function is the result of the expression:
if (every $v in $c satisfies $c[1] ge $v)
then $c[1]
else fn:max(fn:subsequence($c, 2))
evaluated with $collation
as the default collation if specified, and with $c
as the converted sequence.
For detailed type semantics, see .
If the converted sequence contains exactly one value then that value is returned.
The default type when the fn:max
function is applied
to xdt: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
.
Examples

fn:max((3,4,5))
returns 5
.

fn:max((5, 5.0e0))
returns 5.0e0
.

fn:max((3,4,"Zero"))
raises a type error .

fn:max((fn:currentdate(), xs:date("20010101")))
typically returns the current date.

fn:max(("a", "b", "c"))
returns "c" under a typical
default collation.
fn:min
Summary: selects an item from the input sequence $arg
whose
value is less than or equal to the value of every other item in the input
sequence. If there are two or more such items, then the specific item whose
value is returned is .
The following rules are applied to the input sequence:
Values of type xdt:untypedAtomic
in $arg
are cast to xs:double
.
For numeric values,
the numeric promotion rules defined in are used
to promote all values to a single common type.
The items in the
resulting sequence may be reordered in an arbitrary order. The resulting
sequence is referred to below as the converted sequence. This 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 $arg
must be numeric or derived from a single base
type for which 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 xdt:yearMonthDuration
values or must all be
xdt:dayTimeDuration
values.
If any of these conditions is not met, a type error is raised .
If the converted sequence contains the value NaN
, the value
NaN
is returned.
If the items in the value of $arg
are of type
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 $arg
is not xs:string
and
$collation
is specified, the collation is ignored.
The collation used by the invocation of this function is determined according
to the rules in .
Otherwise, the result of the function is the result of the expression:
if (every $v in $c satisfies $c[1] le $v)
then $c[1]
else fn:min(fn:subsequence($c, 2))
evaluated with $collation
as the default collation if specified, and with $c
as the converted sequence.
For detailed type semantics, see .
If the converted sequence contains exactly one value then that value is returned.
The default type when the fn:min
function is applied
to xdt: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
.
Examples

fn:min((3,4,5))
returns 3
.

fn:min((5, 5.0e0))
returns 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. does not distinguish between the values positive zero and negative zero. The result is .

fn:min((fn:currentdate(), xs:date("20010101")))
typically returns xs:date("20010101")
.

fn:min(("a", "b", "c"))
returns "a" under a typical
default collation.
fn:sum
Summary: Returns a value obtained by adding together the values
in $arg
. If $zero
is not specified, then the value
returned for an empty sequence is the xs:integer
value 0. If
$zero
is specified, then the value returned for an empty
sequence is $zero.
.
Any values of type xdt: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 $arg
must be numeric or derived from a single base
type. In addition, the type must support addition. Duration values must
either all be xdt:yearMonthDuration
values or must all be
xdt:dayTimeDuration
values. For numeric values, the numeric
promotion rules defined in are used to promote
all values to a single common type. The sum of a sequence of integers will
therefore be an integer, while the sum of a numeric sequence that includes
at least one xs:double will be an xs:double.
If the above conditions are not met, a type error is raised .
Otherwise, the result of the function, using the second signature, is the
result of the expression:
if (fn:count($c) eq 0) then
$zero
else if (fn:count($c) eq 1) then
$c[1]
else
$c[1] + fn:sum(subsequence($c, 2))
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 .
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.
Examples
Assume:
$d1 = xdt:yearMonthDuration("P20Y")
$d2 = xdt:yearMonthDuration("P10M")
$seq1 = ($d1, $d2)</code>
$seq3 = (3, 4, 5)</code>

fn:sum(($d1, $d2))
returns an
xdt:yearMonthDuration
with a value of
250
months.

fn:sum($seq1[. < xdt:yearMonthDuration('P3M')],
xdt:yearMonthDuration('P0M'))
returns an
xdt:yearMonthDuration
with a value of
0
months.

fn:sum($seq3)
returns 12
.

fn:sum(())
returns 0
.

fn:sum((),())
returns ()
.

fn:sum((1 to 100)[.<0], 0)
returns 0
.

fn:sum(($d1, 9E1))
raises an error .
Functions and Operators that Generate Sequences
Function
Meaning
op:to
Returns the sequence containing every xs:integer
between the values of the operands.
fn:id
Returns the sequence of element nodes having an ID value matching
the one or more of the supplied IDREF values.
fn:idref
Returns the sequence of element or attribute nodes with an IDREF
value matching one or more of the supplied ID values.
fn:doc
Returns a document node retrieved using the specified URI.
fn:docavailable
Returns true
if a document node can be retrieved using
the specified URI.
fn:collection
Returns a sequence of nodes retrieved using the specified URI or the
nodes in the default collection.
op:to
Summary: Returns the sequence containing every xs:integer
whose
value is between the value of $firstval
(inclusive) and the
value of $lastval
(inclusive), in monotonic order. If the value
of the first operand is greater than the value of the second, the empty
sequence is returned. If the values of the two operands are equal, a
sequence containing a single xs:integer
equal to the value is returned.
This function backs up the "to" operator.
Examples

1 to 3
returns (1, 2, 3)

3 to 1
returns ()

5 to 5
returns 5
fn:id
Summary: 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 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 node if the second argument is omitted. An error is
raised if
$node
, or the context item if the second argument is
omitted, is a node in a tree whose root is not a document node or if
the second argument is omitted and there is no context item
, or if the
context item is not a 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 .) of the element node
is true, and the typed value of the element node is
equal to 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 .) is true and whose typed value is
equal to 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
spaceseparated 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:
for $s in $arg return fn:tokenize(fn:normalizespace($s), ' ')
[. castable as xs:IDREF]

If several elements have the same ID
value, then
E
is the one that is first in document order.
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 schemadefined type
is 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 an 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.
fn:idref
Summary: 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 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 node if the second argument is omitted. An
error is raised
if $node
, or the context item if the second argument is
omitted, is a node in a tree whose root is not a document node or if
the second argument is omitted and there is no context item
, or if the
context item is not a 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 .)of
$N
is true

The sequence fn:tokenize(fn:normalizespace($N),
' ') contains a string that is equal to
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 $arg[. castable as xs:NCName]
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.
fn:doc
Summary: Retrieves a document using an xs:anyURI
, which may
include a fragment identifier, supplied as an xs:string
. If
$uri
is not a valid xs:anyURI
, an error is raised
. If it is a relative URI Reference,
it is resolved relative to the value of the base URI property from the
static context. The resulting absolute URI Reference is promoted to
an xs:string
. If the Available documents discussed
in provides a mapping from this
string to a document node, the function returns that document node. If the
Available documents maps the string to an empty sequence,
then the function returns an empty sequence. If the Available
documents provides no mapping for the string, an error is raised
.
If $uri
is the empty sequence, the result is an empty sequence.
This function is . Two calls on this function return
the same document node if the same URI Reference (after resolution to an
absolute URI Reference) is supplied to both calls. Thus, the following
expression (if it does not raise an error) will always be true:
doc("foo.xml") is doc("foo.xml")
For detailed type semantics, see .
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, an error is raised . The data
resulting from the retrieval action is then parsed as an XML document and a
tree is constructed in accordance with the . If the
toplevel media type is known and is "text", the content is parsed in the
same way as if the media type were text/xml; otherwise, it is parsed in the
same way as if the media type were application/xml. If the contents cannot
be parsed successfully, an error is raised. Otherwise, the result of the
function is the document node at the root of the resulting tree. This tree
is then optionally validated against a schema.
Various aspects of this processing are . Implementations may provide external
configuration options that allow any aspect of the processing to be
controlled by the user. In particular:

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 whether DTD validation
and/or schema validation is applied to the source document.

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.
fn:docavailable
Summary: If fn:doc($uri)
returns a document node, this function
returns true
. If $uri
is not a valid
xs:anyURI
, an error is raised . Otherwise, this function returns false
.
If this function returns true
, then
calling fn:doc($uri)
within the same must return a document node.
fn:collection
Summary: 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 Available collections described in . If Available
collections provides a mapping from this string to a sequence of
nodes, the function returns that sequence. If Available
collections maps the string to an empty sequence, then the function
returns an empty sequence. If Available collections provides no
mapping for the string, an error is raised . If $arg
is not specified, the function returns
the sequence of the nodes in the default collection in the dynamic context.
See . If the
value of the default collection is undefined an error is raised .
If the $arg
is a relative xs:anyURI
, it is
resolved against the value of the baseURI property from the static context.
If $arg
is not a valid xs:anyURI
, an error is raised .
If $arg
is the empty sequence, the function behaves as if it had
been called without an argument. See above.
This function is . For detailed type semantics, see
.
This function provides a facility for users to work with a collection of
documents which may be contained in a directory or rows of a Relational
table or 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.
Context Functions
The following functions are defined to obtain information from the dynamic context.
Function
Meaning
fn:position
Returns the position of the context item within the sequence of items
currently being processed.
fn:last
Returns the number of items in the sequence of items currently being processed.
fn:currentdateTime
Returns the current xs:dateTime
.
fn:currentdate
Returns the current xs:date
.
fn:currenttime
Returns the current xs: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
Returns the value of the baseuri property from the static context.
fn:position
Summary: Returns the context position from the dynamic context.
(See .) If the
context item is undefined, an error is raised .
fn:last
Summary: Returns the context size from the dynamic context.
(See .) If the context item is undefined,
an error is raised .
fn:currentdateTime
Summary: Returns the current dateTime (with timezone) from the dynamic context.
(See .) This
is an 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 . The precise instant during the query or transformation
represented by the value of fn:currentdateTime()
is .
Examples

fn:currentdateTime()
returns an
xs:dateTime
corresponding to the current date and time.
For example, an invocation of fn:currentdateTime()
might return 20040512T18:17:15.125Z
corresponding to
the current time on May 12, 2004 in timezone Z
.
fn:currentdate
Summary: 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 . The precise instant
during the query or transformation represented by the value of
fn:currentdate()
is .
Examples

fn:currentdate()
returns an xs:date
corresponding to the current date and time. For example, an
invocation of fn:currentdate()
might return
20040512+01:00
.
fn:currenttime
Summary: 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 . The precise instant
during the query or transformation represented by the value of
fn:currenttime()
is .
Examples

fn:currenttime()
returns an xs:time
corresponding to the current date and time. For example, an
invocation of fn:currenttime()
might return
23:17:00.00005:00
.
fn:implicittimezone
Summary: Returns the value of the implicit timezone property from the dynamic
context. Components of the dynamic context are discussed in .
fn:defaultcollation
Summary: 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 undefined. If it is not
explicitly defined, a system defined default can be invoked. If this is not
provided, the Unicode code point collation
(http://www.w3.org/2005/xpathfunctions/collation/codepoint
)
is used.
fn:staticbaseuri
Summary: Returns the value of the baseuri property from the static context. If
the baseuri property is undefined, the empty sequence is returned. Components
of the static context are discussed in .
Casting
Constructor functions and cast expressions accept an expression and return a value
of a given type. They both convert a source value, SV , of a source type,
ST , to a target value, TV , of the given target type,
TT , with identical semantics and different syntax. The name of a
constructor function is the same as the name of the builtin
type (see ) or userderived type
(see ) that is the
target for the conversion, and the semantics are exactly the same as for a cast
expression; for example,
xs:date("20030101")
means exactly the same as
"20030101"
cast as
xs:date?
.
The cast expression takes a type name to indicate the target type of the conversion.
See . If the type name allows the empty sequence
and the expression to be cast is the empty sequence, the empty sequence is returned.
If the type name does not allow the empty sequence and the expression to be cast is
the empty sequence, a type error is raised .
Where the argument to a cast is a literal, the result of the function may be
evaluated statically; if an error is encountered during such evaluation, it may be
reported as a static error.
Casting from primitive types to primitive types
This section defines casting between the 19 primitive types defined in as well as xdt:untypedAtomic
,
xs:integer
and the two derived types of
xs:duration
(xdt:yearMonthDuration
and xdt:dayTimeDuration
). These four types are not primitive types
but they are treated as primitive types in this section. The type conversions
that are supported are indicated in the table below. In this table, there is a
row for each primitive type with that type as the source of the conversion and
there is a column for each primitive type 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 fails for others.
defines xs:NOTATION
as an abstract type.
Thus, casting to xs:NOTATION
from any other type including xs:NOTATION
is not permitted. However, casting from one subtype of 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 xdt:untypedAtomic
.
There are no atomic values with the type annotation xs:anySimpleType
at runtime.
Similarly, casting is not supported to or from xdt:anyAtomicType
. There are no atomic values with the type annotation xdt
:anyAtomicType
at runtime, although this can be a statically inferred type.
An attempt to cast to any of the above three type raises a static error
If casting is attempted from an ST to a TT for which
casting is not supported, as defined in the table below, an error is raised .
In the following table, the columns and rows are identified by short codes that
identify simple types as follows:
uA = xdt:untypedAtomic
aURI = xs:anyURI
b64 = xs:base64Binary
bool = xs:boolean
dat = xs:date
gDay = xs:gDay
dbl = xs:double
dec = xs:decimal
dT = xs:dateTime
dTD = xdt:dayTimeDuration
dur = xs:duration
flt = xs:float
hxB = xs:hexBinary
gMD = xs:gMonthDay
gMon = xs:gMonth
int = xs:integer
NOT = xs:NOTATION
QN = xs:QName
str = xs:string
tim = xs:time
gYM = xs:gYearMonth
yMD = xdt:yearMonthDuration
gYr = xs:gYear
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
N
N
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
N
NOT
Y
Y
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
M
The following subsections define the semantics of casting from a primitive type
to a primitive type. Semantics of casting to and from a derived type are defined
in sections , ,
and .
Casting from xs:string and xdt:untypedAtomic
When the supplied value is an instance of xs:string
or an
instance of xdt:untypedAtomic
, it is treated as being a string
value and mapped to a typed value of the target type as defined in . Whitespace normalization is applied as indicated by the
whiteSpace facet for the datatype. The resulting whitespacenormalized string must be a valid lexical form for the datatype. The semantics of casting are identical to
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")
.
When casting from xs:string
or xdt:untypedAtomic
to a derived type where the derived type is restricted by a pattern facet, the
lexical form is first checked against the pattern before further casting is attempted (See ). If the lexical form does not conform to the pattern, error is raised.
Consider a userdefined Schema whose target namespace is bound to the prefix mySchema
which defines a restriction of xs:boolean
called trueBool
which allows only the lexical forms 1
and 0
. "true" cast as mySchema:trueBool
would fail with . If the Schema also defines a datatype called height
as a restriction of xs:integer
with a maximum value of 84
then "100" cast as mySchema:height
would also fail with .
Casting is permitted from xs:string
and
xdt:untypedAtomic
to any primitive atomic type or any atomic
type derived by restriction, except xs:QName
or xs:NOTATION
. Casting to xs:NOTATION
is not permitted because it is an abstract type.
Casting is permitted from xs:string
literals to xs:QName
and types derived from xs:NOTATION
. A static error is raised if the argument to a cast for xs:QName
or a type derived from xs:QName
or xs:NOTATION
is not an xs:string
literal.
In casting to numerics, 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 .
In casting to a date or time value, if the value is too large or too small to be represented by the implementation, error is raised.
In casting to a duration value, if the value is too large or too small to be represented by the implementation, error is raised.
For xs:anyURI
, the extent to which an implementation validates the
lexical form of xs:anyURI
is .
If the cast fails for any other reason, error is raised.
Casting to xs:string and xdt:untypedAtomic
Casting is permitted from any primitive type to the primitive types
xs:string
and xdt:untypedAtomic
.
When a value of any simple type is cast as xs:string
, the
derivation of the xs:string
value TV depends on
the ST and on the SV , as follows.

If ST is xs:string
or a type derived from
xs:string
, TV is SV .

If ST is xs:anyURI
, the type conversion is
performed without escaping any characters.

If ST is xs:QName
,
TV is fn:concat(fn:prefixfromQName(
SV
), ":",
fn:localnamefromQName(
SV
))
.

If ST is a numeric type, the following rules apply:

If ST is xs:integer
,
TV is the canonical lexical representation of
SV as defined in . There
is no decimal point.

If ST is xs:decimal
, then:

If SV is in the value space of
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
SV is returned, as defined in .

If ST is xs:float
or
xs:double
, then:

If SV has an absolute value that is
greater than or equal to 0.000001 (one millionth)
and less than 1000000 (one million), then the value
is converted to an 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 SV has the value positive or negative zero, TV is "0" or "0"
respectively.

Otherwise, the canonical lexical representation of
SV value is returned. This is defined
as follows: NaN has the canonical form "NaN".
Infinity and negative infinity have the canonical
forms "INF" and "INF" respectively. Besides these
special values, the general form of the canonical
form for xs:float
and
xs:double
is a mantissa, which is a
xs:decimal
, followed by the letter "E",
followed by an exponent which is
an xs:integer
. Leading zeroes and the
preceding optional "+" sign are prohibited in the
exponent. If the exponent is zero it must be
indicated by "E0". For the mantissa, the preceding
optional "+" sign is prohibited and the decimal
point is required. Leading and trailing zeroes are
prohibited subject to the following: number
representations must be normalized such that there
is a single digit which is nonzero to the left of
the decimal point and at least a single digit to the
right of the decimal point unless the value being
represented is zero. Beyond the one required digit
after the decimal point in the mantissa, there must
be as many, but only as many, additional digits as
are needed to uniquely distinguish the value from
all other values for the datatype after rounding the
final digit.
The above wording has been accepted by the XML
Schema Working Group for the canonical form of
the xs:float
and xs:double
datatypes. When this
wording appears in a publicly available
document the paragraph above will be replaced by
an appropriate reference.

If ST is xs:dateTime
, xs:date
or xs:time
, TV is the local value.
The components of TV are individually cast to xs:string
using the functions described in and the results are concatenated together. The 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 ST is xdt:yearMonthDuration
or xdt:dayTimeDuration
, TV is the
canonical representation of SV as defined in or , respectively.

If ST is xs:duration
then let SYM be SV
cast as xdt:yearMonthDuration
, and let SDT be SV
cast as xdt:dayTimeDuration
; Now, let the next intermediate value, TYM ,
be SYM
cast as
TT
, and let TDT be SDT
cast as
TT
. If TYM is "P0M", then TV is
TDT . Otherwise, TYM and TDT are merged according to the following rules:
If TDT is "PT0S", then TV is TYM .
Otherwise, TV is the concatenation of all the characters in TYM and all the
characters except the first "P" and the optional negative sign in TDT .

In all other cases, TV is the
canonical representation of SV . For datatypes that do
not have a canonical lexical representation defined an canonical representation may be used.
To cast as xdt:untypedAtomic
the value is cast as
xs:string
, as described above, and the type annotation changed
to xdt: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
.
Casting to numeric types
Casting to xs:float
When a value of any simple type is cast as xs:float
, the xs:float
TV is derived from the ST and the
SV as follows:

If ST is xs:float
, then TV
is SV and the conversion is complete.

If ST is xs:double
, then
TV is obtained as follows:

if SV is the xs:double
value
INF
, INF
, NaN
,
positive zero, or negative zero, then TV is
the xs:float
value INF
,
INF
, NaN
, positive zero, or
negative zero respectively.

otherwise, SV can be expressed in the form
m × 2^e
where the mantissa
m
and exponent e
are signed
xs:integer
s whose value range is defined in
, and the following rules apply:

if m
(the mantissa of
SV ) is outside the permitted range
for the mantissa of an xs:float
value (2^24+1 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 TV is
the 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 TV is
the xs:float
value positive or
negative zero depending on the sign of M

otherwise, TV is the
xs:float
value M × 2^E
.

If ST is xs:decimal
, or
xs:integer
, then TV is xs:float(
SV
cast as xs:string)
and the conversion is complete.

If ST is xs:boolean
, SV is
converted to 1.0E0
if SV is
true
and to 0.0E0
if SV
is false
and the conversion is complete.

If ST is xdt:untypedAtomic
or xs:string
, see
.
Implementations return negative zero for
"0.0E0" cast as xs:float
. does not distinguish between the values positive zero and negative zero.
Casting to xs:double
When a value of any simple type is cast as xs:double
, the
xs:double
value TV is derived from the
ST and the SV as follows:

If ST is xs:double
, then
TV is SV and the conversion is complete.

If ST is xs:float
or a type derived
from xs:float
, then TV is obtained as follows:

if SV is the xs:float
value
INF
, INF
, NaN
,
positive zero, or negative zero, then TV is
the xs:double
value INF
,
INF
, NaN
, positive zero, or
negative zero respectively.

otherwise, SV can be expressed in the form
m × 2^e
where the
mantissa m
and exponent e
are
signed xs:integer
values whose value range
is defined in , and
TV is the xs:double
value
m × 2^e
.

If ST is xs:decimal
or
xs:integer
, then TV is xs:double(
SV
cast as xs:string)
and the conversion is complete.

If ST is xs:boolean
, SV is
converted to 1.0E0
if SV is
true
and to 0.0E0
if SV
is false
and the conversion is complete.

If ST is xdt:untypedAtomic
or xs:string
, see
.
Implementations return negative zero for
"0.0E0" cast as xs:double
. does not distinguish between the values positive zero and negative zero.
Casting to xs:decimal
When a value of any simple type is cast as xs:decimal
, the
xs:decimal
value TV is derived from
ST and SV as follows:

If ST is xs:decimal
,
xs:integer
or a type derived from them, then
TV is SV , converted to an
xs:decimal
value if need be, and the conversion is complete.

If ST is xs:float
or
xs:double
, then TV is the
xs:decimal
value, within the set of
xs:decimal
values that the implementation is
capable of representing, that is numerically closest to
SV . If two values are equally close, then the one
that is closest to zero is chosen. If SV is too
large to be accommodated as an xs:decimal
, (see
for limits on
numeric values) an error is raised . If SV is one of the special
xs:float
or xs:double
values
NaN
, INF
, or INF
, an
error is raised .

If ST is xs:boolean
, SV is
converted to 1.0
if SV is
1
or true
and to 0.0
if
SV is 0
or false
and the
conversion is complete.

If ST is xdt:untypedAtomic
or xs:string
, see
.
Casting to xs:integer
When a value of any simple type is cast as xs:integer
, the
xs:integer
value TV is derived from
ST and SV as follows:

If ST is xs:integer
, or a type derived
from xs:integer
, then TV is
SV , converted to an xs:integer
value
if need be, and the conversion is complete.

If ST is
xs:decimal
, xs:float
or
xs:double
, then TV is SV
with the fractional part discarded and the value converted to
xs:integer
. Thus, casting 3.1456
returns 3
and 17.89
returns
17
. Casting 3.124E1
returns 31
. If SV is too large to be
accommodated as an integer, (see for
limits on numeric values) an error is
raised . If SV is
one of the special xs:float
or
xs:double
values NaN
,
INF
, or INF
, an error is raised
.

If ST is xs:boolean
, SV is
converted to 1
if SV is 1
or true
and to 0
if SV is
0
or false
and the conversion is complete.

If ST is xdt:untypedAtomic
or xs:string
, see
.
Casting to duration types
When a value of type xdt:untypedAtomic
, xs:string
,
a type derived from xs:string
,
xdt:yearMonthDuration
or xdt:dayTimeDuration
is
cast as xs:duration
, xdt:yearMonthDuration
or
xdt:dayTimeDuration
, TV is derived from
ST and SV as follows:

If ST is the same as TT , then
TV is SV .

If ST is xs:duration
, or a type derived
from xs:duration
, but not
xdt:dayTimeDuration
or a type derived from
xdt:dayTimeDuration
, and TT is
xdt:yearMonthDuration
, then TV is derived
from SV by removing the day, hour, minute and second
components from SV .

If ST is xs:duration
, or a type derived
from duration
, but not
xdt:yearMonthDuration
or a type derived from
xdt:yearMonthDuration
, and TT is
xdt:dayTimeDuration
, then TV is derived
from SV by removing the year and month components from SV .

If ST is xdt:yearMonthDuration
or xdt:dayTimeDuration
, and TT is
xs:duration
, then TV is derived from
SV as discussed in .

If ST is xdt:yearMonthDuration
and TT is
xdt:dayTimeDuration
, the cast is permitted and returns a xdt:dayTimeDuration
with value 0.0 seconds.

If ST is xdt:dayTimeDuration
and TT is
xdt:yearMonthDuration
, the cast is permitted and returns a xdt:yearMonthDuration
with value 0 months.

If ST is xdt:untypedAtomic
or xs:string
, see
.
Note that casting from xs:duration
to
xdt:yearMonthDuration
or xdt:dayTimeDuration
loses
information. To avoid this, users can cast the xs:duration
value to both an xdt:yearMonthDuration
and an
xdt:dayTimeDuration
and work with both values.
Casting to date and time types
In several situations, casting to date and time types requires the extraction
of a component from SV or from the result of
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.
declare function eg:convertYearToString($year as xs:integer) as xs:string
{
let $plusMinus := if ($year >= 0) then "" else ""
let $yearString := fn:abs($year) cast as xs:string
let $length := fn:length($yearString)
return
if ($length = 1) then fn:concat($plusMinus, "000", $yearString)
else
if ($length = 2) then fn:concat($plusMinus, "00", $yearString)
else
if ($length = 3) then fn:concat($plusMinus, "0", $yearString)
else fn:concat($plusMinus, $yearString)
}
declare function eg:convertTo2CharString($value as xs:integer) as xs:string
{
let $string := $value cast as xs:string
return
if (fn:length($string) = 1) then fn:concat("0", $string)
else $string
}
declare function eg:convertSecondsToString($seconds as xs:decimal) as xs:string
{
let $string := $seconds cast as xs:string
let $intLength := fn:length(($seconds cast as xs:integer) cast as xs:string)
return
if ($intLength = 1) then fn:concat("0", $string)
else $string
}
declare function eg:convertTZtoString($tz as xdt:dayTimeDuration?) as xs:string
{
if (empty($tz)) then ""
else
let $tzh := fn:hoursfromdayTimeDuration($tz)
let $tzm := fn:minutesfromdayTimeDuration($tz)
let $plusMinus := if ($tzh >= 0) then "+" else ""
let $tzhString := eg:convertTo2CharString(fn:abs($tzh))
let $tzmString := eg:convertTo2CharString(fn:abs($tzm))
return fn:concat($plusMinus, $tzhString, ":", $tzmString)
}
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
, xs:time
,
xs:date
, xs:gYearMonth
,
xs:gYear
, xs:gMonthDay
,
xs:gDay
, or xs:gMonth
,
let CYR be eg:convertYearToString(
fn:yearfromdateTime( fn:currentdateTime() ))
,
let CMO be eg:convertTo2CharString(
fn:monthfromdateTime( fn:currentdateTime() ))
,
let CDA be eg:convertTo2CharString(
fn:dayfromdateTime( fn:currentdateTime() ))
.

When a value of any primitive type is cast as
xs:dateTime
, the xs:dateTime
value
TV is derived from ST and SV
as follows:

If ST is xs:dateTime
, then
TV is SV .

If ST is xs:date
, then let
SYR be eg:convertYearToString( fn:yearfromdate(
SV
))
, let SMO be
eg:convertTo2CharString( fn:monthfromdate(
SV
))
, let SDA be
eg:convertTo2CharString( fn:dayfromdate(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdate(
SV
))
; TV is xs:dateTime( fn:concat(
SYR
, '',
SMO
, '',
SDA
, 'T00:00:00 '
, STZ
) )
.

If ST is xdt:untypedAtomic
or
xs:string
, see
.

When a value of any primitive type is cast as xs:time
,
the xs:time
value TV is derived from
ST and SV as follows:

If ST is xs:time
, then
TV is SV .

If ST is xs:dateTime
, then
TV is xs:time( fn:concat(
eg:convertTo2CharString( fn:hoursfromdateTime(
SV
)), ':', eg:convertTo2CharString( fn:minutesfromdateTime(
SV
)), ':', eg:convertSecondsToString( fn:secondsfromdateTime(
SV
)), eg:convertTZtoString( fn:timezonefromdateTime(
SV
)) ))
.

If ST is xdt:untypedAtomic
or xs:string
, see
.

When a value of any primitive type is cast as xs:date
,
the xs:date
value TV is derived from
ST and SV as follows:

If ST is xs:date
, then
TV is SV .

If ST is xs:dateTime
, then let
SYR be eg:convertYearToString( fn:yearfromdateTime(
SV
))
, let SMO be
eg:convertTo2CharString( fn:monthfromdateTime(
SV
))
, let SDA be
eg:convertTo2CharString( fn:dayfromdateTime(
SV
))
and let STZ be eg:convertTZtoString(fn:timezonefromdateTime(
SV
))
; TV is xs:date( fn:concat(
SYR
, '',
SMO
, '',
SDA , STZ
) )
.

If ST is xdt:untypedAtomic
or xs:string
, see
.

When a value of any primitive type is cast as
xs:gYearMonth
, the xs:gYearMonth
value
TV is derived from ST and SV
as follows:

If ST is xs:gYearMonth
, then
TV is SV .

If ST is xs:dateTime
, then let
SYR be eg:convertYearToString( fn:yearfromdateTime(
SV
))
, let SMO be
eg:convertTo2CharString( fn:monthfromdateTime(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdateTime(
SV
))
; TV is xs:gYearMonth( fn:concat(
SYR
, '',
SMO , STZ
) )
.

If ST is xs:date
, then let
SYR be eg:convertYearToString( fn:yearfromdate(
SV
))
, let SMO be
eg:convertTo2CharString( fn:monthfromdate(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdate(
SV
))
; TV is xs:gYearMonth( fn:concat(
SYR
, '',
SMO , STZ
) )
.

If ST is xdt:untypedAtomic
or xs:string
, see
.

When a value of any primitive type is cast as xs:gYear
,
the xs:gYear
value TV is derived from
ST and SV as follows:

If ST is xs:gYear
, then
TV is SV .

If ST is xs:dateTime
, let
SYR be eg:convertYearToString( fn:yearfromdateTime(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdateTime(
SV
))
; TV is xs:gYear(fn:concat(
SYR , STZ
))
.

If ST is xs:date
, let
SYR be eg:convertYearToString( fn:yearfromdate(
SV
))
; and let STZ be
eg:convertTZtoString( fn:timezonefromdate(
SV
))
; TV is xs:gYear(fn:concat(
SYR , STZ
))
.

If ST is xdt:untypedAtomic
or xs:string
, see
.

When a value of any primitive type is cast as
xs:gMonthDay
, the xs:gMonthDay
value
TV is derived from ST and SV
as follows:

If ST is xs:gMonthDay
, then
TV is SV .

If ST is xs:dateTime
, then let
SMO be eg:convertTo2CharString( fn:monthfromdateTime(
SV
))
, let SDA be
eg:convertTo2CharString( fn:dayfromdateTime(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdateTime(
SV
))
; TV is xs:gYearMonth( fn:concat(
'',
SMO
'',
SDA , STZ
) )
.

If ST is xs:date
, then let
SMO be eg:convertTo2CharString( fn:monthfromdate(
SV
))
, let SDA be
eg:convertTo2CharString( fn:dayfromdate(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdate(
SV
))
; TV is xs:gYearMonth( fn:concat(
'',
SMO
, '',
SDA , STZ
) )
.

If ST is xdt:untypedAtomic
or xs:string
, see
.

When a value of any primitive type is cast as xs:gDay
,
the xs:gDay
value TV is derived from
ST and SV as follows:

If ST is xs:gDay
, then
TV is SV .

If ST is xs:dateTime
, then let
SDA be eg:convertTo2CharString( fn:dayfromdateTime(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdateTime(
SV
))
; TV is xs:gDay(
fn:concat( ''
, SDA , STZ
))
.

If ST is xs:date
, then let
SDA be eg:convertTo2CharString( fn:dayfromdate(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdate(
SV
))
; TV is xs:gDay(
fn:concat( ''
, SDA , STZ
))
.

If ST is xdt:untypedAtomic
or xs:string
, see
.

When a value of any primitive type is cast as xs:gMonth
,
the xs:gMonth
value TV is derived from
ST and SV as follows:

If ST is xs:gMonth
, then
TV is SV .

If ST is xs:dateTime
, then let
SMO be eg:convertTo2CharString( fn:monthfromdateTime(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdateTime(
SV
))
; TV is xs:gMonth(
fn:concat( ''
, SMO , STZ
))
.

If ST is xs:date
, then let
SMO be eg:convertTo2CharString( fn:monthfromdate(
SV
))
and let STZ be
eg:convertTZtoString( fn:timezonefromdate(
SV
))
; TV is xs:gMonth(
fn:concat( ''
, SMO , STZ
))
.

If ST is xdt:untypedAtomic
or xs:string
, see
.
Casting to xs:boolean
When a value of any primitive type is cast as xs:boolean
, the
xs:boolean
value TV is derived from
ST and SV as follows:

If ST is xs:boolean
, then TV
is SV .

If ST is xs:float
, xs:double
,
xs:decimal
or xs:integer
and
SV is 0
, +0
, 0
,
0.0
, 0.0E0
or NaN
, then
TV is false
.

If ST is xs:float
, xs:double
,
xs:decimal
or xs:integer
and
SV is not one of the above values, then TV
is true
.

If ST is xdt:untypedAtomic
or xs:string
, see
.
Casting to xs:base64Binary and xs:hexBinary
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
xdt:untypedAtomic
, xs:string
and subtypes of
xs:string
using semantics.
Casting to xs:anyURI
Casting to xs:anyURI
is supported only from the same type,
xdt:untypedAtomic
or xs:string
.
When a value of any primitive type is cast as xs:anyURI
, the
xs:anyURI
value TV is derived from the
ST and SV as follows:

If ST is xdt:untypedAtomic
or xs:string
see
.
Casting to derived types
Casting a value to a derived type can be separated into four cases. Note that
xdt:untypedAtomic
, xs:integer
and the two derived
types of xs:duration
:xdt:yearMonthDuration
and xdt:dayTimeDuration
are treated as primitive types.

When SV is an instance of a type that is derived by
restriction from TT . This is described in section .

When SV is an instance of a type derived by restriction from
the same primitive type as TT . This is described in
.

When the derived type is derived, directly or indirectly, from a
different primitive type than the primitive type of ST .
This is described in .

When SV is an instance of the TT , the cast
always succeeds (Identity cast).
Casting from derived types to parent types
It is always possible to cast a value of any atomic type to an atomic type from
which it is derived, directly or indirectly, by restriction. For example, it is
possible to cast an xs:unsignedShort
to an
xs:unsignedInt
, an xs:integer
, or an
xs:decimal
. Since the value space of the original type is a subset
of the value space of the target type, such a cast is always successful. The
result will have the same value as the original, but will have a new type annotation.
Casting within a branch of the type hierarchy
It is possible to cast an SV to a TT if the type of the
SV and the TT type are both derived by restriction
(directly or indirectly) from the same primitive type, provided that the
supplied value conforms to the constraints implied by the facets of the target
type. This includes the case where the target type is derived from the type of the supplied value,
as well as the case where the type of the supplied value is derived from the target type. For example, an instance of xs:byte
can be cast as
xs:unsignedShort
, provided the value is not negative.
If the value does not conform to the facets defined for the target type, then an
error is raised . See .
In the case of the pattern facet (which applies to the lexical space rather than
the value space), the pattern is tested against the canonical lexical
representation of the value, as defined for the source type (or the result
of casting the value to an xs:string
, in the case of types that have no canonical
lexical representation defined for them).
Note that this will cause casts to fail if the pattern excludes the canonical
lexical representation of the source type. For example, if the type
my:distance
is defined as a restriction of xs:decimal
with a pattern that requires two digits after the decimal point, casting of an
xs:integer
to my:distance
will always fail, because
the canonical representation of an xs:integer
does not conform to
this pattern.
In some cases, casting from a parent type to a derived type requires special
rules. See for rules regarding casting to
xdt:yearMonthDuration
and xdt:dayTimeDuration
. See , below, for casting to xs:ENTITY
and types derived from it.
Casting to xs:ENTITY
says that 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,
and do not check that constructed values of type 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.
Casting across the type hierarchy
When the ST and the TT are derived, directly or
indirectly, from different primitive types, this is called casting across the
type hierarchy. Casting across the type hierarchy is logically equivalent to
three separate steps performed in order. Errors can occur in either of the
latter two steps.

Cast the SV , up the hierarchy, to the primitive type of the
source, as described in .
If SV is an instance of xs:string
or xdt:untypedAtomic
, check its value against the pattern facet of TT , and raise an error if the check fails.

Cast the value to the primitive type of TT , as described in
.

Cast the value down to the TT , as described in
References
Normative References
IEEE. IEEE Standard for
Binary FloatingPoint Arithmetic.
Unicode Technical
Standard #35, Locale Data Markup Language. Available at:
http://www.unicode.org/unicode/reports/tr35/
IETF. RFC 2396: Uniform
Resource Identifiers (URI): Generic Syntax. Available at:
http://www.ietf.org/rfc/rfc2396.txt
IETF. RFC 3986: Uniform
Resource Identifiers (URI): Generic Syntax. Available at:
http://www.ietf.org/rfc/rfc3986.txt
IETF. RFC 3987:
Internationalized Resource Identifiers (IRIs). Available at:
http://www.ietf.org/rfc/rfc3987.txt
Character Model for the World Wide Web 1.0:
Fundamentals. Available at:
http://www.w3.org/TR/2005/RECcharmod20050215/
Character Model for the World Wide Web
1.0: Normalization, Last Call Working Draft. Available at:
http://www.w3.org/TR/2004/WDcharmodnorm20040225/
ISO (International Organization
for Standardization). ISO/IEC 109671:1994, Information
technology—Language Independent Arithmetic—Part 1:
Integer and floating point arithmetic [Geneva]: International
Organization for Standardization, 1994. Available from: http://www.iso.ch/
The Unicode Consortium, Reading, MA, AddisonWesley, 2003. The Unicode Standard
as updated from time to time by the publication of new versions. See
http://www.unicode.org/unicode/standard/versions
for the latest version and additional information on versions of the standard and of the Unicode Character Database. The version of Unicode to be used is , but implementations are recommended to use the latest Unicode version; currently, Version 4.0.00, AddisonWesley, 2003 ISBN 0321185781
Unicode Technical Standard #10, Unicode Collation
Algorithm. Available at:
http://www.unicode.org/unicode/reports/tr10/
Unicode
Technical Standard #18, Unicode Regular Expressions. Available at:
http://www.unicode.org/unicode/reports/tr18/
World Wide Web
Consortium. Extensible Markup Language (XML) 1.0 Third Edition.
Available at: http://www.w3.org/TR/RECxml
World Wide Web
Consortium. Extensible Markup Language (XML) 1.1.
Available at: http://www.w3.org/TR/2004/RECxml1120040204/
World Wide Web Consortium. XML Path Language
(XPath) Version 2.0. Available at: http://www.w3.org/TR/xpath20/
World Wide Web Consortium. XSL Transformations
Version 2.0. Available at: http://www.w3.org/TR/xslt20/
World Wide Web
Consortium. XQuery 1.0 and XPath 2.0 Data Model (XDM). Available at: http://www.w3.org/TR/querydatamodel/
World Wide Web Consortium. XQuery 1.0 and XPath 2.0 Formal Semantics.
Available at: http://www.w3.org/TR/querysemantics/
World Wide Web
Consortium. XQuery 1.0: An XML Query Language. Available at: http://www.w3.org/TR/xquery/
XML
Schema Part 1: Structures Second Edition, Oct 28 2004. Available at: http://www.w3.org/TR/xmlschema1/
XML Schema
Part 2: Datatypes Second Edition, Oct. 28 2004. Available at: http://www.w3.org/TR/xmlschema2/
Namespaces in XML. Available at:
http://www.w3.org/TR/1999/RECxmlnames19990114/
Nonnormative References
HTML 4.01 Recommendation, 24 December
1999. Available at:
http://www.w3.org/TR/REChtml40/
ISO (International Organization for
Standardization). Representations of dates and times,
20000803. Available from:
http://www.iso.ch/"
World Wide Web Consortium Working Group Note. Working With Timezones, October 13, 2005. Available at:
http://www.w3.org/TR/2005/NOTEtimezone20051013/
World Wide Web Consortium. XML Path Language (XPath) Version 1.0 Available at:
http://www.w3.org/TR/xpath
Change Log for this Version of the Document
Some of the more significant changes that appear in this version of the document with respect to the last call version http://www.w3.org/TR/2005/WDxpathfunctions20050404/
are listed below. A complete list of comments against the last call version of the document can be found in the Bugzilla database for product "XPath/XQuery/XSLT" and component "Functions and Operators". A list of bugs that have been resolved or closed can be found at:
resolved comments .

A reference has been added from the section entitled to
, a W3C Note prepared by the I18N WG that discusses problems, pitfalls and solutions for writing applications that work with date and time values with and without timezones.

The fn:escapeuri
function has been removed and replaced with 2 functions called fn:encodeforuri
and
fn:iritouri
corresponding to the behaviour of fn:escapeuri
with the parameter
escapereserved
set to TRUE
and FALSE
respectively.

Values of type xs:duration
can now be compared for equality using the new function op:durationequal
.

Values of type xs:duration
can now be cast to xs:string
.

The functions fn:subtractdateTimesyieldingdayTimeDuration
and fn:subtractdatesyieldingdayTimeDuration
have been renamed fn:subtractdateTimes
and fn:subtractdates
, respectively.

The rules for functions returning positive zero or negative zero have been clarified. Since does not distinguish between these two values, functions that return positive zero or negative zero are free to return either value.

A new function fn:escapehtmluri
has been added to mimic the html 4.0 URI escaping behavior on attributes. The serialization specification escapes URIs in this manner and it was felt to be useful to make this functionality available as a function.

Casting from xs:string
and xdt:untypedAtomic
to derived types has been clarified. If the derived type is restricted by a pattern, the lexical form is first checked against the pattern. See .
Section has been clarified to say that although casting is not permitted from xs:NOTATION
to
xs:NOTATION
, since it is an abstract type, casting is permitted from one subtype of xs:NOTATION
to another. The entry in the table at the intersection of xs:NOTATION
and xs:NOTATION
has consequently been changed to "M".

This document now does support leap seconds. Wording has been changed in several places to reflect this decision.
We have been made aware of ongoing work to provide URIbased names for collations and
collation algorithms and to create an IANA registry for such names. See memberonly
communication: http://lists.w3.org/Archives/Member/w3cqueryoperators/2003Aug/0017.html .
References to this work may also appear in future versions of this document.
Error Summary
The error text provided with these errors is nonnormative.
Unidentified error.
This error is raised whenever an attempt is made to divide by zero.
This error is raised whenever numeric operations result in an overflow or underflow.
.
Compatibility with XPath 1.0
This appendix summarizes the relationship between certain functions defined in
and the corresponding functions defined in this document.
The first column of the table provides the signature of functions defined in this
document. The second column provides the signature of the corresponding function in
. The third column discusses the differences in the
semantics of the corresponding functions. The functions appear in the order they
appear in .
The evaluation of the arguments to the functions defined in this document depends on
whether the XPath 1.0 compatibility mode is on or off. See .
If the mode is on, the following conversions are applied, in order, before the
argument value is passed to the function:

If the expected type is a single item or an optional single item, (examples:
xs:string, xs:string?, xdt:untypedAtomic, xdt:untypedAtomic?,
node(), node()?, item(), item()?
), then the given value
V
is effectively replaced by fn:subsequence(V, 1, 1)
.

If the expected type is xs:string
or xs:string?
,
then the given value V
is effectively replaced by fn:string(V)
.

If the expected type is numeric or optional numeric, then the given value
V
is effectively replaced by fn:number(V)
.

Otherwise, the given value is unchanged.
XQuery 1.0 and XPath 2.0
XPath 1.0
Notes
last() => number
Precision of numeric results may be different.
position() => number
Precision of numeric results may be different.
count(nodeset) => number
Precision of numeric results may be different.
id(object) => nodeset
XPath 2.0 behavior is different for boolean and numeric arguments. The
recognition of a node as an id value is sensitive to the manner in which
the datamodel is constructed. In XPath 1.0 the whole string is treated
as a unit. In XPath 2.0 each string is treated as a list.
localname(nodeset?) => string
If compatibility mode is off, an error will occur if
argument has more than one node.
namespaceuri(nodeset?) => string
If compatibility mode is off, an error will occur if
argument has more than one node.
name(nodeset?) => string
If compatibility mode is off, an error will occur if argument has more
than one node. The rules for determining the prefix are more precisely
defined in . Function is not "welldefined" for
parentless attribute nodes.
string(object) => string
If compatibility mode is off, an error will occur if
argument has more than one node. Representations of numeric values are
XPath 1.0 compatible except for the special values positive and negative
infinity, and for values outside the range 1.0e6 to 1.0e+6.
concat(string, string, string*) => string
If compatibility mode is off, an error will occur if
argument has more than one node or if argument is a number or a boolean.
If compatibility mode on, implicit conversion is performed.
startswith(string, string) => boolean
In 1.0, returns false
if the first argument is
an empty nodeset. In 2.0, returns ()
. If compatibility
mode is off, an error will occur if argument has more than one node or
if argument is a number or a boolean. If compatibility mode is on,
implicit conversion is performed.
contains(string, string) => boolean
In 1.0, returns false
if the first argument is
an empty nodeset. In 2.0, returns ()
. If compatibility
mode is off, an error will occur with more than one node and a
nonstring argument results in a type error.
substringbefore(string, string) => string
In 1.0, returns ""
if the first argument is an
empty nodeset. In 2.0, returns ()
. If compatibility mode
is off, numbers and booleans will give errors. Multiple nodes and more
than one value will also give error.
substringafter(string, string) => string
In 1.0, returns ""
if the first argument is an
empty nodeset. In 2.0, returns ()
. If compatibility mode
is off, numbers and booleans will give errors. Multiple nodes and more
than one value will also give error.
substring(string, number, number?) => string
In 1.0, returns ""
if the first argument is an
empty nodeset. In 2.0, returns ()
.
stringlength(string?) => number
If you apply fn:stringlength(@a) == 0
; In 1.0
returns true if @a
does not exist. In 2.0 returns false.
normalizespace(string?) => string
In 1.0, returns ""
if the first argument is an
empty nodeset. In 2.0, returns ()
. If compatibility mode
is off, numbers and booleans will give errors for first arg. Also,
multiple nodes will give error.
translate(string, string, string)=> string
.
boolean(object) => boolean
not(boolean) => boolean
true() => boolean
false() => boolean
lang(string) => boolean
If compatibility mode is off, numbers and booleans will give errors.
Also, multiple nodes will give error. If compatibility mode is on,
implicit conversion is performed.
number(object?) => number
Error if argument has more than one node when not in
compatibility node.
sum(nodeset) => number
2.0 raises an error if sequence contains values that cannot be added
together such as NMTOKENS and other subtypes of string. 1.0 returns NaN
.
floor(number)=> number
In 2.0, if argument is ()
, the result is ()
.
In 1.0, the result is NaN
. If compatibility mode is off, an
error will occur with more than one node. If compatibility mode is on,
implicit conversion is performed.
ceiling(number)=> number
In 2.0, if argument is ()
, the result is ()
.
In 1.0, the result is NaN
. If compatibility mode is off, an
error will occur with more than one node. If compatibility mode is on,
implicit conversion is performed.
round(number)=> number
In 2.0, if argument is ()
, the result is ()
.
In 1.0, the result is NaN
. If compatibility mode is off, an
error will occur with more than one node. If compatibility mode is on,
implicit conversion is performed.
Illustrative Userwritten Functions
Certain functions that were proposed for inclusion in this function library have
been excluded on the basis that it is straightforward for users to implement these
functions themselves using XSLT 2.0 or XQuery 1.0.
This Appendix provides sample implementations of some of these functions.
To emphasize that these functions are examples of functions that vendors may write,
their names carry the prefix 'eg'. Vendors are free to define such functions in any
namespace. A group of vendors may also choose to create a collection of such useful
functions and put them in a common namespace.
eg:ifempty and eg:ifabsent
In some situations, users may want to provide default values for missing
information that may be signaled by elements that are omitted, have no value or
have the empty sequence as their value. For example, a missing middle initial
may be indicated by omitting the element or a nonexistent bonus signaled with
an empty sequence. This section includes examples of functions that provide such
defaults. These functions return xdt:anyAtomicType*
. Users may want
to write functions that return more specific types.
eg:ifempty
If the first argument is the empty sequence or an element without simple or
complex content, ifempty() returns the second argument; otherwise, it
returns the content of the first argument.
XSLT implementation
<xsl:function name="eg:ifempty" as="xdt:anyAtomicType*">
<xsl:param name="node" as="node()?"/>
<xsl:param name="value" as="xdt:anyAtomicType"/>
<xsl:choose>
<xsl:when test="$node and $node/child::node()">
<xsl:sequence select="fn:data($node)"/>
</xsl:when>
<xsl:otherwise>
<xsl:sequence select="$value"/>
</xsl:otherwise>
</xsl:choose>
</xsl:function>
XQuery implementation
declare function eg:ifempty (
$node as node()?,
$value as xdt:anyAtomicType) as xdt:anyAtomicType*
{
if ($node and $node/child::node())
then fn:data($node)
else $value
}
eg:ifabsent
If the first argument is the empty sequence, ifabsent() returns the second
argument; otherwise, it returns the content of the first argument.
XSLT implementation
<xsl:function name="eg:ifabsent">
<xsl:param name="node" as="node()?"/>
<xsl:param name="value" as="xdt:anyAtomicType"/>
<xsl:choose>
<xsl:when test="$node">
<xsl:sequence select="fn:data($node)"/>
</xsl:when>
<xsl:otherwise>
<xsl:sequence select="$value"/>
</xsl:otherwise>
</xsl:choose>
</xsl:function>
XQuery implementation
declare function eg:ifabsent (
$node as node()?,
$value as xdt:anyAtomicType) as xdt:anyAtomicType*
{
if ($node)
then fn:data($node)
else $value
}
union, intersect and except on sequences of values
eg:valueunion
This function returns a sequence containing all the distinct items in $arg1
and $arg2, in an undefined order.
XSLT implementation
xsl:function name="eg:valueunion" as="xdt:anyAtomicType*">
<xsl:param name="arg1" as="xdt:anyAtomicType*"/>
<xsl:param name="arg2" as="xdt:anyAtomicType*"/>
<xsl:sequence
select="fn:distinctvalues(($arg1, $arg2))"/>
</xsl:function>
XQuery implementation
declare function eg:valueunion (
$arg1 as xdt:anyAtomicType*,
$arg2 as xdt:anyAtomicType*) as xdt:anyAtomicType*
{
fn:distinctvalues(($arg1, $arg2))
}
eg:valueintersect
This function returns a sequence containing all the distinct items that
appear in both $arg1 and $arg2, in an undefined order.
XSLT implementation>
<xsl:function name="eg:valueintersect" as="xdt:anyAtomicType*">
<xsl:param name="arg1" as="xdt:anyAtomicType*"/>
<xsl:param name="arg2" as="xdt:anyAtomicType*"/>
<xsl:sequence
select="fn:distinctvalues($arg1[.=$arg2])"/>
</xsl:function>
XQuery implementation
declare function eg:valueintersect (
$arg1 as xdt:anyAtomicType*,
$arg2 as xdt:anyAtomicType* ) as xdt:anyAtomicType*
{
fn:distinctvalues($arg1[.=$arg2])
}
eg:valueexcept
This function returns a sequence containing all the distinct items that
appear in $arg1 but not in $arg2, in an undefined order.
XSLT implementation
<xsl:function name="eg:valueexcept" as="xdt:anyAtomicType*">
<xsl:param name="arg1" as="xdt:anyAtomicType*"/>
<xsl:param name="arg2" as="xdt:anyAtomicType*"/>
<xsl:sequence
select="fn:distinctvalues($arg1[not(.=$arg2)])"/>
</xsl:function>
XQuery implementation
declare function eg:valueexcept (
$arg1 as xdt:anyAtomicType*,
$arg2 as xdt:anyAtomicType*) as xdt:anyAtomicType*
{
fn:distinctvalues($arg1[not(.=$arg2)])
}
eg:indexofnode
This function returns a sequence of positive integers giving the positions within
the sequence $seqParam
of nodes that are identical to $srchParam
.
The nodes in the sequence $seqParam
are compared with
$srchParam
under the rules for the is
operator. If a
node compares identical, then the position of that node in the sequence
$srchParam
is included in the result.
If the value of $seqParam
is the empty sequence, or if no node in
$seqParam
matches $srchParam, then the empty sequence is returned.
The index is 1based, not 0based.
The result sequence is in ascending numeric order.
XSLT implementation
<xsl:function name="eg:indexofnode" as="xs:integer*">
<xsl:param name="sequence" as="node()*"/>
<xsl:param name="srch" as="node()"/>
<xsl:foreach select="$sequence">
<xsl:if test=". is $srch">
<xsl:sequence select="position()"/>
</xsl:if>
</xsl:foreach>
</xsl:function>
XQuery implementation
declare function eg:indexofnode($sequence as node()*, $srch as node()) as xs:integer*
{
for $n at $i in $sequence where ($n is $srch) return $i
}
eg:stringpad
Returns a xs:string
consisting of a given number of copies of an
xs:string
argument concatenated together.
XSLT implementation
<xsl:function name="eg:stringpad" as="xs:string">
<xsl:param name="padString" as="xs:string?"/>
<xsl:param name="padCount" as="xs:integer"/>
<xsl:sequence select="fn:stringjoin((for $i in 1 to $padCount
return $padString), '')"/>
</xsl:function>
XQuery implementation
declare function eg:stringpad (
$padString as xs:string?,
$padCount as xs:integer) as xs:string
{
fn:stringjoin((for $i in 1 to $padCount return $padString), "")
}
This returns the zerolength string if $padString
is the empty
sequence, which is consistent with the general principle that if an
xs:string
argument is the empty sequence it is treated as if it
were the zerolength string.
eg:distinctnodesstable
This function illustrates one possible implementation of a distinctnodes
function. It removes duplicate nodes by identity, preserving the first
occurrence of each node.
XPath
$arg[empty(subsequence($arg, 1, position()1) intersect .)]
XSLT implementation
<xsl:function name="eg:distinctnodesstable" as="node()*">
<xsl:param name="arg" as="node()*"/>
<xsl:sequence
select="$arg[empty(subsequence($arg, 1, position()1) intersect .)]"/> </xsl:function>
XQuery implementation
declare function distinctnodesstable ($arg as node()*) as node()*
{
for $a at $apos in $arg
let $before_a := fn:subsequence($arg, 1, $apos  1)
where every $ba in $before_a satisfies not($ba is $a)
return $a
}
Schema for the XDT Namespace
The following schema defines the types in the
xdt:
namespace identified by the namespace name
http://www.w3.org/2005/xpathdatatypes
.
You can retrieve the normative schema for this namespace from
http://www.w3.org/2005/xpathdatatypes .
<?xml version='1.0'?>
<!
This document provides an XML Schema for xdt:dayTimeDuration and
xdt:yearMonthDuration.
The other xdt: types are not described here because xdt:untyped and
xdt:anyAtomicType are special types that cannot be properly defined
using XML Schema itself and because xdt:untypedAtomic should not be
used for validation, but only used for unvalidated elements and
attributes.
>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.w3.org/2005/xpathdatatypes"
xmlns:xdt="http://www.w3.org/2005/xpathdatatypes"
elementFormDefault="qualified"
blockDefault="#all"
xml:lang="en">
<xs:simpleType name='dayTimeDuration'>
<xs:annotation>
<xs:documentation
source="http://www.w3.org/TR/xpathdatamodel/#xdtdayTimeDuration"/>
</xs:annotation>
<xs:restriction base='xs:duration'>
<xs:pattern value="[^YM]*[DT].*"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name='yearMonthDuration'>
<xs:annotation>
<xs:documentation
source="http://www.w3.org/TR/xpathdatamodel/#xdtyearMonthDuration"/>
</xs:annotation>
<xs:restriction base='xs:duration'>
<xs:pattern value="[^DT]*"/>
</xs:restriction>
</xs:simpleType>
</xs:schema>
Checklist of ImplementationDefined Features
This appendix provides a summary of features defined in this specification whose effect is explicitly . The conformance rules require vendors to provide documentation that explains how these choices have been exercised.
The destination of the trace output is . See .
For xs:integer
operations, implementations that support limitedprecision integer operations either raise an error
or provide an mechanism that allows users to choose between raising an error and returning a result that is modulo the largest representable integer value. See .
For xs:decimal
values the number of digits of precision returned by the numeric operators is . See . See also
and
If the number of digits in the result of a numeric operation exceeds the number of digits that the implementation supports, the result is truncated or rounded in an manner. See . See also
and
It is which version of Unicode is supported by the features defined in this specification, but it is recommended that the most recent version of Unicode be used. See .
For , conforming implementations support normalization form "NFC" and support normalization forms "NFD", "NFKC", "NFKD", "FULLYNORMALIZED". They also support other normalization forms with semantics.
The ability to decompose strings into collation units suitable for substring matching is an property of a collation. See .
All minimally conforming processors support year values with a minimum of 4 digits (i.e., YYYY) and a minimum fractional second precision of 1 millisecond or three digits (i.e., s.sss). However, conforming processors set larger limits on the maximum number of digits they support in these two situations. See .
Various aspects of the processing provided by are . Implementations may provide external configuration options that allow any aspect of the processing to be controlled by the user.