Additionally, each facet definition element can be uniquely
addressed via a URI constructed as follows:
the base URI is the URI of the XML Schema namespace
the fragment identifier is the name of the facet
For example, to address the usage of the maxInclusive facet in
the definition of int, the URI is:
http://www.w3.org/2001/XMLSchema#int.maxInclusive
Primitive Datatypes
The datatypes defined by this specification
are described below. For each datatype, the
is described;
and
the
areis
defined,
using
an extended Backus Naur Format grammar
(and in most cases also a regular expression using the
regular expression language of
);
s which apply
to the datatype are listed;
and any datatypes
from this datatype are specified.
Primitive
datatypes can only be added by revisions
to this specification.
string
The string datatype
represents character strings in XML.
The
of string is the set of finite-length sequences of
characters (as defined in
) that the
Char production from .
A character is an atomic unit of
communication; it is not further specified except to note that every
character has a corresponding
Universal Character Set code point, which is an integer.
Many human languages have writing systems that require
child elements for control of aspects such as bidirectional formatting or
ruby annotation (see and Section 8.2.4
Overriding the
bidirectional algorithm: the BDO element of ).
Thus, string, as a simple type that can contain only
characters but not child elements, is often not suitable for representing text.
In such situations, a complex type that allows mixed content should be considered.
For more information, see Section 5.5
Any
Element, Any Attribute of .
As noted in , the fact that this specification does
not specify an
order relation
for order
for
does not preclude other applications from treating
strings
as being ordered.
Value Space
The
of is the set of finite-length sequences of
characters (as defined in
) that the
Char production from .
A character is an atomic unit of
communication; it is not further specified except to note that every
character has a corresponding
Universal Character Set (UCS) code point, which is an integer.
Equality for is
identity. No order is prescribed.
As noted in , the fact that this specification does
not specify an
order relation
for order
for
does not preclude other applications from treating
strings
as being ordered.
Lexical Mapping
The &lexical_space; of is the set of
finite-length sequences of
characters (as defined in
) that the
Char production from .
Lexical Space
stringRep
Char* (as defined in )
This is equivalent
to the regular expression (\s|\S)*, which
allows zero or more occurrences of any character in class s
or not in class s, i.e. any spacing or non-spacing character.
(It is also equivalent to (\c|\C)* or to any similar
expression created using any regular expression and its complement.)
Note that the regular expression .* does not match
all strings, since . does not match newline or linefeed.
The lexical mapping and canonical mapping
for are each the identity function:
The lexical mapping
for is , and
the canonical mapping is ;
each is a subset of the identity function.
Constraining facets
Facets
Derived
datatypesConstructed and
Immediately Derived
s
boolean
boolean
has the
required to support the mathematical
concept of binary-valued logic: {true,
false}represents the
values of two-valued logic.
Value Space
has the of
two-valued logic: {true, false}.
Lexical representation
An instance of a datatype that is defined as
can have the following legal literals {true, false, 1, 0}.
Canonical representation
The canonical representation for boolean is the set of
literals {true, false}.
Lexical Mapping
's lexical space is a set of four &strings;:
Lexical Space
booleanRep
true | false |
1 | 0
The lexical mapping and canonical mapping
for are the following functions:
The lexical mapping
for is ;
the canonical mapping is .
Constraining facets
Facets
&Odec;
RQ-150 (minimum number of digits for decimal)
The minimum number of digits implementations are required to support
will be lowered to 16 digits; a health warning will be added to note
that implementations of derived datatypes may support more digits of
precision than the base decimal type does, but that they are not required
to do so.
&odec;
represents
athat
subset of the real numbers, which
can be represented by
(finite-length) decimal numerals.
The of &odec;
is the set of numbers that can be obtained by
multiplyingdividing
an integer by a non-positivenegative
power of ten, i.e., expressible as
i × 10^-ni / 10n
where i and n are integers
and
n >= 0n ≥ 0.
Precision is not reflected in this value space;
the number 2.0 is not distinct from the number 2.00.
(The datatype may be used
for values in which precision is significant.)
The order relation on &odec;
is the order relation on real numbers, restricted
to this subset.
All processors
support &odec; numbers with a minimum of
1816 decimal digits
(i.e., with a
of 18they
must support all values which would be
allowed by a which set
to 16). However,
processors set
an application-defined limit on the maximum number of decimal digits
they are prepared to support, in which case that application-defined
maximum number be clearly documented.
Value Space
The of
is the set of numbers that can be obtained by
dividing an integer by a non-negative
power of ten, i.e., expressible as
i / 10n
where i and n are integers
and n ≥ 0 .
Precision is not reflected in this value space;
the number 2.0 is not distinct from the number 2.00.
(The datatype may be used
for values in which precision is significant.)
See the conformance note in , which
applies to this datatype.
The equality relation on is the identity.
The order relation is the usual order relation on real numbers, restricted
to this subset.
Lexical
representationMapping
&odec;
has a lexical representation
consisting of a finite-length sequence of decimal digits (#x30–#x39) separated
by a period as a decimal indicator.
An optional leading sign is allowed.
If the sign is omitted,
"+"+
is assumed. Leading and trailing zeroes are optional.
If the fractional part is zero, the period and following zero(es) can
be omitted.
For example:
-1.23, 12678967.543233, +100000.00,
210-1.23,
12678967.543233, +100000.00,
210.
The Lexical Representation
&odec;LexicalRep
|
The lexical space of &odec; is the set of
lexical representations which match the grammar given above, or
(equivalently) the regular expression
-(+|-)?(([0-9]+(.[0-9]*)?)|(.[0-9]+)).
The mapping from lexical representations to values is the usual
one for decimal numerals; it is given formally in:
The mapping from lexical representations to values is the usual
one for decimal numerals; it is given formally in
.
The following paragraphs were
moved from the deleted section that follows into this one to align the
organization of this datatype description with that of others that are
newly rewritten for 1.1.
The canonical representation for
&odec; is defined by prohibiting certain options from the
.
Specifically, the preceding optional
"+"+
sign is prohibited. The
decimal point is required. Leading and trailing zeroes are
prohibited subject to the following: there must be at least one
digit to the right and to the left of the decimal
point, which may be a zero.
The mapping from values to canonical representations
is given formally in:
The mapping from values to canonical representations
is given formally in
.
Canonical representation
The canonical representation for &odec; is defined by
prohibiting certain options from the
.
Specifically, the preceding optional
"+"+
sign is prohibited. The decimal point is required. Leading
and trailing zeroes are prohibited subject to the following: there
must be at least one digit to the right and to the left of the decimal
point, which may be a zero.
The mapping from values to canonical representations
is given formally in:
The mapping from values to canonical representations
is given formally in
.
Simple Type Definition for &odec;
The of is present in every
schema. It has the following properties:
of
&odec;
http://www.w3.org/2001/XMLSchema
The
The empty set
atomic
{a facet with
= collapse}
{
an facet
with = total
a facet
with = false
a facet
with = countable
a facet
with = true
global
absent
absent
The empty sequence
Constraining facets
Facets
Derived datatypesDatatypes based on &odec;
&pD;
The &pD;
datatype represents decimal numbers, together
with their (arithmetic) precisionthe
numeric value and (arithmetic) precision of decimal numbers which retain
precision; it also
includes special values for positive and negative infinity and
not a number, and it differentiates
between positive zero and negative
zero. The special values are
introduced to make the datatype correspond closely to
decimal datatypes
whose definition is planned for the
next revision of IEEE/ANSI 754the
floating-point decimal datatypes described by the forthcoming
revision of IEEE/ANSI 754.
Precision is sometimes given in absolute, sometimes in relative
terms. The arithmetic precision of a value is
expressed in absolute quantitative terms,
by indicating
how many digits to the right of the decimal point are significant.
5
has an arithmetic precision of 0, and
5.01
an arithmetic precision of 2.
All processors
&must; support all values
in the &value_space; of the
otherwise unconstrained
datatype for which
is set to sixteen, to 369,
and to −398.
Note: The conformance limits given in the text correspond to those
of the decimal64 type defined in the current draft of IEEE 754R, which
can be stored in a 64-bit field. The XML Schema Working Group
recommends that implementors support limits corresponding to those of
the decimal128 type. This entails supporting the values in the value
space of the otherwise unconstrained datatype for which
is set to 34, to 6176,
and to −6111.
The XML Schema Working Group requests feedback from implementors
and users of XML Schema concerning the minimum and recommended
implementation limits for . If other
limits, larger or smaller, would make this dataytpe more attractive to
users or implementors, please let us know.
Value Space
Properties of
Values
numericalValue
a &decimal;, positiveInfinity,
negativeInfinity or notANumber
arithmeticPrecision
an &integer; or absent;
absent if and only if is a .
sign
positive, negative, or absent;
must be positive if
is positive or positiveInfinity, must be negative
if is negative or negativeInfinity,
must be absent if and only if is notANumber
The property is redundant except when
is zero; in other cases, the value is fully determined by the
value.
Code optimization may well make it desirable to separate out the
and the absolute value of the
, which will make implementation easier,
but the verbal descriptions of such things as equality
and order somewhat more complicated.
As explained below, the lexical
representation of the value object whose
is notANumber is NaN. Accordingly, in English text we
use NaN to refer to that value. Similarly we use INF
and −INF to refer to the two value objects whose
is positiveInfinity and negativeInfinity. These three value objects
are also informally called not-a-number
, positive infinity
,
and negative infinity
.
The latter two together are called
the infinities
.
Equality and order for are defined as follows:
-
Two numerical values
are ordered (or equal) as their
values are ordered (or equal).
(This means
thethat
two zeros with a given
but
different s
are equal;
negative zeros are not ordered less than positive zeros.)
-
A numerical value n
is less than, equal to, or greater than
and a value v other than INF, -INF, or NaN
as n is less than, equal to, or greater than
the of v.
(This comparison is necessary when comparing
values to upper and lower bounds.)
-
INF is equal only to itself, and is greater than
−INF and all numerical values.
-
−INF is equal only to itself, and is less than
INF and all numerical values.
NaN is incomparable with all values, including
itself.
Lexical Mapping
's lexical space is the set of all
decimal numerals with or without a decimal
point, numerals in scientific (exponential) notation, and
the character strings INF,
+INF, -INF,
and NaN.
The
facet can remove any one or two of the three subsets of
numerals, with corresponding reductions in
the value space. Using this facet
rather than will change the canonical
mapping to insure that the resulting datatype will still have canonical
representations of all its values.
Lexical Space
precisionDecimalRep
| |
|
The lexical mapping and canonical mapping
for are the following functions:
The lexical mapping for
is . The
canonical mapping is .
Simple Type Definition for &pD;
The of is present in every
schema. It has the following properties:
of
&pD;
http://www.w3.org/2001/XMLSchema
The
The empty set
atomic
{
a facet with
= collapse and
= true
-
a facet with the value
{nodecimal, decimal, scientific}
}
{
an facet
with = total
a facet
with = false
a facet
with = countable
a facet
with = true
global
absent
absent
The empty sequence
&CFacet;s
Facets
float
RQ-1 (canonical
representation of float, double)
The description of canonical representations for float and double
needs to be cleaned up.
RQ-140
(positive and negative zero in float and double)
Two zeros will be provided similar to those in precisionDecimal
The
float datatype
is patterned after the IEEE
single-precision 32-bit floating point datatype
with the minor exception
noted below. The
basic of
float consists of the values
m × 2^evalues
of float are the non-zero numbers
m × 2e,
where m
is an integer whose absolute value is less than
2^24224, and e is an integer
between -149 and 104, inclusive. In addition to the basic
values described above, the
of float also contains the
following three
special values: positive and negative zero,
positive and negative infinity,
and not-a-number (NaN).
The
order
relation on float
is: x < y iff y - x is positive
for x and y in the value space.
For the basic values, the order relation
on float is the usual one for rational numbers.
Positive infinity is greater than all other non-NaN
values.;
negative infinity is less than all other non-NaN values.
NaN equals itself but is incomparable with (neither greater than nor less than)
any other value in the .
Positive and negative zero are greater than
all the negative numbers among the basic values and less than all the
positive numbers. They are distinct values
which compare equal. (They are thus distinct for purposes of enumerations
and identity constraints, and equal for purposes of minimum and maximum
values.)
Floating point numbers are certain subsets of the rational numbers, and are often used to
approximate arbitrary real numbers.
"Equality" in this Recommendation is defined to be "identity" (i.e.,
values that are identical in the are
equal and vice versa). Identity must be used for the few operations
that are defined in this Recommendation. Applications using any of the
datatypes defined in this Recommendation may use different definitions
of equality for computational purposes;
-based computation systems are examples. Nothing in
this Recommendation should be construed as requiring that such
applications use identity as their equality relationship when
computing.
Any value incomparable with the value used for the four bounding facets
(, ,
, and ) will be
excluded from the resulting restricted . In particular,
when "NaN" is used as a facet value for a bounding facet, since no other
float values are
comparable with it,
the result is a
either having NaN as its only member (the inclusive cases) or that is empty
(the exclusive cases). If any other value is used for a bounding facet,
NaN will be excluded from the resulting restricted ;
to add NaN back in requires union with the NaN-only space.
This datatype differs from that of in that there is only one
NaN and only one zero.
This makes the equality and ordering of values in the data
space differ from that of only
in that for schema purposes NaN = NaN.
A &literal; in the representing a
decimal number d maps to the normalized value
in the of float that is
closest to d in the sense defined by
; if d is
exactly halfway between two such values then the even value is chosen.
Value Space
The of contains the
non-zero numbers m × 2e ,
where m is an integer whose absolute value is less than 224,
and e is an integer between −149 and 104, inclusive. In addition to
these values, the of also contains
the following special values: positiveZero,
negativeZero, positiveInfinity,
negativeInfinity, and notANumber.
As explained below, the of the
value notANumber is NaN. Accordingly, in English
text we generally use NaN to refer to that value. Similarly,
we use INF and −INF to refer to the two
values positiveInfinity and negativeInfinity,
and 0 and −0 to refer to
positiveZero and negativeZero.
Equality and order for are defined as follows:
-
Equality is identity, except that 0 = −0 (although
they are not identical) and NaN ≠ NaN
(although NaN is of course identical to itself).
0 and −0 are thus distinct for purposes of enumerations and
identity constraints, but equal for purposes of minimum and maximum values.
-
For the basic values, the order relation
on float is the order relation for rational numbers. INF is greater
than all other non-NaN values; −INF is less than all other non-NaN
values. NaN is with any value
in the including itself. 0 and −0
are greater than all the negative numbers and less than all the positive
numbers.
Any value with the value used for the four
bounding facets (, ,
, and ) will be
excluded from the resulting restricted .
In particular, when NaN is used as a facet value for a bounding facet, since no
values are comparable
with it, the result is a that is empty.
If any other value is used for a bounding facet,
NaN will be excluded from the resulting restricted ;
to add NaN back in requires union with the NaN-only space (which may be derived
by an enumeration).
The Schema 1.0 version of this datatype did not differentiate between
0 and −0 and NaN was equal to itself. The changes were
made to make the datatype more closely mirror .
Lexical representation
float values have a lexical representation
consisting of a mantissa followed, optionally, by the character
E or e,
followed by an exponent. The exponent
be an . The mantissa must be a
number. The representations
for exponent and mantissa must follow the lexical rules for
and . If the
E or e and
the following exponent are omitted, an exponent value of 0 is assumed.
The special values
positive
and negative infinity and not-a-number have lexical representations
INF, -INF and
NaN, respectively.
Lexical representations for zero may take a positive or negative sign.
For example, -1E4, 1267.43233E12, 12.78e-2, 12
, -0, 0
and INF are all legal &literals; for float.
Canonical representation
The canonical representation for float is defined by
prohibiting certain options from the
. Specifically, the exponent
must be indicated by "E". 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 non-zero
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. The canonical
representation for zero is 0.0E0.
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 float
is a mantissa, which is a decimal, followed by E
followed by an exponent which is an 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 non-zero 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. The canonical form of
positive zero is 0.0E0. The canonical form for negative zero
is -0.0E0. 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.
Lexical Mapping
The of is
the set of all decimal numerals with or without a decimal
point, numerals in scientific (exponential) notation, and
the literals INF,
-INF, and NaN
Lexical Space
floatRep
| |
|
The production is equivalent to this regular expression:
(-|+)?(([0-9]+(.[0-9]*)?)|(.[0-9]+))((e|E)(-|+)?[0-9]+)?|-?INF|NaN
The datatype is designed to implement for schema
processing the single-precision floating-point datatype of
. That specification does not specify specific
lexical representations,
but does prescribe requirements on any
used. Any
that maps the just described onto the
, satisfies the requirements of
, and correctly handles the special values
( literals),
satisfies the conformance requirements of this specification.
Since IEEE allows some variation in rounding of values, processors
conforming to this specification may exhibit some variation in their
lexical mappings.
The is
provided as an example of a simple algorithm that yields a conformant mapping,
and that provides the most accurate rounding possible—and is thus useful
for insuring inter-implementation reproducibility and inter-implementation
round-tripping. The simple rounding
algorithm used in may be more efficiently
implemented using the algorithms of .
The Schema 1.0 version of this datatype did not permit rounding
algorithms whose results differed from .
The is
provided as an example of a mapping that does not produce unnecessarily long
canonical representations.
Other algorithms which do not yield identical results for mapping from float
values to character strings are permitted by .
Constraining facets
Facets
double
The double
datatype is patterned after the
IEEE double-precision 64-bit floating point datatype
with the minor exception
noted below.
The basic
of double consists of the values
m × 2^e, The
basic values of double are the non-zero numbers
m × 2e,
where m
is an integer whose absolute value is less than
253, and e is an
integer between -1075 and 970, inclusive. In addition to the basic
values described above, the
of double also contains
the following
three
special values:
positive and negative zero,
positive and negative infinity,
and not-a-number
(NaN).
The
order relation on double
is: x < y iff y - x is positive
for x and y in the value space.
For the basic values, the order relation
on double is the usual one for rational numbers.
Positive infinity is greater than all other non-NaN
values.;
negative infinity is less than all other non-NaN values.
NaN equals itself but is incomparable with (neither greater than nor less than)
any other value in the .
Positive and negative zero are greater than
all the negative numbers among the basic values and less than all the
positive numbers. They are distinct values
which compare equal. (They are thus distinct for purposes of enumerations
and identity constraints, and equal for purposes of minimum and maximum
values.)
Floating point numbers are certain subsets of the rational numbers, and are often used to
approximate arbitrary real numbers.
The only significant differences between float and double are
the three defining constants 53 (vs 24), −1074 (vs −149),
and 971 (vs 104).
"Equality" in this Recommendation is defined to be "identity" (i.e.,
values that are identical in the are
equal and vice versa). Identity must be used for the few operations
that are defined in this Recommendation. Applications using any of the
datatypes defined in this Recommendation may use different definitions
of equality for computational purposes;
-based computation systems are examples. Nothing in
this Recommendation should be construed as requiring that such
applications use identity as their equality relationship when
computing.
Any value incomparable with the value used for the four bounding facets
(, ,
, and ) will be
excluded from the resulting restricted . In particular,
when "NaN" is used as a facet value for a bounding facet, since no other
double values are
comparable with it,
the result is a
either having NaN as its only member (the inclusive cases) or that is empty
(the exclusive cases). If any other value is used for a bounding facet,
NaN will be excluded from the resulting restricted ;
to add NaN back in requires union with the NaN-only space.
This datatype differs from that of in that
there is only one NaN and only one
zero. This makes the equality and ordering of values in the
data space differ from that of
only in that for schema purposes
NaN = NaN.
A &literal; in the representing a
decimal number d maps to the normalized value
in the of double that is
closest to d; if d is
exactly halfway between two such values then the even value is chosen.
This is the best approximation of d
(, ), which is more
accurate than the mapping required by .
Value Space
The of contains the
non-zero numbers m × 2e ,
where m is an integer whose absolute value is less than 257253,
and e is an integer between −1074 and 971, inclusive. In addition to
these values, the of also contains
the following special values: positiveZero,
negativeZero, positiveInfinity,
negativeInfinity, and notANumber.
As explained below, the of the
value notANumber is NaN. Accordingly, in English
text we generally use NaN to refer to that value. Similarly,
we use INF and −INF to refer to the two
values positiveInfinity and negativeInfinity,
and 0 and −0 to refer to
positiveZero and negativeZero.
Equality and order for are defined as follows:
-
Equality is identity, except that 0 = −0 (although
they are not identical) and NaN ≠ NaN
(although NaN is of course identical to itself).
0 and −0 are thus distinct for purposes of enumerations and
identity constraints, but equal for purposes of minimum and maximum values.
-
For the basic values, the order relation
on double is the order relation for rational numbers. INF is greater
than all other non-NaN values; −INF is less than all other non-NaN
values. NaN is with any value
in the including itself. 0 and −0
are greater than all the negative numbers and less than all the positive
numbers.
Any value with the value used for the four
bounding facets (, ,
, and ) will be
excluded from the resulting restricted .
In particular, when NaN is used as a facet value for a bounding facet, since no
values are comparable
with it, the result is a that is empty.
If any other value is used for a bounding facet,
NaN will be excluded from the resulting restricted ;
to add NaN back in requires union with the NaN-only space (which may be derived
by an enumeration).
The Schema 1.0 version of this datatype did not differentiate between
0 and −0 and NaN was equal to itself. The changes were
made to make the datatype more closely mirror .
Lexical representation
double values have a lexical representation
consisting of a mantissa followed, optionally, by the character "E" or
"e", followed by an exponent. The exponent be
an integer. The mantissa must be
a number. The representations
for exponent and mantissa must follow the lexical rules for
and
. If the E or e and
the following exponent are omitted, an exponent value of 0 is assumed.
The special values
positive
and negative infinity and not-a-number have lexical representations
INF, -INF and
NaN, respectively.
Lexical representations for zero may take a positive or negative sign.
For example, -1E4, 1267.43233E12, 12.78e-2, 12
, -0, 0
and INF
are all legal &literals; for double.
Canonical representation
The canonical representation for double is defined by
prohibiting certain options from the
. Specifically, the exponent
must be indicated by "E". 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 non-zero
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. The canonical
representation for zero is 0.0E0.
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 double
is a mantissa, which is a decimal, followed by E
followed by an exponent which is an 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 non-zero 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. The canonical form of
positive zero is 0.0E0. The canonical form for negative zero
is -0.0E0. 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.
Lexical Mapping
The of is
the set of all decimal numerals with or without a decimal
point, numerals in scientific (exponential) notation, and
the literals INF,
-INF, and NaN
Lexical Space
doubleRep
| |
|
The production is equivalent to this regular expression:
(-|+)?(([0-9]+(.[0-9]*)?)|(.[0-9]+))((e|E)(-|+)?[0-9]+)?|-?INF|NaN
The datatype is designed to implement for schema
processing the double-precision floating-point datatype of
. That specification does not specify specific
lexical representations,
but does prescribe requirements on any
used. Any
that maps the just described onto the
, satisfies the requirements of
, and correctly handles the special values
( literals),
satisfies the conformance requirements of this specification.
Since IEEE allows some variation in rounding of values, processors
conforming to this specification may exhibit some variation in their
lexical mappings.
The is
provided as an example of a simple algorithm that yields a conformant mapping,
and that provides the most accurate rounding possible—and is thus useful
for insuring inter-implementation reproducibility and inter-implementation
round-tripping. The simple rounding
algorithm used in may be more efficiently
implemented using the algorithms of .
The Schema 1.0 version of this datatype did not permit rounding
algorithms whose results differed from .
The is
provided as an example of a mapping that does not produce unnecessarily long
canonical representations.
Other algorithms which do not yield identical results for mapping from float values
to character strings are permitted by .
Constraining facets
Facets
duration
duration represents a duration of time. The
of duration is a six-dimensional
space where the coordinates designate the Gregorian year, month, day,
hour, minute, and second components defined in § 5.5.3.2 of
, respectively. These components are ordered
in their significance by their order of appearance i.e. as year,
month, day, hour, minute, and second.
All processors
support year values with a minimum of 4 digits (i.e.,
YYYY) and a minimum fractional second precision of
milliseconds or three decimal digits (i.e. s.sss).
However, processors
set an application-defined limit on the maximum number
of digits they are prepared to support in these two cases, in which
case that application-defined maximum number
be clearly documented.
duration
is a datatype that represents
durations of time. The concept of duration being captured is
drawn from those of , specifically
durations without fixed endpoints. For example,
15 days (whose most common lexical representation
in is P15D
) is
a value; 15 days beginning 12 July
1995 and 15 days ending 12 July 1995 are
not. can provide addition and
subtraction operations between values and
between / value pairs,
and can be the result of subtracting
values. However, only addition to and
subtraction from
is required for XML Schema processing and is
defined in
in
the function .
The
The of is present in every
schema. It has the following properties:
of
duration
http://www.w3.org/2001/XMLSchema
The
The empty set
atomic
absent
{a facet}
TBD
TBD
absent
absent
The empty sequence
The facet in the
's
has the following properties:
Facet of the
collapse
false
The empty sequence
Value Space
Durations can be modeled in at least
two ways: as six-property tuples (similar to the seven-property model
used for other date/time datatypes) or as two-property tuples
(somewhat similar to the alternative one-property timeOnTimeline model
especially useful for order). For
durations, it is useful to use the latter:
values are two-property tuples. (Note, however, that the
six-property model was implicitly used in Schema 1.0. The only
effective difference to the user caused by this change is in the
canonical representations.) See
for more information on the
seven-property model.
Duration values can be modelled as
two-property tuples. Each value consists of an integer number of
months and a decimal number of seconds. The
value &mustnot; be negative if the
value is positive and &mustnot; be
positive if the is negative.
Properties of Values
months
seconds
a value;
Must
not&mustnot;
be negative if is positive, and
not&mustnot;
be positive if is negative.
is partially ordered.
Equality and order are defined in terms of
that of , and are determined by adding each
value pair in turn
toEquality of
is defined in terms of equality of ; order for
is defined in terms of the order of
. Specifically, the equality or order of
two values is determined by adding each
in the pair to each of the following
four values:
1696-09-01T00:00:00Z
1697-02-01T00:00:00Z
1903-03-01T00:00:00Z
1903-07-01T00:00:00Z
These four values are chosen so as to maximize
the possible differences in results that could occur,
such as the difference when adding P1M and P30D:
1697-02-01T00:00:00Z + P1M < 1697-02-01T00:00:00Z + P30D ,
but
1903-03-01T00:00:00Z + P1M > 1903-03-01T00:00:00Z + P30D ,
so that P1M <> P30D .
If two values are ordered the same way
when added to each of these four values,
they will retain the same order when added
to any other
values,
unless one is within a leap-second and either the other
is also or is the beginning moment of the next second—in which case,
the two results will be equal even though the original
values were not. Therefore,
two values are incomparable if and only
if they can ever result in different orders when added to any
value not
within a leap-second.
This minor anomaly is the result of having
unaware of leap-seconds while the other
date/time primitive datatypes are leap-second aware.
It turns out that
uUnder the definition just given,
two values are equal if and only if they are identical.
Two totally ordered datatypes ( and
) are derived from in
.
There are many ways to implement ,
some of which do not base the implementation on the two-component
model. This specification does not prescribe any particular
implementation, as long as the visible results are isomorphic to those
described herein.
Lexical representation
The lexical representation for duration is the
extended format PnYn
MnDTnH nMnS, where
nY represents the number of years, nM the
number of months, nD 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 number of seconds can include decimal digits
to arbitrary precision.
The values of the
Year, Month, Day, Hour and Minutes components are not restricted but
allow an arbitrary
unsigned
integer, i.e., an integer that
conforms to the pattern [0-9]+..
Similarly, the value of the Seconds component
allows an arbitrary unsigned decimal.
Following , at least one digit must
follow the decimal point if it appears. That is, the value of the Seconds component
must conform to the pattern [0-9]+(\.[0-9]+)?.
Thus, the lexical representation of
duration does not follow the alternative
format of § 5.5.3.2.1 of .
An optional preceding minus sign ('-') is
allowed, to indicate a negative duration. If the sign is omitted a
positive duration is indicated. See also .
For example, to indicate a duration of 1 year, 2 months, 3 days, 10
hours, and 30 minutes, one would write: P1Y2M3DT10H30M.
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 years, months, days, hours, minutes, or seconds in any
expression equals zero, 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' mustshall
be absent if and only if all of the time items are absent.
The designator 'P' must always be present.
For example, P1347Y, P1347M and P1Y2MT2H are all allowed;
P0Y1347M and P0Y1347M0D are allowed. P-1347M is not allowed although
-P1347M is allowed. P1Y2MT is not allowed.
Lexical Space
The lexical representations
of are
more or less based on the pattern:
PnYnMnDTnHnMnS
More precisely, the of
is the set of character
strings that satisfy as defined by the following productions:
Lexical Representation Fragments
duYearFrag
Y
duMonthFrag
M
duDayFrag
D
duHourFrag
H
duMinuteFrag
M
duSecondFrag
( | ) S
duYearMonthFrag
( ?) |
duTimeFrag
T (( ? ?) |
( ?) |
)
duDayTimeFrag
( ?) |
Lexical Representation
durationLexicalRep
-? P (( ?) | )
Thus, a consists of one or more of a ,
, , ,
, and/or , in order, with letters
P and T (and perhaps a -)
where appropriate.
The
production is equivalent
to this regular expression
-?P(((([0-9]+Y([0-9]+M)?)|
( ([0-9]+M) ) )(([0-9]+D(T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+(\.[0-9]+)?S) ) ))?)|
( (T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+(\.[0-9]+)?S) ) )) ) )?)|
( (([0-9]+D(T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+(\.[0-9]+)?S) ) ))?)|
( (T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+(\.[0-9]+)?S) ) )) ) ) ) )
once you delete the
whitespace. Redundant parentheses are shown as
ghosts; some find them helpful in reading the expression.)
The language accepted by the
production is the set of strings which satisfy all of the following
three regular expressions:
The expression
-?P([0-9]+Y)?([0-9]+M)?([0-9]+D)?(T([0-9]+H)?([0-9]+M)?((([0-9]+(.[0-9]*)?)|(.[0-9]+))S)?)? matches only strings in which the fields occur in the proper order.
The expression .*[YMDHS].* matches only
strings in which at least one field occurs.
The expression .*[^T] matches
only strings in which T is not the final character, so that
if T appears, something follows it. The first rule
ensures that what follows T will be an hour,
minute, or second field.
-?P(((([0-9]+Y([0-9]+M)?)|
( ([0-9]+M) ) )(([0-9]+D(T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+(\.[0-9]+)?S) ) ))?)|
( (T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+(\.[0-9]+)?S) ) )) ) )?)|
( (([0-9]+D(T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+(\.[0-9]+)?S) ) ))?)|
( (T(([0-9]+H([0-9]+M)?([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+M) ([0-9]+(\.[0-9]+)?S)?)|
( ([0-9]+(\.[0-9]+)?S) ) )) ) ) ) )
The
for is called
herein,
is defined as follows:.
The
lexical mapping for is .
Canonical mappings are not used during schema processing. They are
provided in this specification for the benefit of other users of these
datatype definitions
datatypes who may find them useful,
and for other specifications
which might find it useful to reference them normatively.
The canonical
mapping for is
called
herein,
is defined as follows:.
The canonical
mapping for
is .
Order relation on duration
In general, the on duration
is a partial order since there is no determinate relationship between certain
durations such as one month (P1M) and 30 days (P30D).
The
of two duration values x and
y is x < y iff s+x < s+y
for each qualified s
in the list below. These values for s cause the greatest deviations in the addition of
dateTimes and durations. Addition of durations to time instants is defined
in .
1696-09-01T00:00:00Z
1697-02-01T00:00:00Z
1903-03-01T00:00:00Z
1903-07-01T00:00:00Z
The following table shows the strongest relationship that can be determined
between example durations. The symbol <> means that the order relation is
indeterminate. Note that because of leap-seconds,
a seconds field can vary
from 59 to 60. However, because of the way that addition is defined in
, they are still totally ordered.
| |
Relation |
| P1Y |
> P364D |
<> P365D |
|
<> P366D |
< P367D |
| P1M |
> P27D |
<> P28D |
<> P29D |
<> P30D |
<> P31D |
< P32D |
| P5M |
> P149D |
<> P150D |
<> P151D |
<> P152D |
<> P153D |
< P154D |
Implementations are free to optimize the computation of the ordering relationship. For example, the following table can be used to
compare durations of a small number of months against days.
| |
Months |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
13 |
... |
| Days |
Minimum |
28 |
59 |
89 |
120 |
150 |
181 |
212 |
242 |
273 |
303 |
334 |
365 |
393 |
... |
| Maximum |
31 |
62 |
92 |
123 |
153 |
184 |
215 |
245 |
276 |
306 |
337 |
366 |
397 |
... |
Facet Comparison for durations
In comparing duration
values with , ,
and facet values,
indeterminate comparisons should be considered as "false".
Totally ordered durations
Certain derived datatypes of durations can be guaranteed have a total order. For
this, they must have fields from only one row in the list below and the time zone
must either be required or prohibited.
year, month
day, hour, minute, second
For example, a datatype could be defined to correspond to the
datatype Year-Month interval that required a four digit
year field and a two digit month field but required all other fields to be unspecified. This datatype could be defined as below and would have a total order.
]]>
&CFacet;s
Facets
Related Datatypes
dateTime
dateTime values
may be viewed as objects with integer-valued
year, month, day, hour and minute properties,
a decimal-valued second property,
and a boolean timezoned property.
Each such object also has one decimal-valued
method or computed property, timeOnTimeline,
whose value is always a decimal
number; the values are dimensioned in seconds,
the integer 0 is 0001-01-01T00:00:00 and the value
of timeOnTimeline for other dateTime
values is computed using the Gregorian algorithm
as modified for leap-seconds.
The timeOnTimeline values form two related
"timelines", one for timezoned
values and one for non-timezoned values.
Each timeline is a copy of the
of ,
with integers given units of seconds.
represents
instants of time, optionally marked
with a particular timezone. Values representing
the same instant but having
different timezones are equal but not
identical.
The of
dateTime is closely related
to the dates and times described in ISO 8601.
For clarity, the text above specifies a
particular origin point for the timeline.
It should be noted, however, that schema processors need not expose the
timeOnTimeline value to schema users, and there is no requirement that a
timeline-based implementation use the particular origin described here in
its internal representation.
Other interpretations of the which lead to the
same results (i.e., are isomorphic) are of course acceptable.
All timezoned times are Coordinated Universal Time
(, sometimes called
"Greenwich Mean Time").
Universal
Coordinated Time
(UTC) is an adaptation of International Atomic Time (TAI)
which closely approximates observed astronomical time by adding
leap-seconds to
selected days.
A
leap-second is an additional second added
to the last day of December, June, October, or March,
when such an adjustment is deemed necessary by the
International Earth Rotation and Reference Systems Service
in order to keep within 0.9 seconds
of observed astronomical time. When leap seconds are
introduced, the last minute in the day has more than
sixty seconds.
In theory leap seconds can also be removed from a
day, but this has not yet occurred.
Other timezones indicated in lexical representations
are converted to
during conversion of literals to values.
"Local" or untimezoned times are presumed to be
the time in the timezone of some
unspecified locality as prescribed
by the appropriate legal authority;
currently there are no legally prescribed
timezones which are durations
whose magnitude is greater than 14 hours.
The value of each numeric-valued property
(other than timeOnTimeline) is limited to
the maximum value within the interval
determined by the next-higher property.
For example, the day value can never be 32,
and cannot even be 29 for month 02 and year 2002 (February 2002).
The date and time datatypes described in this recommendation were inspired
by . '0001' is the lexical
representation of the year 1 of the Common Era
(1 CE, sometimes written "AD 1" or "1 AD"). There
is no year 0, and '0000' is not a valid lexical representation.
'-0001' is the lexical representation of the year 1 Before
Common Era (1 BCE, sometimes written "1 BC").
Those using this (1.0) version of this Recommendation to
represent negative years should be aware that the interpretation of lexical
representations beginning with a '-' is likely to change in
subsequent versions.
makes no mention of the year 0; in
the form '0000' was disallowed and this recommendation disallows it as well.
However, , which became
available just as we were completing version
1.0, allows the form '0000', representing the year
1 BCE. A number of external commentators
have also suggested that '0000' be
allowed, as the lexical representation for 1 BCE,
which is the normal usage in
astronomical contexts.
It is the intention of the XML Schema
Working Group to allow '0000' as a lexical representation in the
dateTime, date, gYear, and
gYearMonth datatypes in a subsequent version
of this Recommendation. '0000' will be the lexical representation of 1
BCE (which is a leap year), '-0001' will become the lexical representation of 2
BCE (not 1 BCE as in this (1.0) version), '-0002' of 3 BCE, etc.
See the conformance note in
which applies to this datatype as well.
Value Space
uses the
, with no properties
except
permitted
to be absent. The property remains
.
In version 1.0 of this specification, the
property was not permitted to have the value
zero. The year 1 BCE was represented by a
value of −1, 2 BCE by −2, and so
forth. In this version of this specification,
two changes are made in order to agree with existing usage.
First, is permitted to have the value zero.
Second, the interpretation of
values is changed accordingly: a value of zero represents 1 BCE, −1
represents 2 BCE, etc. This representation simplifies interval
arithmetic and leap-year calculation for dates before the common era.
Note that 1 BCE, 5 BCE, and so on (years 0000, -0004, etc. in the
lexical representation defined here) are leap years in the proleptic
Gregorian calendar used for the date/time datatypes defined here.
Version 1.0 of this specification was unclear about the treatment of
leap years before the common era; caution should be used if existing
schemas or data specify dates of 29 February for any years before the
common era. With that possible exception, schemas and data valid
under the old interpretation remain valid under the new.
Day-of-month Values
The value
&must; be
no more than 30 if
is one of 4, 6, 9, or 11;
no more than 28
if is 2 and
is not divisible 4,
or is divisible by 100 but not by 400;
and no more than 29 if
is 2 and
is divisible by 400, or by 4 but not by 100.
Leap-second Values
The value
&must; be
less than 60 if
is absent or if the remaining values
do not correspond to a dateTime
at which a leap-second was introduced into
by the responsible authorities;
if the
hour and minute in the specified timezone
allow a real leap-second then the value
&must; be less than or equal to 60 plus the number of
leap-seconds introduced on that date. (At
the time of publication of this specification, no
more than one leap-second has ever been introduced at
a timeand it appears unlikely that
this will ever happen.
No negative leap-seconds have been
introduced, but if any should be introduced in future,
adding that negative number will result
in a value limit of 59 or lower.)
See the conformance note in
which applies to the and
values of this datatype.
Equality and order are as prescribed
in .
values are ordered
by their value.
Since the order of a
value having a
with another value whose
is absent is determined
by imputing timezones of both +14:00
and −14:00 to the untimezoned value, many such
combinations will be
because the two imputed
timezones yield different orders.
Although and other
types related to dates and times have only a partial order, it
is possible for datatypes derived from to have
total orders, if they are restricted (e.g. using the
facet) to the subset of values with, or
the subset of values without, timezones. Similar restrictions
on other date- and time-related types will similarly produce
totally ordered subtypes. Note, however, that
such restrictions do not affect the value shown, for a given
, in the facet.
Order and equality are essentially the same for
in this version of this specification as
they were in version 1.0. However, since values
now distinguish timezones, equal
values with different s
are not identical, and values with extreme
s may no longer be equal
to any value with a smaller .
Lexical representation
The of dateTime consists of
finite-length sequences of characters of the form:
'-'? yyyy '-' mm '-' dd 'T' hh ':' mm ':' ss ('.' s+)? (zzzzzz)?,
where
'-'? yyyy is a
four-or-more digit optionally negative-signed
numeral that represents the year; if more than four digits, leading zeros
are prohibited, and '0000' is prohibited
(see the Note above ;
also note that a plus sign is not permitted);
the remaining '-'s are separators between
parts of the date portion;
the first mm is a two-digit
numeral that represents the month;
dd is a two-digit numeral
that represents the day;
'T' is a separator indicating that time-of-day follows;
hh is a two-digit numeral
that represents the hour; '24' is permitted if the
minutes and seconds represented are zero,
and the dateTime value so
represented is the first instant of the following day (the hour property of a
dateTime object in the
cannot have
a value greater than 23);
':' is a separator between parts of the time-of-day portion;
the second mm is a
two-digit numeral that represents the minute;
ss is a two-integer-digit numeral that represents the
whole seconds;
'.' s+ (if present) represents the
fractional seconds;
zzzzzz (if present) represents
the timezone (as described below).
For example, 2002-10-10T12:00:00-05:00 (noon on 10 October 2002, Central Daylight
Savings Time as well as Eastern Standard Time
in the U.S.) is 2002-10-10T17:00:00Z,
five hours later than 2002-10-10T12:00:00Z.
For further guidance on arithmetic with dateTimes and durations,
see .
Canonical representation
Except for trailing fractional zero digits in the seconds representation,
'24:00:00' time representations,
and timezone (for timezoned values), the mapping
from literals to values is one-to-one. Where there is more than
one possible representation, the canonical representation is as follows:
The 2-digit numeral representing
the hour must not be '24';
The fractional second string, if present,
must not end in '0';
for timezoned values, the timezone must be represented with
'Z' (All timezoned dateTime values are
.).
Lexical Mappings
The lexical representations for are as follows:
Lexical Space
dateTimeLexicalRep
- - T (( : : ) |
) ?
Day-of-month Representations
Within a , a &mustnot;
begin with the digit 3 or be 29
unless the value to
which it would map would satisfy the value constraint on
values
(Constraint: Day-of-month Values
) given above.
Leap-second Representations
Within a , a &mustnot;
begin with the digit 6 unless the value to
which it would map, in conjunction with the rest of the values,
would satisfy the value constraint on leap-second values
(Constraint: Leap-second Values
) given
above. Should a negative leap-second be declared, the
is further limited to those which would
satisfy the even-tighter value constraint on .
In such representations:
-
is a numeral consisting
of at least four decimal digits, optionally preceded by a minus sign;
leading 0 digits are prohibited except to bring the
digit count up to four.
It represents the value.
-
Subsequent -, T, and
:, separate the various numerals.
-
, , ,
and are numerals consisting
of exactly two decimal digits.
They represents
the , ,
, and values
respectively.
-
is a numeral consisting
of exactly two decimal digits, or two decimal digits,
a decimal point, and one or more trailing digits.
It represents the value.
-
Alternatively, combines the ,
, , and their separators to
represent midnight of the day, which is the first moment of the next
day.
-
, if present, specifies the timezone in which
the moment occurs. Timezones are a count of minutes (expressed in
as a count of hours and minutes) that are added
or subtracted from UTC time to get the local time.
Z is an alternative representation of the timzone of
UTC, which is, of course, zero minutes from UTC.
For example, 2002-10-10T12:00:00−05:00
(noon on 10 October 2002, Central Daylight
Savings Time as well as Eastern Standard Time
in the U.S.) is equal to 2002-10-10T17:00:00Z,
five hours later than 2002-10-10T12:00:00Z.
The production
is equivalent to this regular expression
once whitespace is removed, except
that the constraints above are not enforced.
\-?([1-9][0-9][0-9][0-9]+)|(0[0-9][0-9][0-9])\-(0[1-9])|(1[0-2])\-(0[1-9])([12][0-9])|(3[01])
T(([01][0-9])|(2[0-3]):[0-5][0-9]:(([0-65][0-9])|(60))(\.[0-9]+)?)|(24:00:00(\.[0-9]0+)?)
([+\-](0[0-9])|(1[0-4]):[0-5][0-9])?
Note that neither the production
production
nor this regular
expression alone enforce the constraints
on given above.
The lexical mapping and canonical mapping
for are the following functions:
The lexical mapping
for is .
The canonical mapping is .
Timezones
Timezones are durations with (integer-valued) hour and minute properties
(with the hour magnitude limited to at most 14, and the minute magnitude
limited to at most 59, except that if the hour magnitude is 14, the minute
value must be 0); they may be both positive or both negative.
The lexical representation of a timezone is a string of the form:
(('+' | '-') hh ':' mm) | 'Z',
where
hh is a two-digit numeral
(with leading zeros as required) that
represents the hours,
mm is a two-digit
numeral that represents the minutes,
'+' indicates a nonnegative duration,
'-' indicates a nonpositive duration.
The mapping so defined is one-to-one, except that '+00:00',
'-00:00', and 'Z' all represent the same zero-length duration
timezone, ; 'Z' is its canonical
representation.
When a timezone is added to a
dateTime, the result is the date
and time "in that timezone". For example, 2002-10-10T12:00:00+05:00 is
2002-10-10T07:00:00Z and 2002-10-10T00:00:00+05:00 is 2002-10-09T19:00:00Z.
Order relation on dateTime
dateTime value objects on either
timeline are totally ordered by their timeOnTimeline
values; between the two timelines, dateTime
value objects are ordered by their
timeOnTimeline values when their timeOnTimeline values differ by more than
fourteen hours, with those whose difference is a duration of 14 hours or less
being incomparable.
In general, the
order
relation on dateTime
is a partial order since there is no determinate relationship between certain
instants. For example, there is no determinate ordering between
(a) 2000-01-20T12:00:00 and (b) 2000-01-20T12:00:00Z. Based on
timezones currently in use, (c) could vary from 2000-01-20T12:00:00+12:00 to
2000-01-20T12:00:00-13:00. It is, however, possible for this range to expand or
contract in the future, based on local laws. Because of this, the following
definition uses a somewhat broader range of indeterminate values:
+14:00..-14:00.
The following definition uses the notation S[year] to represent the year
field of S, S[month] to represent the month field, and so on. The notation (Q
& "-14:00") means adding the timezone -14:00 to Q, where Q did not
already have a timezone. This is a
logical explanation of the process. Actual
implementations are free to optimize as
long as they produce the same results.
The ordering between two dateTimes P
and Q is defined by the following algorithm:
A.Normalize P and Q. That is, if there is a timezone present, but
it is not Z, convert it to Z using the addition operation defined in
Thus 2000-03-04T23:00:00+03:00
normalizes to 2000-03-04T20:00:00Z
B. If P and Q either both have a time zone or both do not have a time
zone, compare P and Q field by field from the year field down to the
second field, and return a result as soon
as it can be determined. That is:
For each i in {year, month, day, hour, minute, second}
If P[i] and Q[i] are both
not specified, continue to the next i
If P[i] is not specified
and Q[i] is, or vice versa, stop and return
P <> Q
If P[i] < Q[i], stop and return P < Q
If P[i] > Q[i], stop and return P > Q
Stop and return P = Q
C.Otherwise, if P contains a time zone and Q does not, compare
as follows:
P < Q if P < (Q with time zone +14:00)
P > Q if P > (Q with time zone -14:00)
P <> Q otherwise, that is, if (Q with time zone
+14:00) < P < (Q with time zone -14:00)
D. Otherwise, if P does not contain a time zone and Q does, compare
as follows:
P < Q if (P with time zone -14:00) < Q.
P > Q if (P with time zone +14:00) > Q.
P <> Q otherwise, that is, if (P with
time zone +14:00) < Q < (P with time zone -14:00)
Examples:
| Determinate |
Indeterminate |
| 2000-01-15T00:00:00
< 2000-02-15T00:00:00 |
2000-01-01T12:00:00 <>
1999-12-31T23:00:00Z |
| 2000-01-15T12:00:00
< 2000-01-16T12:00:00Z |
2000-01-16T12:00:00 <>
2000-01-16T12:00:00Z |
| |
2000-01-16T00:00:00
<> 2000-01-16T12:00:00Z |
Totally ordered dateTimes
Certain derived types from dateTime
can be guaranteed have a total order. To
do so, they must require that a specific
set of fields are always specified, and
that remaining fields (if any) are always unspecified. For example, the date
datatype without time zone is defined to contain exactly year, month, and day.
Thus dates without time zone have a total order among themselves.
Constraining facets
Facets
time
time
represents an instant of time that recurs every day. The
of time is the space
of time of day values as defined in § 5.3 of
. Specifically, it is a set of zero-duration daily
time instances.
represents instants of time that recur at the same point in each
calendar day, or that occur in some arbitrary calendar day.
Since the lexical representation allows an optional time zone
indicator, time values are partially ordered because it may
not be able to determine the order of two values one of which has a
time zone and the other does not. The order relation on
time values is the
using an arbitrary date. See also
. Pairs
of time values with or without time
zone indicators are totally ordered.
See the conformance note in
which applies to the seconds part
of this datatype as well.
Value Space
uses the , with
, ,
and required
to be absent. remains
.
Leap-second Values
The value
&must; be
less than 60 if
is absent or if the remaining
values do not correspond to a time
at which, on some day, a leap-second has been introduced
into by the responsible
authorities;
if
the hour and minute in the specified timezone
allow a real leap-second then the value
&must; be less than 60 plus the largest number of
leap-seconds introduced on any date. (At
the time of publication of this specification, the
largest number of leap-seconds ever introduced at one time
is 1, so the largest legal
value is 60. Historically, all leap-seconds have been introduced
in the last minute of December and June in no
more than one leap-second has ever been introduced at
a time and it appears unlikely that this will ever occur. No negative leap-seconds have been
introduced, but if any should be introduced in future,
adding that negative number will result
in a value limit of 59 or lower.)
See the conformance note in
which applies to the value of this datatype.
RQ-13 (time
zone crosses date line)
The "seven property model" rewrite of
date/time datatype descriptions includes
a carefully crafted definition of order
that insures that for repeating datatypes (time, gDay, etc.), timezoned values
will be compared as though they are on the same calendar day
(local property values) so that in any given timezone,
the days start at local
00:00:00 and end immediately before local 24:00:00.
Days in timezones other than Z do not run from 00:00:00Z to 24:00:00Z.
Equality and order are as prescribed in
. values
(points in time in an arbitrary day) are ordered
taking into account their .
A calendar ( or local time) day with an early
timezone begins earlier than the same calendar day with a later
timezone. Since the timezones allowed spread over 28 hours,
there are timezone pairs for which a given calendar day in the two
timezones are totally disjoint—the earlier day ends before the
same day starts in the later timezone. The moments in time
represented by a single calendar day are spread over a 52-hour
interval, from the beginning of the day in the +14:00 timezone to the
end of that day in the −14:00 timezone.
Since the order of a value
having a
with another value whose
is absent is determined
by imputing timezones of both +14:00 and −14:00
to the untimezoned value, many such combinations will be
because the two imputed
timezones yield different orders. However,
for a given untimezoned value, there will
always be timezoned values at one or both
ends of the 52-hour interval that are
comparable
(because the interval of
incomparability
is only 24 hours wide).
Examples that show the difference from version 1.0 of this specification (see
for the notations):
-
A day is a calendar (or local
time) day in each timezone.
08:00:00+10:00 < 17:00:00+10:00
(just as 08:00:00Z has always been less than
17:00:00Z, but in version 1.0
08:00:00+10:00 > 17:00:00+10:00 )
-
A value in a calendar day with an early timezone
may precede every value in a later calendar day:
00:00:00+01:00 is less than every value with
Z
-
A calendar day with a very early timezone may be completely
disjoint from a calendar day with a very late timezone:
Each value with
+13:00 is less than every
value with −13:00
-
values do not always
convert to
in the same way as in 1.0, since a time
in a timezone may convert to
a time on
a different day (whereas time
conversions in version 1.0 wrapped around
by ignoring the day during conversion):
22:00:00Z > 03:00:00+05:00
(since 1971-12-31T03:00:00+05 is 1979-12-30T22:00:00Z,
not 1979-12-31T22:00:00Z); in the previous
version of this specification 22:00:00Z =
03:00:00+05:00 )
Lexical representation
The lexical representation for time is the left
truncated lexical representation for :
hh:mm:ss.sss with optional
following time zone indicator. For example,
to indicate 1:20 pm for Eastern
Standard Time which is 5 hours behind
Coordinated Universal Time (),
one would write: 13:20:00-05:00. See also
.
Canonical representation
The canonical representation for time is defined
by prohibiting certain options from the
.
Specifically, either the time zone must
be omitted or, if present, the time zone must be Coordinated Universal
Time () indicated by a "Z".
Additionally, the canonical representation for midnight is 00:00:00.
Lexical Mappings
The lexical representations for
are projections of
those of , as follows:
Lexical Space
timeLexicalRep
(( : : ) |
) ?
Leap-second Representations
An &mustnot; begin with the
digit 6 unless the value to
which it would map would satisfy the value
constraint on leap-second values given above.
The production
is equivalent to this
regular expression, once whitespace is
removed, except
that the regular expression does not
enforce the constraint just given):
(([01][0-9])|(2[0-3]):[0-5][0-9]:[0-6][0-9])|(24:00:00)
(([01][0-9])|(2[0-3]):[0-5][0-9]:(([0-65][0-9])|(60))(.[0-9]+)?)|(24:00:00(.[0-9]+)?)
([+\-](0[0-9])|(1[0-4]):[0-5][0-9])?
(((([01][0-9])|(2[0-3])):([0-5][0-9]):(([0-5][0-9])(\.[0-9]+)?))
|(24:00:00(\.0+)?))
(Z|((+|-)(0[0-9]|1[0-4]):[0-5][0-9]))?
Note that neither
the production
nor this regular
expression alone enforce the constraint
on given above.
The lexical mapping and canonical mapping
for are the following functions:
The lexical mapping
for is
; the canonical mapping is
.
Constraining facets
Facets
date
The
of date
consists of top-open intervals of
exactly one day in length on the timelines of
, beginning on the beginning moment of each day (in
each timezone), i.e. '00:00:00', up
to but not including '24:00:00' (which is
identical with
'00:00:00'date
represents top-open intervals of exactly one day in length on the timelines of
, beginning on the beginning moment of each day (in
each timezone), up to but not including the beginning
moment of the next day). For nontimezoned values, the top-open
intervals disjointly cover the nontimezoned timeline,
one per day. For timezoned
values, the intervals begin at every minute and therefore overlap.
A "date object" is an object with year,
month, and day properties just like those
of objects, plus
an optional timezone-valued
timezone property. (As with values of timezones are a
special case of durations.)
Just as a object corresponds to a point on one of the
timelines, a date object corresponds to an interval on one
of the two timelines as just described.
Timezoned date values track the starting moment of their day, as
determined by their timezone; said timezone is generally recoverable for
canonical representations.
The recoverable timezone is that duration which
is the result of subtracting the first moment (or any moment) of the timezoned
date from the first moment (or the
corresponding moment) on the
same date. s are
always durations between '+12:00' and
'-11:59'. This "timezone normalization"
(which follows automatically from the definition of the date
) is explained more in
.
For example: the first moment of 2002-10-10+13:00 is 2002-10-10T00:00:00+13,
which is 2002-10-09T11:00:00Z, which is also the first moment of 2002-10-09-11:00.
Therefore 2002-10-10+13:00 is 2002-10-09-11:00;
they are the same interval.
For most timezones, either the first moment or last moment of the day (a
value, always
) will have a date portion
different from that of the date itself!
However, noon of that date (the midpoint of the interval) in that
(normalized) timezone will always have the same date portion as the
date itself, even when that noon point in time is normalized to
. For example,
2002-10-10-05:00 begins during 2002-10-09Z and 2002-10-10+05:00
ends during 2002-10-11Z, but noon of both 2002-10-10-05:00 and 2002-10-10+05:00
falls in the interval which is 2002-10-10Z.
See the conformance note in which
applies to the year part of this datatype as well.
Value Space
uses the , with
, ,
and required
to be absent. remains
.
Day-of-month Values
The value &must; be
no more than 30 if
is one of 4, 6, 9, or 11, no more than 28
if is 2 and
is not divisble 4,
or is divisible by 100 but not by 400,
and no more than 29 if
is 2 and
is divisible by 400, or by 4 but not by 100.
See the conformance note in
which applies to the year
part
value of this datatype
as well.
Equality and order are as prescribed in
.
In version 1.0 of this specification, values
did not retain a timezone explicitly, but for timezones not too far from
their timezone could be recovered based on
their value's first moment on the timeline. The
retains all timezones.
Examples that show the difference from version 1.0 (see
for the notations):
-
A day is a calendar (or local
time) day in each timezone,
including the timezones outside of +12:00 through -11:59 inclusive:
2000-12-12+13:00 < 2000-12-12+11:00
(just as 2000-12-12+12:00 has always been less than
2000-12-12+11:00, but in version 1.0
2000-12-12+13:00 > 2000-12-12+11:00 ,
since 2000-12-12+13:00's recoverable
timezone was −11:00)
-
Similarly:
2000-12-12+13:00 = 2000-12-13−11:00
(whereas under 1.0, as just
stated, 2000-12-12+13:00 = 2000-12-12−11:00)
Lexical representation
For the following discussion, let the
"date portion" of a
or date object be an object
similar to a or
date object, with similar year, month, and day properties, but no
others, having the same value for these properties as the original
or date object.
The of
date consists of finite-length
sequences of characters of the form:
'-'? yyyy '-' mm '-' dd zzzzzz?
where the date and optional timezone are represented exactly the
same way as they are for . The first moment of the
interval is that represented by:
'-' yyyy '-' mm '-' dd 'T00:00:00' zzzzzz?
and the least upper bound of the interval is the timeline point represented
(noncanonically) by:
'-' yyyy '-' mm '-' dd 'T24:00:00' zzzzzz?.
The of a date will always be
a duration between '+12:00' and
'11:59'. Timezone lexical representations, as
explained for , can range from '+14:00' to '-14:00'.
The result is that literals of dates with very large or very
negative timezones will map to a "normalized" date value with a
different from that represented in the original
representation, and a matching difference
of +/- 1 day in the date itself.
Canonical representation
Given a member of the date , the
date portion of the canonical
representation (the entire representation
for nontimezoned values, and all but the
timezone representation for timezoned values)
is always the date portion
of the canonical
representation of the interval midpoint
(the representation,
truncated on the right to eliminate 'T' and all following characters).
For timezoned values, append the canonical
representation of the .
Lexical Mappings
The lexical representations for
are projections of
those of , as follows:
Lexical Space
dateLexicalRep
- - ?
Day-of-month Representations
Within a
,
a &mustnot;
begin with the digit 3 or be 29
unless the value to
which it would map would satisfy the value constraint on
values
(Constraint: Day-of-month Values
) given above.
The production
is equivalent to this
regular expression,
except that it does not enforce
the constraint just noted:
\-?([1-9][0-9][0-9][0-9]+)|(0[0-9][0-9][0-9])\-(0[1-9])|(1[0-2])\-([0-2][0-9])|(3[01])((+|\-)(0[0-9]|1[0-4]):[0-5][0-9])?
Note that neither
the production
nor this regular
expression alone enforce the constraint
on given above.
The lexical mapping and canonical mapping
for are the following functions:
The lexical mapping
for is .
The canonical mapping is .
gYearMonth
gYearMonth represents a specific gregorian month in a specific
gregorian year. The of
gYearMonth is the set of Gregorian calendar months as defined
in § 5.2.1 of . Specifically, it is a set
of one-month long, non-periodic instances e.g. 1999-10 to represent the whole
month of 1999-10, independent of how many days this month has.
gYearMonth
represents specific whole Gregorian months in specific
Gregorian years.
Since the lexical representation allows an optional
time zone indicator, gYearMonth values are partially ordered
because it may not be possible to unequivocally determine the order of two
values one of which has a time zone and the other does not. If
gYearMonth values are considered as periods of time, the order
relation on gYearMonth values is the order relation on their
starting instants. This is discussed in .
See also . Pairs of
gYearMonth values with or without time zone indicators are
totally ordered.
Because month/year combinations in one calendar only rarely correspond
to month/year combinations in other calendars, values of this type
are not, in general, convertible to simple values corresponding to month/year
combinations in other calendars. This type should therefore be used
with caution in contexts where conversion to other calendars is desired.
See the conformance note in
which applies to the year part of this datatype as well.
Value Space
uses the , with
, ,
, and required
to be absent. remains
.
See the conformance note in
which applies to the value of this datatype.
Equality and order are as prescribed in
.
In version 1.0 of this specification,
values did not
retain a timezone explicitly, but timezones not too far from
could be recovered based on the
value's first moment on the timeline. The
simply retains all timezones.
An example that shows the difference from version 1.0 (see
for the notations):
-
A day is a calendar (or local time) day in
each timezone, including the timezones outside of +12:00 through
−11:59 inclusive:
2000-12+13:00 < 2000-12+11:00
(just as 2000-12+12:00 has always been less than 2000−12+11:00,
but in version 1.0 2000-12+13:00 >
2000-12+11:00 , since 2000−12+13:00's recoverable
timezone was −11:00)
Lexical
representationMappings
The lexical representation for gYearMonth is the reduced
(right truncated) lexical representation for :
CCYY-MM. No left truncation is allowed. An optional following time
zone qualifier is allowed. To accommodate year values outside the
range from 0001 to 9999, additional digits
can be added to the left of this representation and a
preceding "-" sign is allowed.
For example, to indicate the month of May 1999, one would write: 1999-05.
See also .
The lexical representations for
are projections of
those of , as follows:
Lexical Space
gYearMonthLexicalRep
- ?
The is equivalent to this regular expression:
\-?([1-9][0-9][0-9][0-9]+)|(0[0-9][0-9][0-9])\-(0[1-9])|(1[0-2])((+|\-)(0[0-9]|1[0-4]):[0-5][0-9])?
The
lexical mapping and canonical mapping
for are the following functions:
The lexical mapping
for is .
The canonical mapping is .
Constraining facets
Facets
gYear
gYear represents a
gregorian calendar year. The of
gYear is the set of Gregorian calendar years as defined in
§ 5.2.1 of . Specifically, it is a set of one-year
long, non-periodic instances
e.g. lexical 1999 to represent the whole year 1999, independent of
how many months and days this year has.
gYear
represents Gregorian calendar years.
Since the lexical representation allows an optional time zone
indicator, gYear values are partially ordered because it may
not be possible to unequivocally determine
the order of two values one of which has a
time zone and the other does not. If
gYear values are considered as periods of time, the order relation
on gYear values is the order relation on their starting instants.
This is discussed in . See also
. Pairs of
gYear values with or without time
zone indicators are totally ordered.
Because years in one calendar only rarely correspond to years
in other calendars, values of this type
are not, in general, convertible to simple values corresponding to years
in other calendars. This type should therefore be used with caution
in contexts where conversion to other calendars is desired.
See the conformance note in which
applies to the year part of this datatype
as well.
Value Space
uses the , with
, , ,
, and required
to be absent. remains
.
See the conformance note in
which applies to the value of this datatype.
Equality and order are as prescribed in
.
In version 1.0 of this specification,
values did not
retain a timezone explicitly, but timezones not too far from
could be recovered based on the
value's first moment on the timeline. The
simply retains all timezones.
An example that shows the difference from version 1.0 (see
for the notations):
-
A day is a calendar (or local time) day in
each timezone, including the timezones outside of +12:00 through
−11:59 inclusive:
2000+13:00 < 2000+11:00
(just as 2000+12:00 has always been less than 2000+11:00,
but in version 1.0 2000+13:00 >
2000+11:00 , since 2000+13:00's recoverable
timezone was −11:00)
Lexical
representationMappings
The lexical representation for gYear is the reduced (right
truncated) lexical representation for : CCYY.
No left truncation is allowed. An optional following time
zone qualifier is allowed as for . To
accommodate year values outside the range from 0001 to 9999, additional
digits can be added to the left of this representation and a preceding
"-" sign is allowed.
For example, to indicate 1999, one would write: 1999.
See also .
The lexical representations for
are projections of
those of , as follows:
Lexical Space
gYearLexicalRep
- ?
The is equivalent to this regular expression:
\-?([1-9][0-9][0-9][0-9]+)|(0[0-9][0-9][0-9])((+|\-)(0[0-9]|1[0-4]):[0-5][0-9])?
The lexical mapping
and canonical mapping
for are the following functions:
The lexical mapping
for is .
The canonical mapping
is .
Constraining facets
Facets
gMonthDay
gMonthDay is a gregorian date that recurs, specifically a day of
the year such as the third of May. Arbitrary recurring dates are not
supported by this datatype. The of
gMonthDay is the set of calendar
dates, as defined in § 3 of . Specifically,
it is a set of one-day long, annually periodic instances.
represents whole calendar
days that recur at the same point in each calendar year, or that occur
in some arbitrary calendar year.
This datatype can be used, for example, to record
birthdays; an instance of the datatype could be used to say that
someone's birthday occurs on the 14th of September every year.
Since the lexical representation allows an optional time zone
indicator, gMonthDay values are partially ordered because it may
not be possible to unequivocally determine the order of two values one of which has a
time zone and the other does not. If
gMonthDay values are considered as periods of time,
in an arbitrary leap year, the order relation
on gMonthDay values is the order relation on their starting instants.
This is discussed in . See also
. Pairs of gMonthDay values with or without time zone indicators are totally ordered.
Because day/month combinations in one calendar only rarely correspond
to day/month combinations in other calendars, values of this type do not,
in general, have any straightforward or intuitive representation
in terms of most other calendars. This type should therefore be
used with caution in contexts where conversion to other calendars
is desired.
Value Space
uses the , with
, , , and required
to be absent. remains
.
Day-of-month Values
The value &must; be no more than 30 if
is one of 4, 6, 9, or 11, and no more than 29 if is 2.
Equality and order are as prescribed in
.
In version 1.0 of this specification, values
did not retain a timezone explicitly, but for timezones not too far from
their timezone could be recovered based on
their value's first moment on the timeline. The
retains all timezones.
An example that shows the difference from version 1.0 (see
for the notations):
-
A day is a calendar (or local time) day in each timezone,
including the timezones outside of +12:00 through −11:59 inclusive:
--12-12+13:00 < --12-12+11:00
(just as --12-12+12:00 has always been less than
--12-12+11:00, but in version 1.0
--12-12+13:00 > --12-12+11:00 , since
--12-12+13:00's recoverable
timezone was −11:00)
Lexical
representationMappings
The lexical representation for gMonthDay is the left
truncated lexical representation for : --MM-DD.
An optional following time
zone qualifier is allowed as for .
No preceding sign is allowed. No other formats are
allowed. See also .
The lexical representations for
are projections
of those of , as follows:
Lexical Space
gMonthDayLexicalRep
-- - ?
Day-of-month Representations
Within a , a &mustnot;
begin with the digit 3 or be 29
unless the value to
which it would map would satisfy the value constraint on
values
(Constraint: Day-of-month Values
) given above.
The is equivalent to this regular
expression(note that it does
not enforce the constraint just mentioned):
\-\-(0[1-9])|(1[0-2])\-([0-2][0-9])|(3[01])((+|\-)(0[0-9]|1[0-4]):[0-5][0-9])?
Note that neither
the production
nor this regular
expression alone enforce the constraint
on given above.
This datatype can be used to represent a
specific day in a month. To say, for example, that my birthday occurs
on the 14th of September ever year.
The
lexical mapping and canonical mapping
for are the following functions:
The lexical mapping
for is .
The canonical mapping is .
Constraining facets
Facets
gDay
gDay is a gregorian day that recurs, specifically a day
of the month such as the 5th of the month. Arbitrary recurring days
are not supported by this datatype. The
of gDay is the space of a set of calendar
dates as defined in § 3 of . Specifically,
it is a set of one-day long, monthly periodic instances.
gDay
is a datatype that represents
whole days within an arbitrary month—days that recur at the same
point in each (Gregorian) month. This datatype can
beis used to represent a specific day of the month.
To say, for example, that I get my paycheckindicate, for example, that an employee gets a paycheck on the 15th of each month. (Obviously, days
beyond 28 cannot occur in all months; they are nonetheless permitted, up to 31.)
Since the lexical representation allows an optional time zone
indicator, gDay values are partially ordered because it may
not be possible to unequivocally determine the order of two values one of
which has a time zone and the other does not. If
gDay values are considered as periods of time,
in an arbitrary month that has 31 days,
the order relation
on gDay values is the order relation on their starting instants.
This is discussed in . See also
. Pairs of gDay
values with or without time zone indicators are totally ordered.
Because days in one calendar only rarely
correspond to days in other calendars,
gday values
of this type do not, in general, have any straightforward or
intuitive representation in terms of most
othernon-Gregorian
calendars.
This
typegday
should therefore be used with caution in contexts where conversion to
other calendars is desired.
Value Space
uses the , with
, ,
, ,
and required to be
absent. remains
and
must be between 1 and 31 inclusive.
Equality and order are as prescribed in
. Since
values (days) are ordered by their first moments, it is possible
for apparent anomalies to appear in the order when
values
are differ by at least 24
hours. (It is possible for
values to differ by up to 28 hours.)
Examples that may appear anomalous (see for the notations):
---15 < ---16 , but ---15−13:00 > ---16+13:00
---15−11:00 = ---16+13:00
---15−13:00 <> ---16 ,
because ---15−13:00 > ---16+14:00
and ---15−13:00 < 16−14:00
Timezones do not cause wrap-around at the end of the month:
---31−13:00 in one month
may start after ---01+13:00 in the next
month,the last day of a
given month in timezone −13:00 may start after the first
day of the next month in timezone +13:00, as
measured on the global timeline,
but nonetheless
---01+13:00 < ---31−13:00 .
Lexical
representationMappings
The lexical representation for gDay is the left
truncated lexical representation for : ---DD .
An optional following time
zone qualifier is allowed as for . No preceding sign is
allowed. No other formats are allowed. See also .
Lexical Mappings
The lexical representations for are
restrictionsprojections
of those of , as follows:
Lexical Space
gDayLexicalRep
--- ?
The is equivalent to this regular expression:
---\-\-\-([0-2][0-9]|3[01])((+|\-)(0[0-9]|1[0-4]):[0-5][0-9])?
The lexical mapping and canonical mapping for are defined as follows:
The lexical mapping
for is .
The canonical mapping is .
&CFacet;s
Facets
gMonth
gMonth is a gregorian month that recurs every year.
The
of gMonth is the space of a set of calendar
months as defined in § 3 of . Specifically,
it is a set of one-month long, yearly periodic instances.
This datatype can be used to represent a
specific month. To say, for example, that Thanksgiving falls in the month of
November.gDaygMonth
represents whole (Gregorian) months
within an arbitrary year—months that recur at the same point in
each year. It might be used, for example, to say what
month annual Thanksgiving celebrations fall in different countries
(--11 in the United States, --10 in Canada, and possibly other months in
other countries).
Since the lexical representation allows an optional time zone
indicator, gMonth values are partially ordered because it may
not be possible to unequivocally determine the order of two values one of which has a
time zone and the other does not. If
gMonth values are considered as periods of time, the order relation
on gMonth is the order relation on their starting instants.
This is discussed in . See also
. Pairs of gMonth
values with or without time zone indicators are totally ordered.
Because months in one calendar only rarely correspond
to months in other calendars, values of this type do not,
in general, have any straightforward or intuitive representation
in terms of most other calendars. This type should therefore be
used with caution in contexts where conversion to other calendars
is desired.
Value Space
uses the , with
, , , , and required
to be absent. remains
.
Equality and order are as prescribed in
.
In version 1.0 of this specification, values
did not retain a timezone explicitly, but for timezones not too far from
their timezone could be recovered based on
their value's first moment on the timeline. The
retains all timezones.
An example that shows the difference from version 1.0 (see
for the notations):
-
A month is a calendar (or local time) month in each timezone,
including the timezones outside of +12:00 through −11:59 inclusive:
--12+13:00 < --12+11:00
(just as --12+12:00 has always been less than --12+11:00, but in version 1.0
--12+13:00 > --12+11:00 , since --12+13:00's recoverable
timezone was −11:00)
Lexical
representationMappings
The lexical representation for gMonth is the left
and right truncated lexical representation for : --MM.
An optional following time
zone qualifier is allowed as for . No preceding sign is
allowed. No other formats are allowed. See also .
The lexical representations for are projections of
those of , as follows:
Lexical Space
gMonthLexicalRep
-- ?
The is equivalent to this regular expression:
\-\-(0[1-9])|(1[0-2])((+|\-)(0[0-9]|1[0-4]):[0-5][0-9])?
The
lexical mapping and canonical mapping
for are defined as follows:
The lexical mapping for is .
The canonical mapping is .
Constraining facets
Facets
hexBinary
hexBinary represents
arbitrary hex-encoded binary data. The of
hexBinary is the set of finite-length sequences of binary
octets.
Lexical Representation
hexBinary has a lexical representation where
each binary octet is encoded as a character tuple, consisting of two
hexadecimal digits ([0-9a-fA-F]) representing the octet code. For example,
"0FB7" is a hex encoding for the 16-bit integer 4023
(whose binary representation is 111110110111).
Canonical Representation
The canonical representation for hexBinary is defined
by prohibiting certain options from the
. Specifically, the lower case
hexadecimal digits ([a-f]) are not allowed.
Constraining facets
Facets
base64Binary
base64Binary
represents Base64-encoded arbitrary binary data. The of
base64Binary is the set of finite-length sequences of binary
octets. For base64Binary data the
entire binary stream is encoded using the Base64
Alphabet in
Encoding
defined in , which is derived from the
encoding described in .
The lexical forms of base64Binary values are limited to the 65 characters
of the Base64 Alphabet defined in
,
i.e., a-z,
A-Z, 0-9, the plus sign (+), the forward slash (/) and the
equal sign (=), together with the characters defined in as white space.
No other characters are allowed.
For compatibility with older mail gateways, suggests that
base64 data should have lines limited to at most 76 characters in length. This
line-length limitation is not required by
and is not
mandated in the lexical forms of base64Binary
data and . It
must not&mustnot;
be enforced by XML Schema processors.
The lexical space of base64Binary is given by the following grammar
(the notation is that used in ); legal lexical forms must match
the Base64Binary production.
Base64Binary ::= ((B64S B64S B64S B64S)*
((B64S B64S B64S B64) |
(B64S B64S B16S '=') |
(B64S B04S '=' #x20? '=')))?
B64S ::= B64 #x20?
B16S ::= B16 #x20?
B04S ::= B04 #x20?
B04 ::= [AQgw]
B16 ::= [AEIMQUYcgkosw048]
B64 ::= [A-Za-z0-9+/]
Note that this grammar requires the number of non-whitespace characters in the lexical
form to be a multiple of four, and for equals signs to appear only at the end of the
lexical form; strings which do not meet these constraints are not legal lexical forms
of base64Binary because they cannot successfully be decoded by base64
decoders.
The above definition of the lexical space is more restrictive than that
given in as regards whitespace —
and less restrictive than .
thisThis
is not an issue in practice. Any string compatible with theeither RFC can occur in
an element or attribute validated by this type, because the
facet of this type is fixed
to collapse, which means that all leading and trailing whitespace
will be stripped, and all internal whitespace collapsed to single space
characters, before the above grammar is enforced.
The possibility of ignoring whitespace
in base64 data is foreseen in clause 2.3 of , but
for the reasons given there this specification does not allow implementations
to ignore non-whitespace characters which are not in the Base64 Alphabet.
The canonical lexical form of a base64Binary data value is the base64
encoding of the value which matches the Canonical-base64Binary production in the following
grammar:
Canonical-base64Binary ::= (B64
B64 B64 B64)*
((B64 B64 B16 '=') | (B64 B04 '=='))?
For some values the canonical form defined above does not conform to
, which requires
breaking with linefeeds at appropriate intervals.
It does conform with
.
The length of a base64Binary value is the number of octets it contains.
This may be calculated from the lexical form by removing whitespace and padding characters
and performing the calculation shown in the pseudo-code below:
lex2 := killwhitespace(lexform) -- remove whitespace characters
lex3 := strip_equals(lex2) -- strip padding characters at end
length := floor (length(lex3) * 3 / 4) -- calculate length
Note on encoding: and
explicitly
references US-ASCII encoding. However,
decoding of base64Binary data in an XML entity is to be performed on the
Unicode characters obtained after character encoding processing as specified by
Constraining facets
Facets
anyURI
anyURI represents a
Uniform Resource Identifier Reference
(URI)an
Internationalized Resource Identifier Reference
(IRI). An anyURI value can be absolute or relative, and may
have an optional fragment identifier (i.e., it may be
a URIan
IRI Reference). This type should be used
to specify the intention
thatwhen
the value fulfills the role of
a URI as defined by , as amended by
an IRI,
as defined in or its successor(s) in the IETF
Standards Track.
IRIs may be used to locate resources
or simply to identify them. In the case where they are used to locate
resources using a URI, applications should use
theThe mapping from anyURI
values to URIs
is as definedgiven
by the URI reference escaping procedure defined in
Section 5.4
Locator Attribute
of (see also Section
87
Character Encoding in URI
References of )Section
3.1 Mapping
of IRIs to URIs of
or its successor(s) in the IETF Standards Track.
This means that a wide range of internationalized resource identifiers
can be specified when an anyURI is called for, and still
be understood as URIs per
, as amended by ,
where appropriate to identify
resources
and its successor(s).
Section 5.4 Locator Attribute
of requires that relative URI references be absolutized
as defined in before use. This is an XLink-specific
requirement and is not appropriate for XML Schema, since neither the
nor the
of the type are restricted to absolute URIs. Accordingly
absolutization must not be performed by schema processors as part of schema
validation.
Each URI scheme imposes specialized syntax rules for URIs in
that scheme, including restrictions on the syntax of allowed
fragment
identifiers. Because it is
impractical for processors to check that a value is a
context-appropriate URI reference, this specification follows the
lead of (as amended by )
in this matter: such rules and restrictions are not part of type validity
and are not checked by processors.
Thus in practice the above definition imposes only very modest obligations
on processors.
Lexical representationmapping
The of anyURI is
finite-length
character sequences which,
when the algorithm defined in Section 5.4 of is
applied to them, result in strings which are legal URIs according to
, as amended by .
For an value to be
usable in practice as an IRI, the result of applying to it
the algorithm defined in Section 3.1 of
should
be a string which is a legal URI according
to . (This is true at the time this document is published;
if in the future
and are replaced by other specifications
in the IETF Standards Track, the relevant constraints will be those
imposed by those successor specifications.)
Each URI scheme imposes specialized syntax rules
for URIs in that scheme, including restrictions on the syntax of
allowed fragment identifiers. Because it is impractical for processors
to check that a value is a context-appropriate URI reference,
neither the syntactic constraints defined by the definitions of individual
schemes nor the generic syntactic constraints defined by
and and their
successors are part of this datatype as defined here.
Applications which depend on values
being legal according to the rules of
the relevant specifications
should make arrangements to check values against the appropriate
definitions of IRI, URI, and specific schemes.
Spaces are, in principle, allowed in the
of anyURI, however, their use is highly discouraged
(unless they are encoded by %20).
The lexical mapping for is
the identity mapping.
The definitions of URI in the current
IETF specifications define certain URIs as equivalent to each other.
Those equivalences are not part of this datatype as defined here:
if two equivalent URIs or IRIs are different character
sequences, they map to different values in this datatype.
Constraining facets
Facets
QName
QName represents
XML qualified
names.
The of QName is the set of
tuples {namespace name,
local part},
where namespace name
is an
and local part is
an .
The of QName is the set
of strings that the
QName production of as defined
in .
The mapping between &literals; in the and
values in the of QName requires
a namespace declaration to be in scope for the context in which QName
is used.
Because the lexical representations available for
any value of type vary with context, no canonical
representation is defined for QName in this specification.
Value Space
Properties of
Values
namespaceName
an value
localPart
a NCName
(from )
Prefix Context
The is limited to those
values whose corresponding URI
can be associated with an appropriate
Prefix
(from ).
The content of the is
thus context dependent. An implementation is obligated to
deal with this dependency, especially in the implementation
of the .
Lexical Mapping
The of is the set
of &strings; that the
QName
production of , provided they are in a context
where the
Prefix of the
QName
is properly associated with a namespace URL.
The lexical mapping
for is the following function:
The lexical mapping
for is .
Because the
lexical representations
available for any value of type vary with context, no
is defined for
in this specification.
Simple Type Definition for QName
The of is present in every
schema. It has the following properties:
of
QName
http://www.w3.org/2001/XMLSchema
The
The empty set
atomic
{a facet with
= collapse and
= true}
{
an facet
with = false
a facet
with = false
a facet
with = countable
a facet
with = true
global
absent
absent
The empty sequence
Constraining facets
Facets
The use of , and
on or
datatypes from is
deprecated. Future versions of this specification may
remove these facets for this datatype.
NOTATION
NOTATION
represents the NOTATION
attribute
type from .
The
of NOTATION is the set of s
of notations declared in the current schema.
The of NOTATION is the set
of all names of notations
declared in the current schema (in the form of
s).
enumeration facet value required for NOTATION
It is an for NOTATION
to be used directly in a schema. Only datatypes that are
from NOTATION by
specifying a value for can be used
in a schema.
For compatibility (see )
NOTATIONFor
compatibility
should be used only on attributes
and should only be used in schemas with no
target namespace.
Because the lexical representations available for any given value
of vary with context, this specification defines
no canonical representation for values.
Value Space
Properties of
Values
namespaceName
an value
localPart
a NCName
(from )
NOTATION Prefix Context
The is limited to those
values whose corresponding URI
can be associated with an appropriate
Prefix
(from ).
NOTATION Schema Context
The and
must match the corresponding properties of some
notation declaration component
in the schema.
The content of the is
thus context dependent. An implementation is obligated to
deal with this dependency, especially in the implementation
of the .
Lexical Mapping
The of is the set
of &strings; that the
NOTATION
production of , provided they are in a context
where the
Prefix of the
NOTATION
is properly associated with a namespace URL.
The lexical mapping
for is the following function:
The lexical mapping
for is .
Because the
lexical representations
available for any value of type vary with context, no
is defined for
in this specification.
Simple Type Definition for NOTATION
The of is present in every
schema. It has the following properties:
of
NOTATION
http://www.w3.org/2001/XMLSchema
The
The empty set
atomic
{a facet with
= collapse and
= true}
{
an facet
with = false
a facet
with = false
a facet
with = countable
a facet
with = true
global
absent
absent
The empty sequence
Constraining facets
Facets
The use of , and
on or
datatypes from is
deprecated. Future versions of this specification may
remove these facets for this datatype.
Derived datatypesOther Built-in Datatypes
This section gives conceptual definitions for all
&ordinary.d.onp;
datatypes defined by this specification. The XML representation used to define
datatypes (whether
or &user-defined.x;) is
given in section
and the complete
definitions of the &ordinary.d.onp;
datatypes are provided in Appendix Athe appendix .
normalizedString
normalizedString
represents white space normalized strings.
The of normalizedString is the
set of strings that do not
contain the carriage return (#xD), line feed (#xA) nor tab (#x9) characters.
The of normalizedString is the
set of strings that do not
contain the carriage return (#xD),
line feed (#xA)
nor tab (#x9) characters.
The of normalizedString is .
Constraining facets
Facets
Derived datatypes
token
token
represents tokenized strings.
The of token is the
set of strings that do not
contain the
carriage return (#xD),
line feed (#xA) nor tab (#x9) characters, that have no
leading or trailing spaces (#x20) and that have no internal sequences
of two or more spaces.
The of token is the
set of strings that do not contain the
carriage return (#xD),
line feed (#xA) nor tab (#x9) characters, that have no
leading or trailing spaces (#x20) and that have no internal sequences
of two or more spaces.
The of token is .
Constraining facets
Facets
Derived datatypes
language
language
represents formal
natural language identifiers,
as defined
by or its
successor(s) in the IETF Standards Track.
The
of language is the set of all strings that are
valid language identifiers as defined
. The
and of
language
isare
the set of all strings that conform to the pattern
[a-zA-Z]{1,8}(-[a-zA-Z0-9]{1,8})*
,
This is the set of strings accepted by the grammar given in
.
The of language is .
The regular expression above provides the only normative
constraint on the lexical and value spaces of this type. The
additional constraints imposed on language identifiers by
and its successor(s), and in particular their requirement that language
codes be registered with IANA or ISO if not given in ISO 639, are
not part of this datatype as defined here.
specifies that
language codes are to be treated as case insensitive; there
exist conventions for capitalization of some of them, but these should
not be taken to carry meaning. For instance, [ISO 3166] recommends
that country codes are capitalized (MN Mongolia), while [ISO 639]
recommends that language codes are written in lower case (mn
Mongolian).
Since the datatype is
derived from , it inherits from
a one-to-one mapping from lexical
representations to values. The literals MN and
mn therefore correspond to distinct values and
have distinct canonical forms. Users of this specification should be
aware of this fact, the consequence of which is that the
case-insensitive treatment of language values prescribed by
does not follow from the definition of
this datatype given here; applications which require
case-sensitivity should make appropriate adjustments.
Constraining facets
Facets
NMTOKEN
NMTOKEN represents
the NMTOKEN attribute type
from . The of
NMTOKEN is the set of tokens that
the Nmtoken production in
. The of
NMTOKEN is the set of strings that
the Nmtoken production in
. The of
NMTOKEN is .
For compatibility (see ) NMTOKEN
should be used only on attributes.
Constraining facets
Facets
DerivedRelated datatypes
NMTOKENS
NMTOKENS
represents the NMTOKENS attribute
type from . The
of NMTOKENS is the set of finite, non-zero-length sequences of
s. The
of NMTOKENS is the set of space-separated lists of tokens,
of which each token is in the of
. The of
NMTOKENS is .
For compatibility (see )
NMTOKENS should be used only on attributes.
Constraining facets
Facets
Name
Name
represents XML Names.
The of Name is
the set of all strings which the
Name production of
. The of
Name is the set of all strings which
the Name production of
. The of Name
is .
Constraining facets
Facets
Derived datatypes
NCName
NCName represents XML
"non-colonized" Names. The of
NCName is the set of all strings which
the NCName production of
. The of
NCName is the set of all strings which
the NCName production of
. The of
NCName is .
Constraining facets
Facets
Derived datatypes
ID
ID represents the
ID attribute type from
. The of
ID is the set of all strings that
the NCName production in
. The
of ID is the set of all
strings that the
NCName production in
.
The of ID is .
For compatibility (see )
ID should be used only on attributes.
Uniqueness of items validated as is not
part of this datatype as defined here.
When this specification is used in conjunction with
, uniqueness is enforced at a
different level, not as part of datatype validity;
see Validation Rule: Validation Root Valid (ID/IDREF)
in .
Constraining facets
Facets
IDREF
IDREF represents the
IDREF attribute type from
. The of
IDREF is the set of all strings that
the NCName production in
. The
of IDREF is the set of
strings that the
NCName production in
.
The of IDREF is .
For compatibility (see ) this datatype
should be used only on attributes.
Existence of referents for items validated as
is not part of this
datatype as defined here.
When this specification is used in conjunction with
, referential integrity is enforced at a
different level, not as part of datatype validity;
see Validation Rule: Validation
Root Valid (ID/IDREF) in .
Constraining facets
Facets
DerivedRelated datatypes
IDREFS
IDREFS represents the
IDREFS attribute type from
. The of
IDREFS is the set of finite, non-zero-length sequences of
s.
The of IDREFS is the
set of space-separated lists of tokens, of which each token is in the
of .
The of IDREFS is
.
For compatibility (see ) IDREFS
should be used only on attributes.
Existence of referents for items validated as
is not
part of this datatype as defined here.
When this specification is used in conjunction with
, referential integrity is enforced at a
different level, not as part of datatype validity;
see Validation Rule:
Validation Root Valid (ID/IDREF) in .
Constraining facets
Facets
ENTITY
ENTITY represents the
ENTITY attribute type from
. The of
ENTITY is the set of all strings that
the NCName production in
and have been declared as an
unparsed entity in
a document type definition.
The of ENTITY is the set
of all strings that the
NCName production in
.
The of ENTITY is .
The of ENTITY is scoped
to a specific instance document.
For compatibility (see ) ENTITY
should be used only on attributes.
Constraining facets
Facets
DerivedRelated datatypes
ENTITIES
ENTITIES
represents the ENTITIES attribute
type from . The
of ENTITIES is the set of finite, non-zero-length sequences of
s that have been declared as
unparsed entities
in a document type definition.
The of ENTITIES is the
set of space-separated lists of tokens, of which each token is in the
of .
The of ENTITIES is
.
The of ENTITIES is scoped
to a specific instance document.
For compatibility (see ) ENTITIES
should be used only on attributes.
Constraining facets
Facets
integer
integer is
from by fixing the
value of to be 0 and
disallowing the trailing decimal point.
This results in the standard
mathematical concept of the integer numbers. The
of integer is the infinite
set {...,-2,-1,0,1,2,...}. The of
integer is .
Lexical representation
integer has a lexical representation consisting of a finite-length sequence
of decimal digits (#x30-#x39) with an optional leading sign. If the sign is omitted,
"+" is assumed. For example: -1, 0, 12678967543233, +100000.
Canonical representation
The canonical representation for integer is defined
by prohibiting certain options from the
. Specifically, the preceding optional "+" sign is prohibited and leading zeroes are prohibited.
Constraining facets
Facets
Derived datatypes
nonPositiveInteger
nonPositiveInteger is from
by setting the value of
to be 0. This results in the
standard mathematical concept of the non-positive integers.
The of nonPositiveInteger
is the infinite set {...,-2,-1,0}. The
of nonPositiveInteger is .
Lexical representation
nonPositiveInteger has a lexical representation consisting of
an optional preceding sign
followed by a finite-length sequence of decimal digits (#x30-#x39).
The sign may be "+" or may be omitted only for
lexical forms denoting zero; in all other lexical forms, the negative
sign ("-") must be present.
For example: -1, 0, -12678967543233, -100000.
Canonical representation
The canonical representation for nonPositiveInteger is defined
by prohibiting certain options from the
.
In the canonical form for zero, the sign must be
omitted. Leading zeroes are prohibited.
Constraining facets
Facets
Derived datatypes
negativeInteger
negativeInteger is from
by setting the value of
to be -1. This results in the
standard mathematical concept of the negative integers. The
of negativeInteger
is the infinite set {...,-2,-1}. The
of negativeInteger is .
Lexical representation
negativeInteger has a lexical representation consisting of
a negative sign ("-") followed by a finite-length
sequence of decimal digits (#x30-#x39). For example: -1, -12678967543233, -100000.
Canonical representation
The canonical representation for negativeInteger is defined
by prohibiting certain options from the
. Specifically, leading zeroes are prohibited.
Constraining facets
Facets
long
long is
from by setting the
value of to be 9223372036854775807
and to be -9223372036854775808.
The of long is
.
Lexical representation
long has a lexical representation consisting
of an optional sign followed by a finite-length
sequence of decimal digits (#x30-#x39). If the sign is omitted, "+" is assumed.
For example: -1, 0,
12678967543233, +100000.
Canonical representation
The canonical representation for long is defined
by prohibiting certain options from the
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
Constraining facets
Facets
Derived datatypes
int
int
is from by setting the
value of to be 2147483647 and
to be -2147483648. The
of int is .
Lexical representation
int has a lexical representation consisting
of an optional sign followed by a finite-length
sequence of decimal digits (#x30-#x39). If the sign is omitted, "+" is assumed.
For example: -1, 0,
126789675, +100000.
Canonical representation
The canonical representation for int is defined
by prohibiting certain options from the
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
Constraining facets
Facets
Derived datatypes
short
short is
from by setting the
value of to be 32767 and
to be -32768. The
of short is
.
Lexical representation
short has a lexical representation consisting
of an optional sign followed by a finite-length sequence of decimal
digits (#x30-#x39). If the sign is omitted, "+" is assumed.
For example: -1, 0, 12678, +10000.
Canonical representation
The canonical representation for short is defined
by prohibiting certain options from the
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
Constraining facets
Facets
Derived datatypes
byte
byte
is from
by setting the value of to be 127
and to be -128.
The of byte is
.
Lexical representation
byte has a lexical representation consisting
of an optional sign followed by a finite-length
sequence of decimal digits (#x30-#x39). If the sign is omitted, "+" is assumed.
For example: -1, 0,
126, +100.
Canonical representation
The canonical representation for byte is defined
by prohibiting certain options from the
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
Constraining facets
Facets
nonNegativeInteger
nonNegativeInteger is from
by setting the value of
to be 0. This results in the
standard mathematical concept of the non-negative integers. The
of nonNegativeInteger
is the infinite set {0,1,2,...}. The of
nonNegativeInteger is .
Lexical representation
nonNegativeInteger has a lexical representation consisting of
an optional sign followed by a finite-length
sequence of decimal digits (#x30-#x39). If the sign is omitted,
the positive sign ("+") is assumed.
If the sign is present, it must be "+" except for lexical forms
denoting zero, which may be preceded by a positive ("+") or a negative ("-") sign.
For example:
1, 0, 12678967543233, +100000.
Canonical representation
The canonical representation for nonNegativeInteger is defined
by prohibiting certain options from the
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
Constraining facets
Facets
Derived datatypes
unsignedLong
unsignedLong is from
by setting the value of
to be 18446744073709551615.
The of unsignedLong is
.
Lexical representation
unsignedLong has a lexical representation consisting
of a finite-length sequence of decimal digits (#x30-#x39).
For example: 0,
12678967543233, 100000.
Canonical representation
The canonical representation for unsignedLong is defined
by prohibiting certain options from the
. Specifically,
leading zeroes are prohibited.
Constraining facets
Facets
Derived datatypes
unsignedInt
unsignedInt is from
by setting the value of
to be 4294967295. The
of unsignedInt is
.
Lexical representation
unsignedInt has a lexical representation consisting
of a finite-length
sequence of decimal digits (#x30-#x39). For example: 0,
1267896754, 100000.
Canonical representation
The canonical representation for unsignedInt is defined
by prohibiting certain options from the
. Specifically,
leading zeroes are prohibited.
Constraining facets
Facets
Derived datatypes
unsignedShort
unsignedShort is from
by setting the value of
to be 65535. The
of unsignedShort is
.
Lexical representation
unsignedShort has a lexical representation consisting
of a finite-length
sequence of decimal digits (#x30-#x39).
For example: 0,
12678, 10000.
Canonical representation
The canonical representation for unsignedShort is defined
by prohibiting certain options from the
. Specifically, the
leading zeroes are prohibited.
Constraining facets
Facets
Derived datatypes
unsignedByte
unsignedByte is from
by setting the value of
to be 255. The
of unsignedByte is
.
Lexical representation
unsignedByte has a lexical representation consisting
of a finite-length
sequence of decimal digits (#x30-#x39).
For example: 0,
126, 100.
Canonical representation
The canonical representation for unsignedByte is defined
by prohibiting certain options from the
. Specifically,
leading zeroes are prohibited.
Constraining facets
Facets
positiveInteger
positiveInteger is from
by setting the value of
to be 1. This results in the standard
mathematical concept of the positive integer numbers.
The of positiveInteger
is the infinite set {1,2,...}. The of
positiveInteger is .
Lexical representation
positiveInteger has a lexical representation consisting
of an optional positive sign ("+") followed by a finite-length
sequence of decimal digits (#x30-#x39).
For example: 1, 12678967543233, +100000.
Canonical representation
The canonical representation for positiveInteger is defined
by prohibiting certain options from the
. Specifically, the
optional "+" sign is prohibited and leading zeroes are prohibited.
Constraining facets
Facets
yearMonthDuration
yearMonthDuration is a datatype from
by restricting its lexical
representations to instances of
. The of
yearMonthDuration
is therefore that of restricted to those whose
property is 0. This results in a duration datatype which is totally ordered.
The always-zero is formally retained in order that
's (abstract) value space truly be a subset of that of
An obvious implementation optimization is to ignore the zero and implement
values simply as values.
The Lexical Mapping
The lexical space is reduced from that of by
disallowing and
fragments in the lexical representations.
The
, called
herein, is that of restricted to the lexical space.
The Lexical
Representation
yearMonthDurationLexicalRep
-? P
The regular expression
-?P([0-9]+Y)?([0-9]+M)? has instances that
are not in the lexical space—but they are not in the
lexical space of either, so it
serves as a relatively simple regular expression
that extracts from the
of those representations that are
instances of .
The lexical
space of consists of
strings which match the regular expression
-?P((([0-9]+Y)([0-9]+M)?)|([0-9]+M)) or the
expression -?P[0-9]+(Y([0-9]+M)?|M), but the
formal definition of uses a
simpler regular expression in its &pattern.tc;
facet: [^DT]*. This pattern matches only
strings of characters which contain no D
and no T, thus restricting the &lexical_space;
of to strings with no day, hour,
minute, or seconds fields.
Canonical mappings are not used during schema processing.
They are provided in this specification for the benefit of other users
of these datatype definitions
datatypes who may find them useful, and for other
specifications which might find it useful to reference them
normatively.
The is that of restricted in its
range to the (which reduces its domain to omit any
values not in the value space).
The value whose and
are both zero has no in this datatype since its
in (PT0S)
is not in the
of .
&CFacet;s
Facets
dayTimeDuration
dayTimeDuration is a datatype from
by restricting its lexical
representations to instances of
. The of
dayTimeDuration
is therefore that of restricted to those whose
property is 0. This results in a duration datatype which is totally ordered.
The Lexical Space
The lexical space is reduced from that of by
disallowing and
fragments in the lexical representations.
The
, called
herein, is that of restricted to
the lexical space.
The Lexical Representation
dayTimeDurationLexicalRep
-? P
The regular expression
-?P([0-9]+D)?(T([0-9]+H)?([0-9]+M)?([0-9]+(.[0-9]+)?S)?)?
has several instances that are not in the lexical space—but they
are not in the lexical space of either, so it
serves as a relatively simple regular expression that extracts from
the of those
representations that are instances of .
The lexical space of
consists of
strings in the &lexical_space; of which
match the regular expression [^YM]*[DT].*;
this pattern eliminates all durations with year or month fields,
leaving only those with day, hour, minutes, and/or seconds
fields.
Canonical mappings are not used during schema processing.
They are provided in this specification for the benefit of other users
of these datatype definitions
datatypes who may find them useful, and for other
specifications which might find it useful to reference them
normatively.
The is that of restricted
in its
range to the (which reduces its domain to omit any
values not into the value
space).
&CFacet;s
Facets