XML Schema Part 2: Datatypes Second Edition
XML Schema Part 2: Datatypes Second Edition
W3C Recommendation 28 October 2004
This version:
Latest version:
Previous version:
Editors:
Paul V. Biron, Kaiser Permanente, for Health Level Seven
Ashok Malhotra, Microsoft (formerly of IBM)
Please refer to the
errata
for this document, which may include some normative corrections.
This document is also available in these non-normative formats:
XML
XHTML with visible change markup
Independent copy of the schema for schema documents
A schema for built-in datatypes only, in a separate namespace
, and
Independent copy of the DTD for schema documents
See also
translations
W3C
MIT
ERCIM
Keio
), All Rights Reserved. W3C
liability
trademark
and
document use
rules apply.
Abstract
XML Schema: Datatypes
is part 2 of the specification of the XML
Schema language. It defines facilities for defining datatypes to be used
in XML Schemas as well as other XML specifications.
The datatype language, which is itself represented in
XML 1.0, provides a superset of the capabilities found in XML 1.0
document type definitions (DTDs) for specifying datatypes on elements
and attributes.
Status of this Document
This section describes the status of this document at the
time of its publication. Other documents may supersede this document.
A list of current W3C publications and the latest
revision of this technical report can be found in the
W3C technical reports index
at
This is a
W3C
Recommendation
, which forms part of the Second Edition of XML
Schema. This document has been reviewed by W3C Members and
other interested parties and has been endorsed by the Director as a
W3C Recommendation. It is a stable document and may be used as
reference material or cited as a normative reference
from another document.
W3C's role in making the Recommendation is to draw attention
to the specification and to promote its widespread deployment. This
enhances the functionality and interoperability of the Web.
This document has been produced by the
W3C XML Schema Working Group
as part of the W3C
XML
Activity
. The goals of the XML Schema language are discussed in
the
XML Schema
Requirements
document. The authors of this document are the
members of the XML Schema Working Group. Different parts of this
specification have different editors.
This document was produced under the
24
January 2002 Current Patent Practice (CPP)
as amended by the
W3C Patent Policy
Transition Procedure
. The Working Group maintains a
public
list of patent disclosures
relevant to this document;
that page also includes instructions for disclosing a patent.
An individual who
has actual knowledge of a patent which the individual believes
contains Essential Claim(s) with respect to this specification should
disclose the information in accordance with
section
6 of the W3C Patent Policy
The English version of this specification is the only normative
version. Information about translations of this document is available
at
This second edition is
not
a new version,
it merely incorporates the changes dictated by the corrections to
errors found in the
first
edition
as agreed by the XML Schema Working Group, as a
convenience to readers. A separate list of all such corrections is
available at
The errata list for this second edition is available at
Please report errors in this document to
www-xml-schema-comments@w3.org
archive
).
Note:
Ashok Malhotra's
affiliation has changed since the completion of
editorial work on this second edition. He is now at Oracle, and can be
contacted at
Table of Contents
Introduction
1.1
Purpose
1.2
Requirements
1.3
Scope
1.4
Terminology
1.5
Constraints and Contributions
Type System
2.1
Datatype
2.2
Value space
2.3
Lexical space
2.4
Facets
2.5
Datatype dichotomies
Built-in datatypes
3.1
Namespace considerations
3.2
Primitive datatypes
3.3
Derived datatypes
Datatype components
4.1
Simple Type Definition
4.2
Fundamental Facets
4.3
Constraining Facets
Conformance
Appendices
Schema for Datatype Definitions (normative)
DTD for Datatype Definitions (non-normative)
Datatypes and Facets
C.1
Fundamental Facets
ISO 8601 Date and Time Formats
D.1
ISO 8601 Conventions
D.2
Truncated and Reduced Formats
D.3
Deviations from ISO 8601 Formats
Adding durations to dateTimes
E.1
Algorithm
E.2
Commutativity and Associativity
Regular Expressions
F.1
Character Classes
Glossary (non-normative)
References
H.1
Normative
H.2
Non-normative
Acknowledgements (non-normative)
1 Introduction
1.1 Purpose
The
[XML 1.0 (Second Edition)]
specification defines limited
facilities for applying datatypes to document content in that documents
may contain or refer to DTDs that assign types to elements and attributes.
However, document authors, including authors of traditional
documents
and those transporting
data
in XML,
often require a higher degree of type checking to ensure robustness in
document understanding and data interchange.
The table below offers two typical examples of XML instances
in which datatypes are implicit: the instance on the left
represents a billing invoice, the instance on the
right a memo or perhaps an email message in XML.
Data oriented
Document oriented
We need to discuss the latest
draft
Either email me at
mailto:paul.v.biron@kp.org
or call
The invoice contains several dates and telephone numbers, the postal
abbreviation for a state
(which comes from an enumerated list of sanctioned values), and a ZIP code
(which takes a definable regular form). The memo contains many
of the same types of information: a date, telephone number, email address
and an "importance" value (from an enumerated
list, such as "low", "medium" or "high"). Applications which process
invoices and memos need to raise exceptions if something that was
supposed to be a date or telephone number does not conform to the rules
for valid dates or telephone numbers.
In both cases, validity constraints exist on the content of the
instances that are not expressible in XML DTDs. The limited datatyping
facilities in XML have prevented validating XML processors from supplying
the rigorous type checking required in these situations. The result
has been that individual applications writers have had to implement type
checking in an ad hoc manner. This specification addresses
the need of both document authors and applications writers for a robust,
extensible datatype system for XML which could be incorporated into
XML processors. As discussed below, these datatypes could be used in other
XML-related standards as well.
1.2 Requirements
The
[XML Schema Requirements]
document spells out
concrete requirements to be fulfilled by this specification,
which state that the XML Schema Language must:
provide for primitive data typing, including byte, date,
integer, sequence, SQL and Java primitive datatypes, etc.;
define a type system that is adequate for import/export
from database systems (e.g., relational, object, OLAP);
distinguish requirements relating to lexical data representation
vs. those governing an underlying information set;
allow creation of user-defined datatypes, such as
datatypes that are derived from existing datatypes and which
may constrain certain of its properties (e.g., range,
precision, length, format).
1.3 Scope
This portion of the XML Schema Language discusses datatypes that can be
used in an XML Schema. These datatypes can be specified for element
content that would be specified as
#PCDATA
and attribute
values of
various
types
in a DTD. It is the intention of this specification
that it be usable outside of the context of XML Schemas for a wide range
of other XML-related activities such as
[XSL]
and
[RDF Schema]
1.4 Terminology
The terminology used to describe XML Schema Datatypes is defined in the
body of this specification. The terms defined in the following list are
used in building those definitions and in describing the actions of a
datatype processor:
[Definition:]
for compatibility
A feature of this specification included solely to ensure that schemas
which use this feature remain compatible with
[XML 1.0 (Second Edition)]
[Definition:]
may
Conforming documents and processors are permitted to but need
not behave as described.
[Definition:]
match
(Of strings or names:) Two strings or names being compared must be
identical. Characters with multiple possible representations in ISO/IEC 10646 (e.g.
characters with both precomposed and base+diacritic forms) match only if they have
the same representation in both strings. No case folding is performed. (Of strings and
rules in the grammar:) A string matches a grammatical production if it belongs to the
language generated by that production.
[Definition:]
must
Conforming documents and processors are required to behave as
described; otherwise they are in
error
[Definition:]
error
A violation of the rules of this specification; results are undefined.
Conforming software
may
detect and report an
error
and
may
recover from it.
1.5 Constraints and Contributions
This specification provides three different kinds of normative
statements about schema components, their representations in XML and
their contribution to the schema-validation of information items:
[Definition:]
Constraint on Schemas
Constraints on the schema components themselves, i.e. conditions
components
must
satisfy to be components at all.
Largely to be found in
Datatype components (§4)
[Definition:]
Schema Representation Constraint
Constraints on the representation of schema components in XML. Some but
not all of these are expressed in
Schema for Datatype Definitions (normative) (§A)
and
DTD for Datatype Definitions (non-normative) (§B)
[Definition:]
Validation Rule
Constraints expressed by schema components which information
items
must
satisfy to be schema-valid. Largely
to be found in
Datatype components (§4)
2 Type System
This section describes the conceptual framework behind the type system
defined in this specification. The framework has been influenced by the
[ISO 11404]
standard on language-independent datatypes as
well as the datatypes for
[SQL]
and for programming
languages such as Java.
The datatypes discussed in this specification are computer
representations of well known abstract concepts such as
integer
and
date
. It is not the place of this
specification to define these abstract concepts; many other publications
provide excellent definitions.
2.1 Datatype
[Definition:]
In this specification,
datatype
is a 3-tuple, consisting of
a) a set of distinct values, called its
value space
b) a set of lexical representations, called its
lexical space
, and c) a set of
facet
that characterize properties of the
value space
individual values or lexical items.
2.2 Value space
[Definition:]
value
space
is the set of values for a given datatype.
Each value in the
value space
of a datatype is denoted by
one or more literals in its
lexical space
The
value space
of a given datatype can
be defined in one of the following ways:
defined axiomatically from fundamental notions (intensional definition)
[see
primitive
enumerated outright (extensional definition)
[see
enumeration
defined by restricting the
value space
of
an already defined datatype to a particular subset with a given set
of properties [see
derived
defined as a combination of values from one or more already defined
value space
(s) by a specific construction procedure
[see
list
and
union
value space
s have certain properties. For example,
they always have the property of
cardinality
some definition of
equality
and might be
ordered
, by which individual
values within the
value space
can be compared to
one another. The properties of
value space
s that
are recognized by this specification are defined in
Fundamental facets (§2.4.1)
2.3 Lexical space
In addition to its
value space
, each datatype also
has a lexical space.
[Definition:]
lexical space
is the set of valid
literals
for a datatype.
For example, "100" and "1.0E2" are two different literals from the
lexical space
of
float
which both
denote the same value. The type system defined in this specification
provides a mechanism for schema designers to control the set of values
and the corresponding set of acceptable literals of those values for
a datatype.
Note:
The literals in the
lexical space
s defined in this specification
have the following characteristics:
Interoperability:
The number of literals for each value has been kept small; for many
datatypes there is a one-to-one mapping between literals and values.
This makes it easy to exchange the values between different systems.
In many cases, conversion from locale-dependent representations will
be required on both the originator and the recipient side, both for
computer processing and for interaction with humans.
Basic readability:
Textual, rather than binary, literals are used.
This makes hand editing, debugging, and similar activities possible.
Ease of parsing and serializing:
Where possible, literals correspond to those found in common
programming languages and libraries.
2.3.1 Canonical Lexical Representation
While the datatypes defined in this specification have, for the most part,
a single lexical representation i.e. each value in the datatype's
value space
is denoted by a single literal in its
lexical space
, this is not always the case. The
example in the previous section showed two literals for the datatype
float
which denote the same value. Similarly, there
may
be
several literals for one of the date or time datatypes that denote the
same value using different timezone indicators.
[Definition:]
canonical lexical representation
is a set of literals from among the valid set of literals
for a datatype such that there is a one-to-one mapping between literals
in the
canonical lexical representation
and
values in the
value space
2.4 Facets
2.4.1
Fundamental facets
2.4.2
Constraining or Non-fundamental facets
[Definition:]
facet
is a single
defining aspect of a
value space
. Generally
speaking, each facet characterizes a
value space
along independent axes or dimensions.
The facets of a datatype serve to distinguish those aspects of
one datatype which
differ
from other datatypes.
Rather than being defined solely in terms of a prose description
the datatypes in this specification are defined in terms of
the
synthesis
of facet values which together determine the
value space
and properties of the datatype.
Facets are of two types:
fundamental
facets that define
the datatype and
non-fundamental
or
constraining
facets that constrain the permitted values of a datatype.
2.4.1 Fundamental facets
[Definition:]
fundamental facet
is an abstract property which
serves to semantically characterize the values in a
value space
All
fundamental facets
are fully described in
Fundamental Facets (§4.2)
2.4.2 Constraining or Non-fundamental facets
[Definition:]
constraining facet
is an optional property that can be
applied to a datatype to constrain its
value space
Constraining the
value space
consequently constrains
the
lexical space
. Adding
constraining facet
s to a
base type
is described in
Derivation by restriction (§4.1.2.1)
All
constraining facets
are fully described in
Constraining Facets (§4.3)
2.5 Datatype dichotomies
2.5.1
Atomic vs. list vs. union datatypes
2.5.2
Primitive vs. derived datatypes
2.5.3
Built-in vs. user-derived datatypes
It is useful to categorize the datatypes defined in this specification
along various dimensions, forming a set of characterization dichotomies.
2.5.1 Atomic vs. list vs. union datatypes
The first distinction to be made is that between
atomic
list
and
union
datatypes.
[Definition:]
Atomic
datatypes
are those having values which are regarded by this specification as
being indivisible.
[Definition:]
List
datatypes are those having values each of which consists of a
finite-length (possibly empty) sequence of values of an
atomic
datatype.
[Definition:]
Union
datatypes are those whose
value space
s and
lexical space
s are the union of
the
value space
s and
lexical space
s of one or more other datatypes.
For example, a single token which
match
es
Nmtoken
from
[XML 1.0 (Second Edition)]
could be the value of an
atomic
datatype (
NMTOKEN
); while a sequence of such tokens
could be the value of a
list
datatype
NMTOKENS
).
2.5.1.1 Atomic datatypes
atomic
datatypes can be either
primitive
or
derived
. The
value space
of an
atomic
datatype
is a set of "atomic" values, which for the purposes of this specification,
are not further decomposable. The
lexical space
of
an
atomic
datatype is a set of
literals
whose internal structure is specific to the datatype in question.
2.5.1.2 List datatypes
Several type systems (such as the one described in
[ISO 11404]
) treat
list
datatypes as
special cases of the more general notions of aggregate or collection
datatypes.
list
datatypes are always
derived
The
value space
of a
list
datatype is a set of finite-length sequences of
atomic
values. The
lexical space
of a
list
datatype is a set of literals whose internal
structure is a space-separated
sequence of literals of the
atomic
datatype of the items in the
list
[Definition:]
The
atomic
or
union
datatype that participates in the definition of a
list
datatype
is known as the
itemType
of that
list
datatype.
Example
list
datatype can be
derived
from an
atomic
datatype whose
lexical space
allows space
(such as
string
or
anyURI
)or a
union
datatype any of whose
{member type definitions}
's
lexical space
allows space.
In such a case, regardless of the input, list items
will be separated at space boundaries.
Example
this is not list item 1
this is not list item 2
this is not list item 3
In the above example, the value of the
someElement
element
is not a
list
of
length
3;
rather, it is a
list
of
length
18.
When a datatype is
derived
from a
list
datatype, the following
constraining facet
s apply:
length
maxLength
minLength
enumeration
pattern
whiteSpace
For each of
length
maxLength
and
minLength
, the
unit of length
is
measured in number of list items. The value of
whiteSpace
is fixed to the value
collapse
For
list
datatypes the
lexical space
is composed of space-separated
literals of its
itemType
. Hence, any
pattern
specified when a new datatype is
derived
from a
list
datatype is matched against
each literal of the
list
datatype and
not against the literals of the datatype that serves as its
itemType
Example
The
canonical-lexical-representation
for the
list
datatype is defined as the lexical form in which
each item in the
list
has the canonical lexical
representation of its
itemType
2.5.1.3 Union datatypes
The
value space
and
lexical space
of a
union
datatype are the union of the
value space
s and
lexical space
s of
its
memberTypes
union
datatypes are always
derived
Currently, there are no
built-in
union
datatypes.
Example
A prototypical example of a
union
type is the
maxOccurs attribute
on the
element element
in XML Schema itself: it is a union of nonNegativeInteger
and an enumeration with the single member, the string "unbounded", as shown below.
Any number (greater than 1) of
atomic
or
list
datatype
s can participate in a
union
type.
[Definition:]
The datatypes that participate in the
definition of a
union
datatype are known as the
memberTypes
of that
union
datatype.
The order in which the
memberTypes
are specified in the
definition (that is, the order of the
element, or the order of the
QName
s in the
memberTypes
attribute) is significant.
During validation, an element or attribute's value is validated against the
memberTypes
in the order in which they appear in the
definition until a match is found. The evaluation order can be overridden
with the use of
xsi:type
Example
For example, given the definition below, the first instance of the
validates correctly as an
integer (§3.3.13)
, the second and third as
string (§3.2.1)
The
canonical-lexical-representation
for a
union
datatype is defined as the lexical form in which
the values have the canonical lexical representation
of the appropriate
memberTypes
Note:
A datatype which is
atomic
in this specification
need not be an "atomic" datatype in any programming language used to
implement this specification. Likewise, a datatype which is a
list
in this specification need not be a "list"
datatype in any programming language used to implement this specification.
Furthermore, a datatype which is a
union
in this
specification need not be a "union" datatype in any programming
language used to implement this specification.
2.5.2 Primitive vs. derived datatypes
Next, we distinguish between
primitive
and
derived
datatypes.
[Definition:]
Primitive
datatypes are those that are not defined in terms of other datatypes;
they exist
ab initio
[Definition:]
Derived
datatypes are those that are defined in terms of other datatypes.
For example, in this specification,
float
is a well-defined
mathematical
concept that cannot be defined in terms of other datatypes, while
integer
is a special case of the more general datatype
decimal
[Definition:]
The simple ur-type definition is a special restriction of the
ur-type definition
whose name is
anySimpleType
in the XML Schema namespace.
anySimpleType
can be
considered as the
base type
of all
primitive
datatypes.
anySimpleType
is considered to have an unconstrained lexical space and a
value space
consisting of the union of the
value space
s of all the
primitive
datatypes and the set of all lists of all members of the
value space
s of all the
primitive
datatypes.
The datatypes defined by this specification fall into both
the
primitive
and
derived
categories. It is felt that a judiciously chosen set of
primitive
datatypes will serve the widest
possible audience by providing a set of convenient datatypes that
can be used as is, as well as providing a rich enough base from
which the variety of datatypes needed by schema designers can be
derived
In the example above,
integer
is
derived
from
decimal
Note:
A datatype which is
primitive
in this specification
need not be a "primitive" datatype in any programming language used to
implement this specification. Likewise, a datatype which is
derived
in this specification need not be a
"derived" datatype in any programming language used to implement
this specification.
As described in more detail in
XML Representation of Simple Type Definition Schema Components (§4.1.2)
each
user-derived
datatype
must
be defined in terms of another datatype in one of three ways: 1) by assigning
constraining facet
s which serve to
restrict
the
value space
of the
user-derived
datatype to a subset of that of the
base type
; 2) by creating
list
datatype whose
value space
consists of finite-length sequences of values of its
itemType
; or 3) by creating a
union
datatype whose
value space
consists of the union of the
value space
s of its
memberTypes
2.5.2.1 Derived by restriction
[Definition:]
A datatype is said to be
derived
by
restriction
from another datatype
when values for zero or more
constraining facet
s are specified
that serve to constrain its
value space
and/or its
lexical space
to a subset of those of its
base type
[Definition:]
Every
datatype that is
derived
by
restriction
is defined in terms of an existing datatype, referred to as its
base type
base type
s can be either
primitive
or
derived
2.5.2.2 Derived by list
list
datatype can be
derived
from another datatype (its
itemType
) by creating
value space
that consists of a finite-length sequence
of values of its
itemType
2.5.2.3 Derived by union
One datatype can be
derived
from one or more
datatypes by
union
ing their
value space
and, consequently, their
lexical space
s.
2.5.3 Built-in vs. user-derived datatypes
[Definition:]
Built-in
datatypes are those which are defined in this specification,
and can be either
primitive
or
derived
[Definition:]
User-derived
datatypes are those
derived
datatypes that are defined by individual schema designers.
Conceptually there is no difference between the
built-in
derived
datatypes
included in this specification and the
user-derived
datatypes which will be created by individual schema designers.
The
built-in
derived
datatypes
are those which are believed to be so common that if they were not
defined in this specification many schema designers would end up
"reinventing" them. Furthermore, including these
derived
datatypes in this specification serves to
demonstrate the mechanics and utility of the datatype generation
facilities of this specification.
Note:
A datatype which is
built-in
in this specification
need not be a "built-in" datatype in any programming language used
to implement this specification. Likewise, a datatype which is
user-derived
in this specification need not
be a "user-derived" datatype in any programming language used to
implement this specification.
3 Built-in datatypes
Each built-in datatype in this specification (both
primitive
and
derived
) can be uniquely addressed via a
URI Reference constructed as follows:
the base URI is the URI of the XML Schema namespace
the fragment identifier is the name of the datatype
For example, to address the
int
datatype, the URI is:
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 maxInclusive facet, the URI is:
Additionally, each facet usage in a built-in datatype definition
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 datatype, followed
by a period (".") followed by the name of the facet
For example, to address the usage of the maxInclusive facet in
the definition of int, the URI is:
3.1 Namespace considerations
The
built-in
datatypes defined by this specification
are designed to be used with the XML Schema definition language as well as other
XML specifications.
To facilitate usage within the XML Schema definition language, the
built-in
datatypes in this specification have the namespace name:
To facilitate usage in specifications other than the XML Schema definition language,
such as those that do not want to know anything about aspects of the
XML Schema definition language other than the datatypes, each
built-in
datatype is also defined in the namespace whose URI is:
This applies to both
built-in
primitive
and
built-in
derived
datatypes.
Each
user-derived
datatype is also associated with a
unique namespace. However,
user-derived
datatypes
do not come from the namespace defined by this specification; rather,
they come from the namespace of the schema in which they are defined
(see
XML Representation of
Schemas
in
[XML Schema Part 1: Structures]
).
3.2 Primitive datatypes
3.2.1
string
3.2.2
boolean
3.2.3
decimal
3.2.4
float
3.2.5
double
3.2.6
duration
3.2.7
dateTime
3.2.8
time
3.2.9
date
3.2.10
gYearMonth
3.2.11
gYear
3.2.12
gMonthDay
3.2.13
gDay
3.2.14
gMonth
3.2.15
hexBinary
3.2.16
base64Binary
3.2.17
anyURI
3.2.18
QName
3.2.19
NOTATION
The
primitive
datatypes defined by this specification
are described below. For each datatype, the
value space
and
lexical space
are defined,
constraining facet
s which apply
to the datatype are listed and any datatypes
derived
from this datatype are specified.
primitive
datatypes can only be added by revisions
to this specification.
3.2.1 string
[Definition:]
The
string
datatype
represents character strings in XML. The
value space
of
string
is the set of finite-length sequences of
character
s (as defined in
[XML 1.0 (Second Edition)]
) that
match
the
Char
production from
[XML 1.0 (Second Edition)]
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.
Note:
Many human languages have writing systems that require
child elements for control of aspects such as bidirectional formating or
ruby annotation (see
[Ruby]
and Section 8.2.4
Overriding the
bidirectional algorithm: the BDO element
of
[HTML 4.01]
).
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
[XML Schema Language: Part 0 Primer]
Note:
As noted in
ordered
, the fact that this specification does
not specify an
order-relation
for
string
does not preclude other applications from treating strings as being ordered.
3.2.1.1 Constraining facets
string
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.2.1.2 Derived datatypes
The following
built-in
datatypes are
derived
from
string
normalizedString
3.2.2 boolean
[Definition:]
boolean
has the
value space
required to support the mathematical
concept of binary-valued logic: {true, false}.
3.2.2.1 Lexical representation
An instance of a datatype that is defined as
boolean
can have the following legal literals {true, false, 1, 0}.
3.2.2.2 Canonical representation
The canonical representation for
boolean
is the set of
literals {true, false}.
3.2.2.3 Constraining facets
boolean
has the
following
constraining facets
pattern
whiteSpace
3.2.3 decimal
[Definition:]
decimal
represents a subset of the real numbers, which can be represented by decimal numerals.
The
value space
of
decimal
is the set of
numbers that can be obtained by multiplying an integer by a non-positive
power of ten, i.e., expressible as
i × 10^-n
where
and
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
order-relation
on
decimal
is the order relation on real numbers, restricted
to this subset.
Note:
All
minimally conforming
processors
must
support decimal numbers with a minimum of 18 decimal digits (i.e., with a
totalDigits
of 18). However,
minimally conforming
processors
may
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
must
be clearly documented.
3.2.3.1 Lexical representation
decimal
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
3.2.3.2 Canonical representation
The canonical representation for
decimal
is defined by
prohibiting certain options from the
Lexical representation (§3.2.3.1)
. 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.
3.2.3.3 Constraining facets
decimal
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.3.4 Derived datatypes
The following
built-in
datatypes are
derived
from
decimal
integer
3.2.4 float
[Definition:]
float
is patterned after the IEEE single-precision 32-bit floating point type
[IEEE 754-1985]
. The basic
value space
of
float
consists of the values
m × 2^e
, where
is an integer whose absolute value is less than
2^24
, and
is an integer
between -149 and 104, inclusive. In addition to the basic
value space
described above, the
value space
of
float
also contains the
following
three
special values
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.
Positive infinity is greater than all other non-NaN values.
NaN equals itself but is
incomparable
with (neither greater than nor less than)
any other value in the
value space
Note:
"Equality" in this Recommendation is defined to be "identity" (i.e., values that
are identical in the
value space
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;
[IEEE 754-1985]
-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
minInclusive
maxInclusive
minExclusive
, and
maxExclusive
) will be
excluded from the resulting restricted
value space
. 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
value space
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
value space
to add NaN back in requires union with the NaN-only space.
This datatype differs from that of
[IEEE 754-1985]
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
[IEEE 754-1985]
only in that for schema purposes NaN = NaN.
A literal in the
lexical space
representing a
decimal number
maps to the normalized value
in the
value space
of
float
that is
closest to
in the sense defined by
[Clinger, WD (1990)]
; if
is
exactly halfway between two such values then the even value is chosen.
3.2.4.1 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
must
be an
integer
. The mantissa must be a
decimal
number. The representations
for exponent and mantissa must follow the lexical rules for
integer
and
decimal
. 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
3.2.4.2 Canonical representation
The canonical representation for
float
is defined by
prohibiting certain options from the
Lexical representation (§3.2.4.1)
. 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.
3.2.4.3 Constraining facets
float
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.5 double
[Definition:]
The
double
datatype
is patterned after the
IEEE double-precision 64-bit floating point
type
[IEEE 754-1985]
. The basic
value space
of
double
consists of the values
m × 2^e
, where
is an integer whose absolute value is less than
2^53
, and
is an
integer between -1075 and 970, inclusive. In addition to the basic
value space
described above, the
value space
of
double
also contains
the following
three
special values
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.
Positive infinity is greater than all other non-NaN values.
NaN equals itself but is
incomparable
with (neither greater than nor less than)
any other value in the
value space
Note:
"Equality" in this Recommendation is defined to be "identity" (i.e., values that
are identical in the
value space
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;
[IEEE 754-1985]
-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
minInclusive
maxInclusive
minExclusive
, and
maxExclusive
) will be
excluded from the resulting restricted
value space
. 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
value space
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
value space
to add NaN back in requires union with the NaN-only space.
This datatype differs from that of
[IEEE 754-1985]
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
[IEEE 754-1985]
only in that for schema purposes NaN = NaN.
A literal in the
lexical space
representing a
decimal number
maps to the normalized value
in the
value space
of
double
that is
closest to
; if
is
exactly halfway between two such values then the even value is chosen.
This is the
best approximation
of
[Clinger, WD (1990)]
[Gay, DM (1990)]
), which is more
accurate than the mapping required by
[IEEE 754-1985]
3.2.5.1 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
must
be
an integer. The mantissa must be a decimal number. The representations
for exponent and mantissa must follow the lexical rules for
integer
and
decimal
. 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
3.2.5.2 Canonical representation
The canonical representation for
double
is defined by
prohibiting certain options from the
Lexical representation (§3.2.5.1)
. 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.
3.2.5.3 Constraining facets
double
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.6 duration
[Definition:]
duration
represents a duration of time.
The
value space
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
[ISO 8601]
respectively. These components are ordered
in their significance by their order of appearance i.e. as year, month, day,
hour, minute, and second.
Note:
All
minimally conforming
processors
must
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,
minimally conforming
processors
may
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
must
be clearly documented.
3.2.6.1 Lexical representation
The lexical representation for
duration
is the
[ISO 8601]
extended format P
DT
S, where
Y represents the number of years,
M the
number of months,
D the number of days, 'T' is the
date/time separator,
H the number of hours,
M the number of minutes and
S 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
[ISO 8601]
, 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
[ISO 8601]
An optional preceding minus sign ('-') is
allowed, to indicate a negative duration. If the sign is omitted a
positive duration is indicated. See also
ISO 8601 Date and Time Formats (§D)
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
may
be omitted. However, at least one number and its designator
must
be present.
The seconds part
may
have a decimal fraction.
The designator 'T' must
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.
3.2.6.2 Order relation on duration
In general, the
order-relation
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
order-relation
of two
duration
values
and
is
x < y iff s+x < s+y
for each qualified
dateTime
in the list below. These values for
cause the greatest deviations in the addition of
dateTimes and durations. Addition of durations to time instants is defined
in
Adding durations to dateTimes (§E)
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
Adding durations to dateTimes (§E)
, they are still totally ordered.
Relation
1Y
> P
364D
<> P
365D
<> P
366D
< P
367D
1M
> P
27D
<> P
28D
<> P
29D
<> P
30D
<> P
31D
< P
32D
5M
> P
149D
<> P
150D
<> P
151D
<> P
152D
<> P
153D
< P
154D
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
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
...
3.2.6.3 Facet Comparison for durations
In comparing
duration
values with
minInclusive
minExclusive
maxInclusive
and
maxExclusive
facet values
indeterminate comparisons should be considered as "false".
3.2.6.4 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
[SQL]
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.
3.2.6.5 Constraining facets
duration
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.7 dateTime
[Definition:]
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
value space
of
decimal
with integers given units of seconds.
The
value space
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
value space
which lead to the
same results (i.e., are isomorphic) are of course acceptable.
All timezoned times are Coordinated Universal Time (UTC, sometimes called
"Greenwich Mean Time"). Other timezones indicated in lexical representations
are converted to UTC 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).
Note:
The date and time datatypes described in this recommendation were inspired
by
[ISO 8601]
. '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.
[ISO 8601]
makes no mention of the year 0; in
[ISO 8601:1998 Draft Revision]
the form '0000' was disallowed and this recommendation disallows it as well.
However,
[ISO 8601:2000 Second Edition]
, 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.
Note:
See the conformance note in
(§3.2.6)
which
applies to this datatype as well.
3.2.7.1 Lexical representation
The
lexical space
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
(§3.2.7)
; 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
value space
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
dateTime
s and durations,
see
Adding durations to dateTimes (§E)
3.2.7.2 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 '
';
for timezoned values, the timezone must be
represented with '
(All timezoned
dateTime
values are UTC.).
3.2.7.3 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, UTC; 'Z' is its canonical
representation.
When a timezone is added to a UTC
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.
3.2.7.4 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) 2000-01-20T12:00:00
. 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
dateTime
s 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
Adding durations to dateTimes (§E)
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
3.2.7.5 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.
3.2.7.6 Constraining facets
dateTime
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.8 time
[Definition:]
time
represents an instant of time that recurs every day. The
value space
of
time
is the space
of
time of day
values as defined in § 5.3 of
[ISO 8601]
. Specifically, it is a set of zero-duration daily
time instances.
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
Order relation on dateTime (§3.2.7.4)
using an arbitrary date. See also
Adding durations to dateTimes (§E)
. Pairs of
time
values with or without time zone indicators are totally ordered.
Note:
See the conformance note in
(§3.2.6)
which
applies to the seconds part of this datatype as well.
3.2.8.1 Lexical representation
The lexical representation for
time
is the left
truncated lexical representation for
dateTime
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 (UTC), one would write: 13:20:00-05:00. See also
ISO 8601 Date and Time Formats (§D)
3.2.8.2 Canonical representation
The canonical representation for
time
is defined
by prohibiting certain options from the
Lexical representation (§3.2.8.1)
. Specifically, either the time zone must
be omitted or, if present, the time zone must be Coordinated Universal
Time (UTC) indicated by a "Z".
Additionally, the canonical representation for midnight is 00:00:00.
3.2.8.3 Constraining facets
time
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.9 date
[Definition:]
The
value space
of
date
consists of top-open intervals of exactly one day in length on the timelines of
dateTime
, 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' 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
dateTime
objects, plus an optional
timezone-valued
timezone property. (As with values of
dateTime
timezones are a
special case of durations.)
Just as a
dateTime
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.
[Definition:]
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) UTC on the
same
date
recoverable timezone
s are
always durations between '+12:00' and '-11:59'. This "timezone normalization"
(which follows automatically from the definition of the
date
value space
) is explained more in
Lexical representation (§3.2.9.1)
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
Note:
For most timezones, either the first moment or last moment of the day (a
dateTime
value, always UTC) 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
UTC. 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.
Note:
See the conformance note in
(§3.2.6)
which
applies to the year part of this datatype as well.
3.2.9.1 Lexical representation
For the following discussion, let the "date portion" of a
dateTime
or
date
object be an object similar to a
dateTime
or
date
object, with similar year, month, and day properties, but no
others, having the same value for these properties as the original
dateTime
or
date
object.
The
lexical space
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
dateTime
. 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?
Note:
The
recoverable timezone
of a
date
will always be
a duration between '+12:00' and '11:59'. Timezone lexical representations, as
explained for
dateTime
, can range from '+14:00' to '-14:00'.
The result is that literals of
date
s with very large or very
negative timezones will map to a "normalized"
date
value with a
recoverable timezone
different from that represented in the original
representation, and a matching difference of +/- 1 day in the
date
itself.
3.2.9.2 Canonical representation
Given a member of the
date
value space
, 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
dateTime
canonical
representation of the interval midpoint (the
dateTime
representation,
truncated on the right to eliminate 'T' and all following characters).
For timezoned values, append the canonical representation of the
recoverable timezone
3.2.10 gYearMonth
[Definition:]
gYearMonth
represents a
specific gregorian month in a specific gregorian year. The
value space
of
gYearMonth
is the set of Gregorian calendar months as defined in § 5.2.1 of
[ISO 8601]
. 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.
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
Order relation on dateTime (§3.2.7.4)
. See also
Adding durations to dateTimes (§E)
. Pairs of
gYearMonth
values with or without time zone indicators are totally ordered.
Note:
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.
Note:
See the conformance note in
(§3.2.6)
which
applies to the year part of this datatype as well.
3.2.10.1 Lexical representation
The lexical representation for
gYearMonth
is the reduced
(right truncated) lexical representation for
dateTime
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
ISO 8601 Date and Time Formats (§D)
3.2.10.2 Constraining facets
gYearMonth
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.11 gYear
[Definition:]
gYear
represents a
gregorian calendar year. The
value space
of
gYear
is the set of Gregorian calendar years as defined in
§ 5.2.1 of
[ISO 8601]
. 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.
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
Order relation on dateTime (§3.2.7.4)
. See also
Adding durations to dateTimes (§E)
. Pairs of
gYear
values with or without time zone indicators are totally ordered.
Note:
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.
Note:
See the conformance note in
(§3.2.6)
which
applies to the year part of this datatype as well.
3.2.11.1 Lexical representation
The lexical representation for
gYear
is the reduced (right
truncated) lexical representation for
dateTime
: CCYY.
No left truncation is allowed. An optional following time
zone qualifier is allowed as for
dateTime
. 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
ISO 8601 Date and Time Formats (§D)
3.2.11.2 Constraining facets
gYear
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.12 gMonthDay
[Definition:]
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
value space
of
gMonthDay
is the set of
calendar
dates
, as defined in § 3 of
[ISO 8601]
. Specifically,
it is a set of one-day long, annually periodic instances.
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
Order relation on dateTime (§3.2.7.4)
. See also
Adding durations to dateTimes (§E)
. Pairs of
gMonthDay
values with or without time zone indicators are totally ordered.
Note:
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.
3.2.12.1 Lexical representation
The lexical representation for
gMonthDay
is the left
truncated lexical representation for
date
: --MM-DD.
An optional following time
zone qualifier is allowed as for
date
No preceding sign is allowed. No other formats are allowed. See also
ISO 8601 Date and Time Formats (§D)
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.
3.2.12.2 Constraining facets
gMonthDay
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.13 gDay
[Definition:]
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
value space
of
gDay
is the space of a set of
calendar
dates
as defined in § 3 of
[ISO 8601]
. Specifically,
it is a set of one-day long, monthly periodic instances.
This datatype can be used to represent a specific day of the month.
To say, for example, that I get my paycheck on the 15th of each month.
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
Order relation on dateTime (§3.2.7.4)
. See also
Adding durations to dateTimes (§E)
. Pairs of
gDay
values with or without time zone indicators are totally ordered.
Note:
Because days in one calendar only rarely correspond
to days 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.
3.2.13.1 Lexical representation
The lexical representation for
gDay
is the left
truncated lexical representation for
date
: ---DD .
An optional following time
zone qualifier is allowed as for
date
. No preceding sign is
allowed. No other formats are allowed. See also
ISO 8601 Date and Time Formats (§D)
3.2.13.2 Constraining facets
gDay
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.14 gMonth
[Definition:]
gMonth
is a gregorian month that recurs every year.
The
value space
of
gMonth
is the space of a set of
calendar
months
as defined in § 3 of
[ISO 8601]
. 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.
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
Order relation on dateTime (§3.2.7.4)
. See also
Adding durations to dateTimes (§E)
. Pairs of
gMonth
values with or without time zone indicators are totally ordered.
Note:
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.
3.2.14.1 Lexical representation
The lexical representation for
gMonth
is the left
and right truncated lexical representation for
date
: --MM.
An optional following time
zone qualifier is allowed as for
date
. No preceding sign is
allowed. No other formats are allowed. See also
ISO 8601 Date and Time Formats (§D)
3.2.14.2 Constraining facets
gMonth
has the
following
constraining facets
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
3.2.15 hexBinary
[Definition:]
hexBinary
represents
arbitrary hex-encoded binary data. The
value space
of
hexBinary
is the set of finite-length sequences of binary
octets.
3.2.15.1 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).
3.2.15.2 Canonical Representation
The canonical representation for
hexBinary
is defined
by prohibiting certain options from the
Lexical Representation (§3.2.15.1)
. Specifically, the lower case
hexadecimal digits ([a-f]) are not allowed.
3.2.15.3 Constraining facets
hexBinary
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.2.16 base64Binary
[Definition:]
base64Binary
represents Base64-encoded arbitrary binary data. The
value space
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
[RFC 2045]
The lexical forms of
base64Binary
values are limited to the 65 characters
of the Base64 Alphabet defined in
[RFC 2045]
, i.e.,
a-z
A-Z
0-9
, the plus sign (+), the forward slash (/) and the
equal sign (=), together with the characters defined in
[XML 1.0 (Second Edition)]
as white space.
No other characters are allowed.
For compatibility with older mail gateways,
[RFC 2045]
suggests that
base64 data should have lines limited to at most 76 characters in length. This
line-length limitation is not mandated in the lexical forms of
base64Binary
data and must not be enforced by XML Schema processors.
The lexical space of
base64Binary
is given by the following grammar
(the notation is that used in
[XML 1.0 (Second Edition)]
); 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.
Note:
The above definition of the lexical space is more restrictive than that
given in
[RFC 2045]
as regards whitespace -- this is not an issue
in practice. Any string compatible with the RFC can occur in
an element or attribute validated by this type, because the
whiteSpace
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 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 '=='))?
Note:
For some values the canonical form defined above does not conform to
[RFC 2045]
, which requires
breaking with linefeeds at appropriate intervals.
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:
[RFC 2045]
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
[XML 1.0 (Second Edition)]
3.2.16.1 Constraining facets
base64Binary
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.2.17 anyURI
[Definition:]
anyURI
represents a Uniform Resource Identifier Reference
(URI). An
anyURI
value can be absolute or relative, and may
have an optional fragment identifier (i.e., it may be a URI Reference). This
type should be used to specify the intention that the value fulfills
the role of a URI as defined by
[RFC 2396]
, as amended by
[RFC 2732]
The mapping from
anyURI
values to URIs is as
defined by the URI reference escaping procedure
defined in
Section 5.4
Locator Attribute
of
[XML Linking Language]
(see also Section 8
Character Encoding in URI References
of
[Character Model]
). 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
[RFC 2396]
, as amended by
[RFC 2732]
where appropriate to identify resources.
Note:
Section 5.4
Locator Attribute
of
[XML Linking Language]
requires that relative URI references be absolutized
as defined in
[XML Base]
before use. This is an XLink-specific
requirement and is not appropriate for XML Schema, since neither the
lexical space
nor the
value space
of the
anyURI
type are restricted to absolute URIs. Accordingly
absolutization must not be performed by schema processors as part of schema
validation.
Note:
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
[RFC 2396]
(as amended by
[RFC 2732]
in this matter: such rules and restrictions are not part of type validity
and are not checked by
minimally conforming
processors.
Thus in practice the above definition imposes only very modest obligations
on
minimally conforming
processors.
3.2.17.1 Lexical representation
The
lexical space
of
anyURI
is
finite-length character sequences which, when the algorithm defined in
Section 5.4 of
[XML Linking Language]
is applied to them, result in strings
which are legal URIs according to
[RFC 2396]
, as amended by
[RFC 2732]
Note:
Spaces are, in principle, allowed in the
lexical space
of
anyURI
, however, their use is highly discouraged
(unless they are encoded by %20).
3.2.17.2 Constraining facets
anyURI
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.2.18 QName
[Definition:]
QName
represents
XML qualified names
The
value space
of
QName
is the set of
tuples {
namespace name
local part
},
where
namespace name
is an
anyURI
and
local part
is
an
NCName
The
lexical space
of
QName
is the set
of strings that
match
the
QName
production of
[Namespaces in XML]
Note:
The mapping between literals in the
lexical space
and
values in the
value space
of
QName
requires
a namespace declaration to be in scope for the context in which
QName
is used.
3.2.18.1 Constraining facets
QName
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
The use of
length
minLength
and
maxLength
on datatypes
derived
from
QName
is
deprecated. Future versions of this specification may
remove these facets for this datatype.
3.2.19 NOTATION
[Definition:]
NOTATION
represents the
NOTATION
attribute
type from
[XML 1.0 (Second Edition)]
. The
value space
of
NOTATION
is the set of
QName
of notations declared in the current schema.
The
lexical space
of
NOTATION
is the set
of all names of
notations
declared in the current schema (in the form of
QName
s).
Schema Component Constraint: enumeration facet value required for NOTATION
It is an
error
for
NOTATION
to be used directly in a schema. Only datatypes that are
derived
from
NOTATION
by
specifying a value for
enumeration
can be used
in a schema.
For compatibility (see
Terminology (§1.4)
NOTATION
should be used only on attributes
and should only be used in schemas with no
target namespace.
3.2.19.1 Constraining facets
NOTATION
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
The use of
length
minLength
and
maxLength
on datatypes
derived
from
NOTATION
is
deprecated. Future versions of this specification may
remove these facets for this datatype.
3.3 Derived datatypes
3.3.1
normalizedString
3.3.2
token
3.3.3
language
3.3.4
NMTOKEN
3.3.5
NMTOKENS
3.3.6
Name
3.3.7
NCName
3.3.8
ID
3.3.9
IDREF
3.3.10
IDREFS
3.3.11
ENTITY
3.3.12
ENTITIES
3.3.13
integer
3.3.14
nonPositiveInteger
3.3.15
negativeInteger
3.3.16
long
3.3.17
int
3.3.18
short
3.3.19
byte
3.3.20
nonNegativeInteger
3.3.21
unsignedLong
3.3.22
unsignedInt
3.3.23
unsignedShort
3.3.24
unsignedByte
3.3.25
positiveInteger
This section gives conceptual definitions for all
built-in
derived
datatypes
defined by this specification. The XML representation used to define
derived
datatypes (whether
built-in
or
user-derived
) is
given in section
XML Representation of Simple Type Definition Schema Components (§4.1.2)
and the complete
definitions of the
built-in
derived
datatypes are provided in Appendix A
Schema for Datatype Definitions (normative) (§A)
3.3.1 normalizedString
[Definition:]
normalizedString
represents white space normalized strings.
The
value space
of
normalizedString
is the
set of strings that do not
contain the carriage return (#xD), line feed (#xA) nor tab (#x9) characters.
The
lexical space
of
normalizedString
is the
set of strings that do not
contain the carriage return (#xD),
line feed (#xA)
nor tab (#x9) characters.
The
base type
of
normalizedString
is
string
3.3.1.1 Constraining facets
normalizedString
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.3.1.2 Derived datatypes
The following
built-in
datatypes are
derived
from
normalizedString
token
3.3.2 token
[Definition:]
token
represents tokenized strings.
The
value space
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
lexical space
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
base type
of
token
is
normalizedString
3.3.2.1 Constraining facets
token
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.3.2.2 Derived datatypes
The following
built-in
datatypes are
derived
from
token
language
NMTOKEN
Name
3.3.3 language
[Definition:]
language
represents natural language identifiers as defined by
by
[RFC 3066]
The
value space
of
language
is the
set of all strings that are valid language identifiers as defined
[RFC 3066]
The
lexical space
of
language
is the set of all strings that
conform to the pattern
[a-zA-Z]{1,8}(-[a-zA-Z0-9]{1,8})*
The
base type
of
language
is
token
3.3.3.1 Constraining facets
language
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.3.4 NMTOKEN
[Definition:]
NMTOKEN
represents
the
NMTOKEN attribute type
from
[XML 1.0 (Second Edition)]
. The
value space
of
NMTOKEN
is the set of tokens that
match
the
Nmtoken
production in
[XML 1.0 (Second Edition)]
. The
lexical space
of
NMTOKEN
is the set of strings that
match
the
Nmtoken
production in
[XML 1.0 (Second Edition)]
. The
base type
of
NMTOKEN
is
token
For compatibility (see
Terminology (§1.4)
NMTOKEN
should be used only on attributes.
3.3.4.1 Constraining facets
NMTOKEN
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.3.4.2 Derived datatypes
The following
built-in
datatypes are
derived
from
NMTOKEN
NMTOKENS
3.3.5 NMTOKENS
[Definition:]
NMTOKENS
represents the
NMTOKENS attribute
type
from
[XML 1.0 (Second Edition)]
. The
value space
of
NMTOKENS
is the set of finite, non-zero-length sequences of
NMTOKEN
s. The
lexical space
of
NMTOKENS
is the set of space-separated lists of tokens,
of which each token is in the
lexical space
of
NMTOKEN
. The
itemType
of
NMTOKENS
is
NMTOKEN
For compatibility (see
Terminology (§1.4)
NMTOKENS
should be used only on attributes.
3.3.5.1 Constraining facets
NMTOKENS
has the
following
constraining facets
length
minLength
maxLength
enumeration
whiteSpace
pattern
3.3.6 Name
[Definition:]
Name
represents
XML Names
The
value space
of
Name
is
the set of all strings which
match
the
Name
production of
[XML 1.0 (Second Edition)]
. The
lexical space
of
Name
is the set of all strings which
match
the
Name
production of
[XML 1.0 (Second Edition)]
. The
base type
of
Name
is
token
3.3.6.1 Constraining facets
Name
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.3.6.2 Derived datatypes
The following
built-in
datatypes are
derived
from
Name
NCName
3.3.7 NCName
[Definition:]
NCName
represents XML
"non-colonized" Names. The
value space
of
NCName
is the set of all strings which
match
the
NCName
production of
[Namespaces in XML]
. The
lexical space
of
NCName
is the set of all strings which
match
the
NCName
production of
[Namespaces in XML]
. The
base type
of
NCName
is
Name
3.3.7.1 Constraining facets
NCName
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.3.7.2 Derived datatypes
The following
built-in
datatypes are
derived
from
NCName
ID
IDREF
ENTITY
3.3.8 ID
[Definition:]
ID
represents the
ID attribute type
from
[XML 1.0 (Second Edition)]
. The
value space
of
ID
is the set of all strings that
match
the
NCName
production in
[Namespaces in XML]
. The
lexical space
of
ID
is the set of all
strings that
match
the
NCName
production in
[Namespaces in XML]
The
base type
of
ID
is
NCName
For compatibility (see
Terminology (§1.4)
ID
should be used only on attributes.
3.3.8.1 Constraining facets
ID
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.3.9 IDREF
[Definition:]
IDREF
represents the
IDREF attribute type
from
[XML 1.0 (Second Edition)]
. The
value space
of
IDREF
is the set of all strings that
match
the
NCName
production in
[Namespaces in XML]
. The
lexical space
of
IDREF
is the set of
strings that
match
the
NCName
production in
[Namespaces in XML]
The
base type
of
IDREF
is
NCName
For compatibility (see
Terminology (§1.4)
) this datatype
should be used only on attributes.
3.3.9.1 Constraining facets
IDREF
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.3.9.2 Derived datatypes
The following
built-in
datatypes are
derived
from
IDREF
IDREFS
3.3.10 IDREFS
[Definition:]
IDREFS
represents the
IDREFS attribute type
from
[XML 1.0 (Second Edition)]
. The
value space
of
IDREFS
is the set of finite, non-zero-length sequences of
IDREF
s.
The
lexical space
of
IDREFS
is the
set of space-separated lists of tokens, of which each token is in the
lexical space
of
IDREF
The
itemType
of
IDREFS
is
IDREF
For compatibility (see
Terminology (§1.4)
IDREFS
should be used only on attributes.
3.3.10.1 Constraining facets
IDREFS
has the
following
constraining facets
length
minLength
maxLength
enumeration
whiteSpace
pattern
3.3.11 ENTITY
[Definition:]
ENTITY
represents the
ENTITY
attribute type from
[XML 1.0 (Second Edition)]
. The
value space
of
ENTITY
is the set of all strings that
match
the
NCName
production in
[Namespaces in XML]
and have been declared as an
unparsed entity
in
document type definition
The
lexical space
of
ENTITY
is the set
of all strings that
match
the
NCName
production in
[Namespaces in XML]
The
base type
of
ENTITY
is
NCName
Note:
The
value space
of
ENTITY
is scoped
to a specific instance document.
For compatibility (see
Terminology (§1.4)
ENTITY
should be used only on attributes.
3.3.11.1 Constraining facets
ENTITY
has the
following
constraining facets
length
minLength
maxLength
pattern
enumeration
whiteSpace
3.3.11.2 Derived datatypes
The following
built-in
datatypes are
derived
from
ENTITY
ENTITIES
3.3.12 ENTITIES
[Definition:]
ENTITIES
represents the
ENTITIES attribute
type
from
[XML 1.0 (Second Edition)]
. The
value space
of
ENTITIES
is the set of finite, non-zero-length sequences of
ENTITY
s that have been declared as
unparsed entities
in a
document type definition
The
lexical space
of
ENTITIES
is the
set of space-separated lists of tokens, of which each token is in the
lexical space
of
ENTITY
The
itemType
of
ENTITIES
is
ENTITY
Note:
The
value space
of
ENTITIES
is scoped
to a specific instance document.
For compatibility (see
Terminology (§1.4)
ENTITIES
should be used only on attributes.
3.3.12.1 Constraining facets
ENTITIES
has the
following
constraining facets
length
minLength
maxLength
enumeration
whiteSpace
pattern
3.3.13 integer
[Definition:]
integer
is
derived
from
decimal
by fixing the
value of
fractionDigits
to be 0and
disallowing the trailing decimal point.
This results in the standard
mathematical concept of the integer numbers. The
value space
of
integer
is the infinite
set {...,-2,-1,0,1,2,...}. The
base type
of
integer
is
decimal
3.3.13.1 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.
3.3.13.2 Canonical representation
The canonical representation for
integer
is defined
by prohibiting certain options from the
Lexical representation (§3.3.13.1)
. Specifically, the preceding optional "+" sign is prohibited and leading zeroes are prohibited.
3.3.13.3 Constraining facets
integer
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.13.4 Derived datatypes
The following
built-in
datatypes are
derived
from
integer
nonPositiveInteger
long
nonNegativeInteger
3.3.14 nonPositiveInteger
[Definition:]
nonPositiveInteger
is
derived
from
integer
by setting the value of
maxInclusive
to be 0. This results in the
standard mathematical concept of the non-positive integers.
The
value space
of
nonPositiveInteger
is the infinite set {...,-2,-1,0}. The
base type
of
nonPositiveInteger
is
integer
3.3.14.1 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.
3.3.14.2 Canonical representation
The canonical representation for
nonPositiveInteger
is defined
by prohibiting certain options from the
Lexical representation (§3.3.14.1)
In the canonical form for zero, the sign must be
omitted. Leading zeroes are prohibited.
3.3.14.3 Constraining facets
nonPositiveInteger
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.14.4 Derived datatypes
The following
built-in
datatypes are
derived
from
nonPositiveInteger
negativeInteger
3.3.15 negativeInteger
[Definition:]
negativeInteger
is
derived
from
nonPositiveInteger
by setting the value of
maxInclusive
to be -1. This results in the
standard mathematical concept of the negative integers. The
value space
of
negativeInteger
is the infinite set {...,-2,-1}. The
base type
of
negativeInteger
is
nonPositiveInteger
3.3.15.1 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.
3.3.15.2 Canonical representation
The canonical representation for
negativeInteger
is defined
by prohibiting certain options from the
Lexical representation (§3.3.15.1)
. Specifically, leading zeroes are prohibited.
3.3.15.3 Constraining facets
negativeInteger
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.16 long
[Definition:]
long
is
derived
from
integer
by setting the
value of
maxInclusive
to be 9223372036854775807
and
minInclusive
to be -9223372036854775808.
The
base type
of
long
is
integer
3.3.16.1 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.
3.3.16.2 Canonical representation
The canonical representation for
long
is defined
by prohibiting certain options from the
Lexical representation (§3.3.16.1)
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
3.3.16.3 Constraining facets
long
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.16.4 Derived datatypes
The following
built-in
datatypes are
derived
from
long
int
3.3.17 int
[Definition:]
int
is
derived
from
long
by setting the
value of
maxInclusive
to be 2147483647 and
minInclusive
to be -2147483648. The
base type
of
int
is
long
3.3.17.1 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.
3.3.17.2 Canonical representation
The canonical representation for
int
is defined
by prohibiting certain options from the
Lexical representation (§3.3.17.1)
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
3.3.17.3 Constraining facets
int
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.17.4 Derived datatypes
The following
built-in
datatypes are
derived
from
int
short
3.3.18 short
[Definition:]
short
is
derived
from
int
by setting the
value of
maxInclusive
to be 32767 and
minInclusive
to be -32768. The
base type
of
short
is
int
3.3.18.1 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.
3.3.18.2 Canonical representation
The canonical representation for
short
is defined
by prohibiting certain options from the
Lexical representation (§3.3.18.1)
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
3.3.18.3 Constraining facets
short
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.18.4 Derived datatypes
The following
built-in
datatypes are
derived
from
short
byte
3.3.19 byte
[Definition:]
byte
is
derived
from
short
by setting the value of
maxInclusive
to be 127
and
minInclusive
to be -128.
The
base type
of
byte
is
short
3.3.19.1 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.
3.3.19.2 Canonical representation
The canonical representation for
byte
is defined
by prohibiting certain options from the
Lexical representation (§3.3.19.1)
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
3.3.19.3 Constraining facets
byte
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.20 nonNegativeInteger
[Definition:]
nonNegativeInteger
is
derived
from
integer
by setting the value of
minInclusive
to be 0. This results in the
standard mathematical concept of the non-negative integers. The
value space
of
nonNegativeInteger
is the infinite set {0,1,2,...}. The
base type
of
nonNegativeInteger
is
integer
3.3.20.1 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.
3.3.20.2 Canonical representation
The canonical representation for
nonNegativeInteger
is defined
by prohibiting certain options from the
Lexical representation (§3.3.20.1)
. Specifically, the
the optional "+" sign is prohibited and leading zeroes are prohibited.
3.3.20.3 Constraining facets
nonNegativeInteger
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.20.4 Derived datatypes
The following
built-in
datatypes are
derived
from
nonNegativeInteger
unsignedLong
positiveInteger
3.3.21 unsignedLong
[Definition:]
unsignedLong
is
derived
from
nonNegativeInteger
by setting the value of
maxInclusive
to be 18446744073709551615.
The
base type
of
unsignedLong
is
nonNegativeInteger
3.3.21.1 Lexical representation
unsignedLong
has a lexical representation consisting
of a finite-length sequence of decimal digits (#x30-#x39).
For example: 0,
12678967543233, 100000.
3.3.21.2 Canonical representation
The canonical representation for
unsignedLong
is defined
by prohibiting certain options from the
Lexical representation (§3.3.21.1)
. Specifically,
leading zeroes are prohibited.
3.3.21.3 Constraining facets
unsignedLong
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.21.4 Derived datatypes
The following
built-in
datatypes are
derived
from
unsignedLong
unsignedInt
3.3.22 unsignedInt
[Definition:]
unsignedInt
is
derived
from
unsignedLong
by setting the value of
maxInclusive
to be 4294967295. The
base type
of
unsignedInt
is
unsignedLong
3.3.22.1 Lexical representation
unsignedInt
has a lexical representation consisting
of a finite-length
sequence of decimal digits (#x30-#x39). For example: 0,
1267896754, 100000.
3.3.22.2 Canonical representation
The canonical representation for
unsignedInt
is defined
by prohibiting certain options from the
Lexical representation (§3.3.22.1)
. Specifically,
leading zeroes are prohibited.
3.3.22.3 Constraining facets
unsignedInt
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.22.4 Derived datatypes
The following
built-in
datatypes are
derived
from
unsignedInt
unsignedShort
3.3.23 unsignedShort
[Definition:]
unsignedShort
is
derived
from
unsignedInt
by setting the value of
maxInclusive
to be 65535. The
base type
of
unsignedShort
is
unsignedInt
3.3.23.1 Lexical representation
unsignedShort
has a lexical representation consisting
of a finite-length
sequence of decimal digits (#x30-#x39).
For example: 0,
12678, 10000.
3.3.23.2 Canonical representation
The canonical representation for
unsignedShort
is defined
by prohibiting certain options from the
Lexical representation (§3.3.23.1)
. Specifically, the
leading zeroes are prohibited.
3.3.23.3 Constraining facets
unsignedShort
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.23.4 Derived datatypes
The following
built-in
datatypes are
derived
from
unsignedShort
unsignedByte
3.3.24 unsignedByte
[Definition:]
unsignedByte
is
derived
from
unsignedShort
by setting the value of
maxInclusive
to be 255. The
base type
of
unsignedByte
is
unsignedShort
3.3.24.1 Lexical representation
unsignedByte
has a lexical representation consisting
of a finite-length
sequence of decimal digits (#x30-#x39).
For example: 0,
126, 100.
3.3.24.2 Canonical representation
The canonical representation for
unsignedByte
is defined
by prohibiting certain options from the
Lexical representation (§3.3.24.1)
. Specifically,
leading zeroes are prohibited.
3.3.24.3 Constraining facets
unsignedByte
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
3.3.25 positiveInteger
[Definition:]
positiveInteger
is
derived
from
nonNegativeInteger
by setting the value of
minInclusive
to be 1. This results in the standard
mathematical concept of the positive integer numbers.
The
value space
of
positiveInteger
is the infinite set {1,2,...}. The
base type
of
positiveInteger
is
nonNegativeInteger
3.3.25.1 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.
3.3.25.2 Canonical representation
The canonical representation for
positiveInteger
is defined
by prohibiting certain options from the
Lexical representation (§3.3.25.1)
. Specifically, the
optional "+" sign is prohibited and leading zeroes are prohibited.
3.3.25.3 Constraining facets
positiveInteger
has the
following
constraining facets
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
4 Datatype components
The following sections provide full details on the properties and
significance of each kind of schema component involved in datatype
definitions. For each property, the kinds of values it is allowed to have is
specified. Any property not identified as optional is required to
be present; optional properties which are not present have
absent
as their value.
Any property identified as a having a set, subset or
list
value may have an empty value unless this is explicitly ruled out: this is
not the same as
absent
Any property value identified as a superset or a subset of some set may
be equal to that set, unless a proper superset or subset is explicitly
called for.
For more information on the notion of datatype (schema) components,
see
Schema Component Details
of
[XML Schema Part 1: Structures]
4.1 Simple Type Definition
4.1.1
The Simple Type Definition Schema Component
4.1.2
XML Representation of Simple Type Definition Schema Components
4.1.3
Constraints on XML Representation of Simple Type Definition
4.1.4
Simple Type Definition Validation Rules
4.1.5
Constraints on Simple Type Definition Schema Components
4.1.6
Simple Type Definition for anySimpleType
Simple Type definitions provide for:
Establishing the
value space
and
lexical space
of a datatype, through
the combined set of
constraining facet
s specified
in the definition;
Attaching a unique name (actually a
QName
) to the
value space
and
lexical space
4.1.1 The Simple Type Definition Schema Component
The Simple Type Definition schema component has the following properties:
Schema Component
Simple Type Definition
{name}
Optional. An NCName as defined by
[Namespaces in XML]
{target namespace}
Either
absent
or a
namespace name, as defined in
[Namespaces in XML]
{variety}
One of {
atomic
list
union
}. Depending on the
value of
{variety}
, further properties are defined as follows:
atomic
{primitive type definition}
built-in
primitive
datatype definition).
list
{item type definition}
An
atomic
or
union
simple type definition.
union
{member type definitions}
A non-empty sequence of simple type definitions.
{facets}
A possibly empty set of
Facets (§2.4)
{fundamental facets}
A set of
Fundamental facets (§2.4.1)
{base type definition}
If the datatype has been
derived
by
restriction
then the
Simple Type Definition
component
from which it is
derived
, otherwise
the
Simple Type Definition for anySimpleType (§4.1.6)
{final}
A subset of
{restriction, list, union}
{annotation}
Optional. An
annotation
Datatypes are identified by their
{name}
and
{target namespace}
. Except
for anonymous datatypes (those with no
{name}
),
datatype definitions
must
be uniquely identified
within a schema.
If
{variety}
is
atomic
then the
value space
of the datatype defined will
be a subset of the
value space
of
{base type definition}
(which is a subset of the
value space
of
{primitive type definition}
).
If
{variety}
is
list
then the
value space
of the datatype defined will
be the set of finite-length sequence of values from the
value space
of
{item type definition}
If
{variety}
is
union
then the
value space
of the datatype defined will be the
union of the
value space
s of each datatype in
{member type definitions}
If
{variety}
is
atomic
then the
{variety}
of
{base type definition}
must be
atomic
If
{variety}
is
list
then the
{variety}
of
{item type definition}
must be either
atomic
or
union
If
{variety}
is
union
then
{member type definitions}
must be a list of datatype definitions.
The value of
{facets}
consists of the set of
facet
s specified directly in the datatype definition
unioned with the possibly empty set of
{facets}
of
{base type definition}
The value of
{fundamental facets}
consists of the set of
fundamental facet
s and their values.
If
{final}
is the empty set then the type can be used
in deriving other types; the explicit values
restriction
list
and
union
prevent further derivations
by
restriction
list
and
union
respectively.
4.1.2 XML Representation of Simple Type Definition Schema Components
The XML representation for a
Simple Type Definition
schema component
is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
simpleType
Element Information Item
#all
| List of (
list
union
restriction
))
id =
ID
name
NCName
{any attributes with non-schema namespace . . .}
Content:
annotation
?, (
restriction
list
union
))
Datatype Definition
Schema Component
Property
Representation
{name}
The
actual value
of the
name
[attribute]
, if present,
otherwise
null
{final}
A set corresponding to the
actual value
of the
final
[attribute]
, if present, otherwise
the
actual value
of the
finalDefault
[attribute]
of the ancestor
schema
element information item, if present, otherwise the empty string, as follows:
the empty string
the empty set;
#all
{restriction, list, union}
otherwise
a set with members drawn from the set above, each being present or
absent depending on whether the string contains an equivalently named
space-delimited substring.
Note:
Although the
finalDefault
[attribute]
of
schema
may include
values other than
restriction
list
or
union
, those values
are ignored in the determination of
{final}
{target namespace}
The
actual value
of the
targetNamespace
[attribute]
of the parent
schema
element information item.
{annotation}
The annotation corresponding to the
element information item in the
[children]
, if present, otherwise
null
derived
datatype can be
derived
from a
primitive
datatype or another
derived
datatype by one of three means:
by
restriction
, by
list
or by
union
4.1.2.1 Derivation by restriction
XML Representation Summary
restriction
Element Information Item
QName
id =
ID
{any attributes with non-schema namespace . . .}
Content:
annotation
?, (
simpleType
?, (
minExclusive
minInclusive
maxExclusive
maxInclusive
totalDigits
fractionDigits
length
minLength
maxLength
enumeration
whiteSpace
pattern
)*))
Simple Type Definition
Schema Component
Property
Representation
{variety}
The
actual value
of
{variety}
of
{base type definition}
{facets}
The union of the set of
Facets (§2.4)
components
resolved to by the facet
[children]
merged with
{facets}
from
{base type definition}
, subject to the Facet Restriction Valid
constraints specified in
Facets (§2.4)
{base type definition}
The
Simple Type Definition
component resolved to by the
actual value
of the
base
[attribute]
or the
[children]
whichever is present.
Example
An electronic commerce schema might define a datatype called
Sku
(the barcode number that appears on products) from the
built-in
datatype
string
by
supplying a value for the
pattern
facet.
In this case,
Sku
is the name of the new
user-derived
datatype,
string
is
its
base type
and
pattern
is the facet.
4.1.2.2 Derivation by list
XML Representation Summary
list
Element Information Item
ID
itemType =
QName
{any attributes with non-schema namespace . . .}
Content:
annotation
?,
simpleType
?)
Simple Type Definition
Schema Component
Property
Representation
{variety}
list
{item type definition}
The
Simple Type Definition
component resolved to by the
actual value
of the
itemType
[attribute]
or the
[children]
whichever is present.
list
datatype must be
derived
from an
atomic
or a
union
datatype,
known as the
itemType
of the
list
datatype.
This yields a datatype whose
value space
is composed of
finite-length sequences of values from the
value space
of the
itemType
and whose
lexical space
is
composed of space-separated lists of literals of the
itemType
Example
A system might want to store lists of floating point values.
In this case,
listOfFloat
is the name of the new
user-derived
datatype,
float
is its
itemType
and
list
is the
derivation method.
As mentioned in
List datatypes (§2.5.1.2)
when a datatype is
derived
from a
list
datatype, the following
constraining facet
s can be used:
length
maxLength
minLength
enumeration
pattern
whiteSpace
regardless of the
constraining facet
s that are applicable
to the
atomic
datatype that serves as the
itemType
of the
list
For each of
length
maxLength
and
minLength
, the
unit of length
is measured in number of list items.
The value of
whiteSpace
is fixed to the value
collapse
4.1.2.3 Derivation by union
XML Representation Summary
union
Element Information Item
ID
memberTypes = List of
QName
{any attributes with non-schema namespace . . .}
Content:
annotation
?,
simpleType
*)
Simple Type Definition
Schema Component
Property
Representation
{variety}
union
{member type definitions}
The sequence of
Simple Type Definition
components resolved to by the
items in the
actual value
of the
memberTypes
[attribute]
, if any,
in order, followed by the
Simple Type Definition
components resolved to by the
[children]
, if any, in order.
If
{variety}
is
union
for
any
Simple Type Definition
components resolved to above, then
the
Simple Type Definition
is replaced by its
{member type definitions}
union
datatype can be
derived
from one or more
atomic
list
or
other
union
datatypes, known as the
memberTypes
of that
union
datatype.
Example
As an example, taken from a typical display oriented text markup language,
one might want to express font sizes as an integer between 8 and 72, or with
one of the tokens "small", "medium" or "large". The
union
type definition below would accomplish that.
A header
this is a test
As mentioned in
Union datatypes (§2.5.1.3)
when a datatype is
derived
from a
union
datatype, the only following
constraining facet
s can be used:
pattern
enumeration
regardless of the
constraining facet
s that are
applicable to the datatypes that participate in the
union
4.1.3 Constraints on XML Representation of Simple Type Definition
Schema Representation Constraint: Single Facet Value
Unless otherwise specifically allowed by this specification
Multiple patterns (§4.3.4.3)
and
Multiple enumerations (§4.3.5.3)
) any given
constraining facet
can only be specifed once within
a single derivation step.
Schema Representation Constraint: itemType attribute or simpleType child
Either the
itemType
[attribute]
or the
[child]
of the
element
must be present, but not both.
Schema Representation Constraint: base attribute or simpleType child
Either the
base
[attribute]
or the
simpleType
[child]
of the
element must be present, but not both.
Schema Representation Constraint: memberTypes attribute or simpleType children
Either the
memberTypes
[attribute]
of the
element must be non-empty or
there must be at least one
simpleType
[child]
4.1.4 Simple Type Definition Validation Rules
Validation Rule: Facet Valid
A value in a
value space
is facet-valid with
respect to a
constraining facet
component if:
the value is facet-valid with respect to the particular
constraining facet
as specified below.
Validation Rule: Datatype Valid
A string is datatype-valid with respect to a datatype definition if:
it
match
es a literal in the
lexical space
of the datatype, determined as follows:
1.1
if
pattern
is a member of
{facets}
then the string must be
pattern valid (§4.3.4.4)
1.2
if
pattern
is not a member of
{facets}
then
1.2.1
if
{variety}
is
atomic
then
the string must
match
a literal in the
lexical space
of
{base type definition}
1.2.2
if
{variety}
is
list
then the string must
be a sequence of space-separated tokens, each of which
match
es a literal in the
lexical space
of
{item type definition}
1.2.3
if
{variety}
is
union
then
the string must
match
a literal in the
lexical space
of at least one member of
{member type definitions}
the value denoted by the literal
match
ed in the previous step
is a member of the
value space
of the datatype, as determined
by it being
Facet Valid (§4.1.4)
with respect to each member of
{facets}
(except
for
pattern
).
4.1.5 Constraints on Simple Type Definition Schema Components
Schema Component Constraint: applicable facets
The
constraining facet
s which are allowed
to be members of
{facets}
are dependent on
{base type definition}
as specified in the following table:
{base type definition}
applicable
{facets}
If
{variety}
is
list
then
[all datatypes]
length
minLength
maxLength
pattern
enumeration
whiteSpace
If
{variety}
is
union
, then
[all datatypes]
pattern
enumeration
else if
{variety}
is
atomic
, then
string
length
minLength
maxLength
pattern
enumeration
whiteSpace
boolean
pattern
whiteSpace
float
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
double
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
decimal
totalDigits
fractionDigits
pattern
whiteSpace
enumeration
maxInclusive
maxExclusive
minInclusive
minExclusive
duration
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
dateTime
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
time
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
date
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
gYearMonth
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
gYear
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
gMonthDay
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
gDay
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
gMonth
pattern
enumeration
whiteSpace
maxInclusive
maxExclusive
minInclusive
minExclusive
hexBinary
length
minLength
maxLength
pattern
enumeration
whiteSpace
base64Binary
length
minLength
maxLength
pattern
enumeration
whiteSpace
anyURI
length
minLength
maxLength
pattern
enumeration
whiteSpace
QName
length
minLength
maxLength
pattern
enumeration
whiteSpace
NOTATION
length
minLength
maxLength
pattern
enumeration
whiteSpace
Schema Component Constraint: list of atomic
If
{variety}
is
list
, then
the
{variety}
of
{item type definition}
must
be
atomic
or
union
Schema Component Constraint: no circular unions
If
{variety}
is
union
then
it is an
error
if
{name}
and
{target namespace}
match
{name}
and
{target namespace}
of any member of
{member type definitions}
4.1.6 Simple Type Definition for anySimpleType
There is a simple type definition nearly equivalent to the simple version
of the
ur-type definition
present
in every schema by definition. It has the following properties:
Schema Component
anySimpleType
{name}
anySimpleType
{target namespace}
{basetype definition}
the ur-type definition
{final}
the empty set
{variety}
absent
4.2 Fundamental Facets
4.2.1
equal
4.2.2
ordered
4.2.3
bounded
4.2.4
cardinality
4.2.5
numeric
4.2.1 equal
Every
value space
supports the notion of equality,
with the following rules:
for any
and
in
the
value space
either
is equal to
denoted
a = b
, or
is not equal to
, denoted
a != b
there is no pair
and
from the
value space
such that both
a = b
and
a != b
for all
in the
value space
a = a
for any
and
in the
value space
a = b
if and only if
b = a
for any
and
in the
value space
if
a = b
and
b = c
, then
a = c
for any
and
in the
value space
if
a = b
, then
and
cannot be distinguished
(i.e., equality is identity)
the
value space
s of all
primitive
datatypes are disjoint (they do not
share any values)
On every datatype, the operation Equal is defined in terms of the equality
property of the
value space
: for any values
a, b
drawn from the
value space
Equal(a,b)
is
true if
a = b
, and false otherwise.
Note that in consequence of the above:
given
value space
and
value space
where
and
are disjoint,
every pair of values
from
and
from
a != b
two values which are members of the
value space
of the same
primitive
datatype may always be
compared with each other
if a datatype
is
derived
by
union
from
memberTypes
A, B, ...
then the
value space
of
is the
union of
value space
s of its
memberTypes
A, B, ...
Some values in the
value space
of
are also values in the
value space
of
Other values in the
value space
of
will be values in the
value space
of
and so on.
Values in the
value space
of
which are also in the
value space
of
can be compared with other values in the
value space
of
according
to the above rules. Similarly for values of type
and
and all the other
memberTypes
if a datatype
T'
is
derived
by
restriction
from an atomic datatype
then the
value space
of
T'
is
a subset of the
value space
of
Values in the
value space
s of
and
T'
can be compared
according to the above rules
if datatypes
T'
and
T''
are
derived
by
restriction
from a
common atomic ancestor
then the
value space
s of
T'
and
T''
may overlap. Values in the
value space
of
T'
and
T''
can be
compared according to the above rules
Note:
There is no schema component corresponding to the
equal
fundamental facet
4.2.2 ordered
[Definition:]
An
order relation
on a
value space
is a mathematical relation that imposes a
total order
or a
partial order
on the
members of the
value space
[Definition:]
value space
, and hence a datatype, is said to be
ordered
if there exists an
order-relation
defined for that
value space
[Definition:]
partial order
is an
order-relation
that is
irreflexive
asymmetric
and
transitive
partial order
has the following properties:
for no
in the
value space
a < a
(irreflexivity)
for all
and
in the
value space
a < b
implies not(
b < a
(asymmetry)
for all
and
in the
value space
a < b
and
b < c
implies
a < c
(transitivity)
The notation
a <> b
is used to indicate the
case when
a != b
and neither
a < b
nor
b < a
For any values
and
from different
primitive
value space
s,
a <> b
[Definition:]
When
a <> b
and
are
incomparable
[Definition:]
otherwise they are
comparable
[Definition:]
total order
is an
partial order
such that for no
and
is it the case that
a <> b
total order
has all of the properties specified
above for
partial order
, plus
the following property:
for all
and
in the
value space
either
a < b
or
b < a
or
a = b
Note:
The fact that this specification does not define an
order-relation
for some datatype does not
mean that some other application cannot treat that datatype as
being ordered by imposing its own order relation.
ordered
provides for:
indicating whether an
order-relation
is
defined on a
value space
, and if so,
whether that
order-relation
is
partial order
or a
total order
4.2.2.1 The ordered Schema Component
Schema Component
ordered
{value}
One of
{false, partial, total}
{value}
depends on
{variety}
{facets}
and
{member type definitions}
in the
Simple Type Definition
component in which a
ordered
component appears as a member of
{fundamental facets}
When
{variety}
is
atomic
{value}
is inherited from
{value}
of
{base type definition}
For all
primitive
types
{value}
is as specified in the table in
Fundamental Facets (§C.1)
When
{variety}
is
list
{value}
is
false
When
{variety}
is
union
{value}
is
partial
unless one of the
following:
If every member of
{member type definitions}
is derived from
a common ancestor other than the simple ur-type, then
{value}
is the same as that ancestor's
ordered
facet
If every member of
{member type definitions}
has a
{value}
of
false
for the
ordered
facet, then
{value}
is
false
4.2.3 bounded
[Definition:]
A value
in an
ordered
value space
is said to be an
inclusive upper bound
of a
value space
(where
is a subset of
if for all
in
>=
[Definition:]
A value
in an
ordered
value space
is said to be an
exclusive upper bound
of a
value space
(where
is a subset of
if for all
in
[Definition:]
A value
in an
ordered
value space
is said to be an
inclusive lower bound
of a
value space
(where
is a subset of
if for all
in
<=
[Definition:]
A value
in an
ordered
value space
is said to be an
exclusive lower bound
of a
value space
(where
is a subset of
if for all
in
[Definition:]
A datatype is
bounded
if its
value space
has either an
inclusive upper bound
or an
exclusive upper bound
and either an
inclusive lower bound
or
an
exclusive lower bound
bounded
provides for:
indicating whether a
value space
is
bounded
4.2.3.1 The bounded Schema Component
Schema Component
bounded
{value}
boolean
{value}
depends on
{variety}
{facets}
and
{member type definitions}
in the
Simple Type Definition
component in which a
bounded
component appears as a member of
{fundamental facets}
When
{variety}
is
atomic
if one of
minInclusive
or
minExclusive
and one of
maxInclusive
or
maxExclusive
are among
{facets}
, then
{value}
is
true
; else
{value}
is
false
When
{variety}
is
list
if
length
or both of
minLength
and
maxLength
are among
{facets}
, then
{value}
is
true
; else
{value}
is
false
When
{variety}
is
union
if
{value}
is
true
for every member of
{member type definitions}
and all members of
{member type definitions}
share a common
ancestor, then
{value}
is
true
else
{value}
is
false
4.2.4 cardinality
[Definition:]
Every
value space
has associated with it the concept of
cardinality
. Some
value space
are finite, some are countably infinite while still others could
conceivably be uncountably infinite (although no
value space
defined by this specification is uncountable infinite). A datatype is
said to have the cardinality of its
value space
It
is sometimes useful to categorize
value space
(and hence, datatypes) as to their cardinality. There are two
significant cases:
value space
s that are finite
value space
s that are countably infinite
cardinality
provides for:
indicating whether the
cardinality
of a
value space
is
finite
or
countably infinite
4.2.4.1 The cardinality Schema Component
Schema Component
cardinality
{value}
One of
{finite, countably infinite}
{value}
depends on
{variety}
{facets}
and
{member type definitions}
in the
Simple Type Definition
component in which a
cardinality
component appears as a member of
{fundamental facets}
When
{variety}
is
atomic
and
{value}
of
{base type definition}
is
finite
, then
{value}
is
finite
When
{variety}
is
atomic
and
{value}
of
{base type definition}
is
countably infinite
and
either
of the following
conditions are true, then
{value}
is
finite
; else
{value}
is
countably infinite
one of
length
maxLength
totalDigits
is among
{facets}
all
of the following are true:
one of
minInclusive
or
minExclusive
is among
{facets}
one of
maxInclusive
or
maxExclusive
is among
{facets}
either
of the following are true:
fractionDigits
is among
{facets}
{base type definition}
is one of
date
gYearMonth
gYear
gMonthDay
gDay
or
gMonth
or any type
derived
from them
When
{variety}
is
list
if
length
or both of
minLength
and
maxLength
are among
{facets}
, then
{value}
is
finite
; else
{value}
is
countably infinite
When
{variety}
is
union
if
{value}
is
finite
for every member of
{member type definitions}
, then
{value}
is
finite
else
{value}
is
countably infinite
4.2.5 numeric
[Definition:]
A datatype is said to be
numeric
if its values are conceptually quantities (in some
mathematical number system).
[Definition:]
A datatype whose values
are not
numeric
is said to be
non-numeric
numeric
provides for:
indicating whether a
value space
is
numeric
4.2.5.1 The numeric Schema Component
Schema Component
numeric
{value}
boolean
{value}
depends on
{variety}
{facets}
{base type definition}
and
{member type definitions}
in the
Simple Type Definition
component
in which a
cardinality
component appears as a member of
{fundamental facets}
When
{variety}
is
atomic
{value}
is inherited from
{value}
of
{base type definition}
For all
primitive
types
{value}
is as specified in the table in
Fundamental Facets (§C.1)
When
{variety}
is
list
{value}
is
false
When
{variety}
is
union
if
{value}
is
true
for every member of
{member type definitions}
, then
{value}
is
true
else
{value}
is
false
4.3 Constraining Facets
4.3.1
length
4.3.2
minLength
4.3.3
maxLength
4.3.4
pattern
4.3.5
enumeration
4.3.6
whiteSpace
4.3.7
maxInclusive
4.3.8
maxExclusive
4.3.9
minExclusive
4.3.10
minInclusive
4.3.11
totalDigits
4.3.12
fractionDigits
4.3.1 length
[Definition:]
length
is the number
of
units of length
, where
units of length
varies depending on the type that is being
derived
from.
The value of
length
must
be a
nonNegativeInteger
For
string
and datatypes
derived
from
string
length
is measured in units of
character
s as defined in
[XML 1.0 (Second Edition)]
For
anyURI
length
is measured in units of
characters (as for
string
).
For
hexBinary
and
base64Binary
and datatypes
derived
from them,
length
is measured in octets (8 bits) of binary data.
For datatypes
derived
by
list
length
is measured in number of list items.
Note:
For
string
and datatypes
derived
from
string
length
will not always coincide with "string length" as perceived
by some users or with the number of storage units in some digital representation.
Therefore, care should be taken when specifying a value for
length
and in attempting to infer storage requirements from a given value for
length
length
provides for:
Constraining a
value space
to values with a specific number of
units of length
where
units of length
varies depending on
{base type definition}
Example
The following is the definition of a
user-derived
datatype to represent product codes which must be
exactly 8 characters in length. By fixing the value of the
length
facet we ensure that types derived from productCode can
change or set the values of other facets, such as
pattern
, but
cannot change the length.
4.3.1.1 The length Schema Component
Schema Component
length
{value}
nonNegativeInteger
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
length
other than
{value}
4.3.1.2 XML Representation of length Schema Components
The XML representation for a
length
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
length
Element Information Item
boolean
: false
id =
ID
value
nonNegativeInteger
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
length
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.1.3 length Validation Rules
Validation Rule: Length Valid
A value in a
value space
is facet-valid with
respect to
length
, determined as follows:
if the
{variety}
is
atomic
then
1.1
if
{primitive type definition}
is
string
or
anyURI
, then the
length of the value, as measured in
character
must
be equal to
{value}
1.2
if
{primitive type definition}
is
hexBinary
or
base64Binary
, then the
length of the value, as measured in octets of the binary data,
must
be equal to
{value}
1.3
if
{primitive type definition}
is
QName
or
NOTATION
, then
any
{value}
is facet-valid.
if the
{variety}
is
list
then the length of the value, as measured
in list items,
must
be equal to
{value}
The use of
length
on datatypes
derived
from
QName
and
NOTATION
is deprecated. Future versions of this
specification may remove this facet for these datatypes.
4.3.1.4 Constraints on length Schema Components
Schema Component Constraint: length and minLength or maxLength
If
length
is a member of
{facets}
then
1 It is an error for
minLength
to be a member of
{facets}
unless
1.1 the
{value}
of
minLength
<= the
{value}
of
length
and
1.2 there is type definition from which this one is derived by
one or more restriction steps in which
minLength
has the same
{value}
and
length
is not specified.
2 It is an error for
maxLength
to be a member of
{facets}
unless
2.1 the
{value}
of
length
<= the
{value}
of
maxLength
and
2.2 there is type definition from which this one is derived by
one or more restriction steps in which
maxLength
has the same
{value}
and
length
is not specified.
Schema Component Constraint: length valid restriction
It is an
error
if
length
is among the members of
{facets}
of
{base type definition}
and
{value}
is
not equal to the
{value}
of the parent
length
4.3.2 minLength
[Definition:]
minLength
is
the minimum number of
units of length
, where
units of length
varies depending on the type that is being
derived
from.
The value of
minLength
must
be a
nonNegativeInteger
For
string
and datatypes
derived
from
string
minLength
is measured in units of
character
s as defined in
[XML 1.0 (Second Edition)]
For
hexBinary
and
base64Binary
and datatypes
derived
from them,
minLength
is measured in octets (8 bits) of binary data.
For datatypes
derived
by
list
minLength
is measured in number of list items.
Note:
For
string
and datatypes
derived
from
string
minLength
will not always coincide with "string length" as perceived
by some users or with the number of storage units in some digital representation.
Therefore, care should be taken when specifying a value for
minLength
and in attempting to infer storage requirements from a given value for
minLength
minLength
provides for:
Constraining a
value space
to values with at least a specific number of
units of length
where
units of length
varies depending on
{base type definition}
Example
The following is the definition of a
user-derived
datatype which requires strings to have at least one character (i.e.,
the empty string is not in the
value space
of this datatype).
4.3.2.1 The minLength Schema Component
Schema Component
minLength
{value}
nonNegativeInteger
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
minLength
other than
{value}
4.3.2.2 XML Representation of minLength Schema Component
The XML representation for a
minLength
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
minLength
Element Information Item
boolean
: false
id =
ID
value
nonNegativeInteger
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
minLength
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.2.3 minLength Validation Rules
Validation Rule: minLength Valid
A value in a
value space
is facet-valid with
respect to
minLength
, determined as follows:
if the
{variety}
is
atomic
then
1.1
if
{primitive type definition}
is
string
or
anyURI
, then the
length of the value, as measured in
character
must
be greater than or equal to
{value}
1.2
if
{primitive type definition}
is
hexBinary
or
base64Binary
, then the
length of the value, as measured in octets of the binary data,
must
be greater than or equal to
{value}
1.3
if
{primitive type definition}
is
QName
or
NOTATION
, then
any
{value}
is facet-valid.
if the
{variety}
is
list
then the length of the value, as measured
in list items,
must
be greater than or equal
to
{value}
The use of
minLength
on datatypes
derived
from
QName
and
NOTATION
is deprecated. Future versions of this
specification may remove this facet for these datatypes.
4.3.2.4 Constraints on minLength Schema Components
Schema Component Constraint: minLength <= maxLength
If both
minLength
and
maxLength
are members of
{facets}
, then the
{value}
of
minLength
must
be less than or equal to the
{value}
of
maxLength
Schema Component Constraint: minLength valid restriction
It is an
error
if
minLength
is among the members of
{facets}
of
{base type definition}
and
{value}
is
less than the
{value}
of the parent
minLength
4.3.3 maxLength
[Definition:]
maxLength
is
the maximum number of
units of length
, where
units of length
varies
depending on the type that is being
derived
from.
The value of
maxLength
must
be a
nonNegativeInteger
For
string
and datatypes
derived
from
string
maxLength
is measured in units of
character
s as defined in
[XML 1.0 (Second Edition)]
For
hexBinary
and
base64Binary
and datatypes
derived
from them,
maxLength
is measured in octets (8 bits) of binary data.
For datatypes
derived
by
list
maxLength
is measured in number of list items.
Note:
For
string
and datatypes
derived
from
string
maxLength
will not always coincide with "string length" as perceived
by some users or with the number of storage units in some digital representation.
Therefore, care should be taken when specifying a value for
maxLength
and in attempting to infer storage requirements from a given value for
maxLength
maxLength
provides for:
Constraining a
value space
to values with at most a specific number of
units of length
where
units of length
varies depending on
{base type definition}
Example
The following is the definition of a
user-derived
datatype which might be used to accept form input with an upper limit
to the number of characters that are acceptable.
4.3.3.1 The maxLength Schema Component
Schema Component
maxLength
{value}
nonNegativeInteger
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
maxLength
other than
{value}
4.3.3.2 XML Representation of maxLength Schema Components
The XML representation for a
maxLength
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
maxLength
Element Information Item
boolean
: false
id =
ID
value
nonNegativeInteger
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
maxLength
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.3.3 maxLength Validation Rules
Validation Rule: maxLength Valid
A value in a
value space
is facet-valid with
respect to
maxLength
, determined as follows:
if the
{variety}
is
atomic
then
1.1
if
{primitive type definition}
is
string
or
anyURI
, then the
length of the value, as measured in
character
must
be less than or equal to
{value}
1.2
if
{primitive type definition}
is
hexBinary
or
base64Binary
, then the
length of the value, as measured in octets of the binary data,
must
be less than or equal to
{value}
1.3
if
{primitive type definition}
is
QName
or
NOTATION
, then
any
{value}
is facet-valid.
if the
{variety}
is
list
then the length of the value, as measured
in list items,
must
be less than or equal to
{value}
The use of
maxLength
on datatypes
derived
from
QName
and
NOTATION
is deprecated. Future versions of this
specification may remove this facet for these datatypes.
4.3.3.4 Constraints on maxLength Schema Components
Schema Component Constraint: maxLength valid restriction
It is an
error
if
maxLength
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater than the
{value}
of the parent
maxLength
4.3.4 pattern
[Definition:]
pattern
is a constraint on the
value space
of a datatype which is achieved by
constraining the
lexical space
to literals
which match a specific pattern. The value of
pattern
must
be a
regular expression
pattern
provides for:
Constraining a
value space
to values that are denoted by literals which match a specific
regular expression
Example
The following is the definition of a
user-derived
datatype which is a better representation of postal codes in the
United States, by limiting strings to those which are matched by
a specific
regular expression
4.3.4.1 The pattern Schema Component
Schema Component
pattern
{value}
regular expression
{annotation}
Optional. An
annotation
4.3.4.2 XML Representation of pattern Schema Components
The XML representation for a
pattern
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
pattern
Element Information Item
ID
value
string
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
{value}
must
be a valid
regular expression
pattern
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.4.3 Constraints on XML Representation of pattern
Schema Representation Constraint: Multiple patterns
If multiple
element information items appear as
[children]
of a
, the
[value]
s should
be combined as if they appeared in a single
regular expression
as separate
branch
es.
Note:
It is a consequence of the schema representation constraint
Multiple patterns (§4.3.4.3)
and of the rules for
restriction
that
pattern
facets specified on the
same
step in a type
derivation are
OR
ed together, while
pattern
facets specified on
different
steps of a type derivation
are
AND
ed together.
Thus, to impose two
pattern
constraints simultaneously,
schema authors may either write a single
pattern
which
expresses the intersection of the two
pattern
s they wish to
impose, or define each
pattern
on a separate type derivation
step.
4.3.4.4 pattern Validation Rules
Validation Rule: pattern valid
A literal in a
lexical space
is facet-valid with
respect to
pattern
if:
the literal is among the set of character sequences denoted by
the
regular expression
specified in
{value}
4.3.5 enumeration
[Definition:]
enumeration
constrains the
value space
to a specified set of values.
enumeration
does not impose an order relation on the
value space
it creates; the value of the
ordered
property of the
derived
datatype remains that of the datatype from which it is
derived
enumeration
provides for:
Constraining a
value space
to a specified set of values.
Example
The following example is a datatype definition for a
user-derived
datatype which limits the values
of dates to the three US holidays enumerated. This datatype
definition would appear in a schema authored by an "end-user" and
shows how to define a datatype by enumerating the values in its
value space
. The enumerated values must be
type-valid literals for the
base type
4.3.5.1 The enumeration Schema Component
Schema Component
enumeration
{value}
A set of values from the
value space
of the
{base type definition}
{annotation}
Optional. An
annotation
4.3.5.2 XML Representation of enumeration Schema Components
The XML representation for an
enumeration
schema
component is an
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
enumeration
Element Information Item
ID
value
anySimpleType
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
{value}
must
be
in the
value space
of
{base type definition}
enumeration
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.5.3 Constraints on XML Representation of enumeration
Schema Representation Constraint: Multiple enumerations
If multiple
element information items appear
as
[children]
of a
the
{value}
of the
enumeration
component should be the set of all such
[value]
s.
4.3.5.4 enumeration Validation Rules
Validation Rule: enumeration valid
A value in a
value space
is facet-valid with
respect to
enumeration
if
the value is one of the values specified in
{value}
4.3.5.5 Constraints on enumeration Schema Components
Schema Component Constraint: enumeration valid restriction
It is an
error
if any member of
{value}
is not in the
value space
of
{base type definition}
4.3.6 whiteSpace
[Definition:]
whiteSpace
constrains the
value space
of types
derived
from
string
such that
the various behaviors
specified in
Attribute Value Normalization
in
[XML 1.0 (Second Edition)]
are realized. The value of
whiteSpace
must be one of {preserve, replace, collapse}.
preserve
No normalization is done, the value is not changed (this is the
behavior required by
[XML 1.0 (Second Edition)]
for element content)
replace
All occurrences of #x9 (tab), #xA (line feed) and #xD (carriage return)
are replaced with #x20 (space)
collapse
After the processing implied by
replace
, contiguous
sequences of #x20's are collapsed to a single #x20, and leading and
trailing #x20's are removed.
Note:
The notation #xA used here (and elsewhere in this specification) represents
the Universal Character Set (UCS) code point
hexadecimal A
(line feed), which is denoted by
U+000A. This notation is to be distinguished from
which is the XML
character reference
to that same UCS code point.
whiteSpace
is applicable to all
atomic
and
list
datatypes. For all
atomic
datatypes other than
string
(and types
derived
by
restriction
from it) the value of
whiteSpace
is
collapse
and cannot be changed by a schema author; for
string
the value of
whiteSpace
is
preserve
; for any type
derived
by
restriction
from
string
the value of
whiteSpace
can
be any of the three legal values. For all datatypes
derived
by
list
the
value of
whiteSpace
is
collapse
and cannot
be changed by a schema author. For all datatypes
derived
by
union
whiteSpace
does not apply directly; however, the
normalization behavior of
union
types is controlled by
the value of
whiteSpace
on that one of the
memberTypes
against which the
union
is successfully validated.
Note:
For more information on
whiteSpace
, see the
discussion on white space normalization in
Schema Component Details
in
[XML Schema Part 1: Structures]
whiteSpace
provides for:
Constraining a
value space
according to
the white space normalization rules.
Example
The following example is the datatype definition for
the
token
built-in
derived
datatype.
4.3.6.1 The whiteSpace Schema Component
Schema Component
whiteSpace
{value}
One of
{preserve, replace, collapse}
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
whiteSpace
other than
{value}
4.3.6.2 XML Representation of whiteSpace Schema Components
The XML representation for a
whiteSpace
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
whiteSpace
Element Information Item
boolean
: false
id =
ID
value
= (
collapse
preserve
replace
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
whiteSpace
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.6.3 whiteSpace Validation Rules
Note:
There are no
Validation Rule
s associated
whiteSpace
For more information, see the
discussion on white space normalization in
Schema Component Details
in
[XML Schema Part 1: Structures]
4.3.6.4 Constraints on whiteSpace Schema Components
Schema Component Constraint: whiteSpace valid restriction
It is an
error
if
whiteSpace
is among the members of
{facets}
of
{base type definition}
and any of the following conditions is
true:
{value}
is
replace
or
preserve
and the
{value}
of the parent
whiteSpace
is
collapse
{value}
is
preserve
and the
{value}
of the parent
whiteSpace
is
replace
4.3.7 maxInclusive
[Definition:]
maxInclusive
is the
inclusive upper bound
of the
value space
for a datatype with the
ordered
property. The value of
maxInclusive
must
be
in the
value space
of the
base type
maxInclusive
provides for:
Constraining a
value space
to values
with a specific
inclusive upper bound
Example
The following is the definition of a
user-derived
datatype which limits values to integers less than or equal to
100, using
maxInclusive
4.3.7.1 The maxInclusive Schema Component
Schema Component
maxInclusive
{value}
A value from the
value space
of the
{base type definition}
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
maxInclusive
other than
{value}
4.3.7.2 XML Representation of maxInclusive Schema Components
The XML representation for a
maxInclusive
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
maxInclusive
Element Information Item
boolean
: false
id =
ID
value
anySimpleType
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
{value}
must
be
in the
value space
of
{base type definition}
maxInclusive
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.7.3 maxInclusive Validation Rules
Validation Rule: maxInclusive Valid
A value in an
ordered
value space
is facet-valid with respect to
maxInclusive
, determined as
follows:
if the
numeric
property in
{fundamental facets}
is
true
, then the value
must
be numerically less than or
equal to
{value}
if the
numeric
property in
{fundamental facets}
is
false
(i.e.,
{base type definition}
is one of the date and time related
datatypes), then the value
must
be chronologically
less than or equal to
{value}
4.3.7.4 Constraints on maxInclusive Schema Components
Schema Component Constraint: minInclusive <= maxInclusive
It is an
error
for the value specified for
minInclusive
to be greater than the value
specified for
maxInclusive
for the same datatype.
Schema Component Constraint: maxInclusive valid restriction
It is an
error
if any of the following conditions
is true:
maxInclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater than the
{value}
of the parent
maxInclusive
maxExclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater than or equal to the
{value}
of the parent
maxExclusive
minInclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
less than the
{value}
of the parent
minInclusive
minExclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
less than or equal to the
{value}
of the parent
minExclusive
4.3.8 maxExclusive
[Definition:]
maxExclusive
is the
exclusive upper bound
of the
value space
for a datatype with the
ordered
property. The value of
maxExclusive
must
be in the
value space
of the
base type
or be equal to
{value}
in
{base type definition}
maxExclusive
provides for:
Constraining a
value space
to values
with a specific
exclusive upper bound
Example
The following is the definition of a
user-derived
datatype which limits values to integers less than or equal to
100, using
maxExclusive
Note that the
value space
of this datatype is identical to
the previous one (named 'one-hundred-or-less').
4.3.8.1 The maxExclusive Schema Component
Schema Component
maxExclusive
{value}
A value from the
value space
of the
{base type definition}
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
maxExclusive
other than
{value}
4.3.8.2 XML Representation of maxExclusive Schema Components
The XML representation for a
maxExclusive
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
maxExclusive
Element Information Item
boolean
: false
id =
ID
value
anySimpleType
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
{value}
must
be
in the
value space
of
{base type definition}
maxExclusive
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.8.3 maxExclusive Validation Rules
Validation Rule: maxExclusive Valid
A value in an
ordered
value space
is facet-valid with respect to
maxExclusive
, determined
as follows:
if the
numeric
property in
{fundamental facets}
is
true
, then the
value
must
be numerically less than
{value}
if the
numeric
property in
{fundamental facets}
is
false
(i.e.,
{base type definition}
is one of the date and time related
datatypes), then the value
must
be chronologically
less than
{value}
4.3.8.4 Constraints on maxExclusive Schema Components
Schema Component Constraint: maxInclusive and maxExclusive
It is an
error
for both
maxInclusive
and
maxExclusive
to be specified in the same derivation step of a datatype definition.
Schema Component Constraint: minExclusive <= maxExclusive
It is an
error
for the value specified for
minExclusive
to be greater than the value
specified for
maxExclusive
for the same datatype.
Schema Component Constraint: maxExclusive valid restriction
It is an
error
if any of the following conditions
is true:
maxExclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater than the
{value}
of the parent
maxExclusive
maxInclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater than the
{value}
of the parent
maxInclusive
minInclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
less than or equal to the
{value}
of the parent
minInclusive
minExclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
less than or equal to the
{value}
of the parent
minExclusive
4.3.9 minExclusive
[Definition:]
minExclusive
is the
exclusive lower bound
of the
value space
for a datatype with the
ordered
property.
The value of
minExclusive
must
be in the
value space
of the
base type
or be equal to
{value}
in
{base type definition}
minExclusive
provides for:
Constraining a
value space
to values
with a specific
exclusive lower bound
Example
The following is the definition of a
user-derived
datatype which limits values to integers greater than or equal to
100, using
minExclusive
Note that the
value space
of this datatype is identical to
the previous one (named 'one-hundred-or-more').
4.3.9.1 The minExclusive Schema Component
Schema Component
minExclusive
{value}
A value from the
value space
of the
{base type definition}
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
minExclusive
other than
{value}
4.3.9.2 XML Representation of minExclusive Schema Components
The XML representation for a
minExclusive
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
minExclusive
Element Information Item
boolean
: false
id =
ID
value
anySimpleType
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
{value}
must
be
in the
value space
of
{base type definition}
minExclusive
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.9.3 minExclusive Validation Rules
Validation Rule: minExclusive Valid
A value in an
ordered
value space
is facet-valid with respect to
minExclusive
if:
if the
numeric
property in
{fundamental facets}
is
true
, then the
value
must
be numerically greater than
{value}
if the
numeric
property in
{fundamental facets}
is
false
(i.e.,
{base type definition}
is one of the date and time related
datatypes), then the value
must
be chronologically
greater than
{value}
4.3.9.4 Constraints on minExclusive Schema Components
Schema Component Constraint: minInclusive and minExclusive
It is an
error
for both
minInclusive
and
minExclusive
to be specified for the same datatype.
Schema Component Constraint: minExclusive < maxInclusive
It is an
error
for the value specified for
minExclusive
to be greater than or equal to the value
specified for
maxInclusive
for the same datatype.
Schema Component Constraint: minExclusive valid restriction
It is an
error
if any of the following conditions
is true:
minExclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
less than the
{value}
of the parent
minExclusive
maxInclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater the
{value}
of the parent
maxInclusive
minInclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
less than the
{value}
of the parent
minInclusive
maxExclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater than or equal to the
{value}
of the parent
maxExclusive
4.3.10 minInclusive
[Definition:]
minInclusive
is the
inclusive lower bound
of the
value space
for a datatype with the
ordered
property. The value of
minInclusive
must
be in the
value space
of the
base type
minInclusive
provides for:
Constraining a
value space
to values
with a specific
inclusive lower bound
Example
The following is the definition of a
user-derived
datatype which limits values to integers greater than or equal to
100, using
minInclusive
4.3.10.1 The minInclusive Schema Component
Schema Component
minInclusive
{value}
A value from the
value space
of the
{base type definition}
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
minInclusive
other than
{value}
4.3.10.2 XML Representation of minInclusive Schema Components
The XML representation for a
minInclusive
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
minInclusive
Element Information Item
boolean
: false
id =
ID
value
anySimpleType
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
{value}
must
be
in the
value space
of
{base type definition}
minInclusive
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.10.3 minInclusive Validation Rules
Validation Rule: minInclusive Valid
A value in an
ordered
value space
is facet-valid with respect to
minInclusive
if:
if the
numeric
property in
{fundamental facets}
is
true
, then the
value
must
be numerically greater than or equal to
{value}
if the
numeric
property in
{fundamental facets}
is
false
(i.e.,
{base type definition}
is one of the date and time related
datatypes), then the value
must
be chronologically
greater than or equal to
{value}
4.3.10.4 Constraints on minInclusive Schema Components
Schema Component Constraint: minInclusive < maxExclusive
It is an
error
for the value specified for
minInclusive
to be greater than or equal to the value
specified for
maxExclusive
for the same datatype.
Schema Component Constraint: minInclusive valid restriction
It is an
error
if any of the following conditions
is true:
minInclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
less than the
{value}
of the parent
minInclusive
maxInclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater the
{value}
of the parent
maxInclusive
minExclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
less than or equal to the
{value}
of the parent
minExclusive
maxExclusive
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater than or equal to the
{value}
of the parent
maxExclusive
4.3.11 totalDigits
[Definition:]
totalDigits
controls the maximum number of values in
the
value space
of datatypes
derived
from
decimal
by restricting it to numbers that are expressible as
i × 10^-n
where
and
are integers such that
|i| < 10^totalDigits
and
0 <= n <= totalDigits
The value of
totalDigits
must
be a
positiveInteger
The term
totalDigits
is chosen to reflect the fact that it
restricts the
value space
to those values that can
be represented lexically using at most
totalDigits
digits. Note that it does not restrict the
lexical space
directly; a lexical representation that adds
additional leading zero digits or trailing fractional zero digits is
still permitted.
4.3.11.1 The totalDigits Schema Component
Schema Component
totalDigits
{value}
positiveInteger
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
totalDigits
other than
{value}
4.3.11.2 XML Representation of totalDigits Schema Components
The XML representation for a
totalDigits
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
totalDigits
Element Information Item
boolean
: false
id =
ID
value
positiveInteger
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
totalDigits
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.11.3 totalDigits Validation Rules
Validation Rule: totalDigits Valid
A value in a
value space
is facet-valid with
respect to
totalDigits
if:
that value is expressible as
i × 10^-n
where
and
are integers such that
|i| < 10^
{value}
and
0 <= n <=
{value}
4.3.11.4 Constraints on totalDigits Schema Components
Schema Component Constraint: totalDigits valid restriction
It is an
error
if
totalDigits
is among the members of
{facets}
of
{base type definition}
and
{value}
is
greater than the
{value}
of the parent
totalDigits
4.3.12 fractionDigits
[Definition:]
fractionDigits
controls the size of the minimum difference
between values
in the
value space
of datatypes
derived
from
decimal
by restricting the
value space
to numbers that are
expressible as
i × 10^-n
where
and
are integers and
0 <= n <= fractionDigits
The value of
fractionDigits
must
be a
nonNegativeInteger
The term
fractionDigits
is chosen to reflect the fact that it
restricts the
value space
to those values that can be
represented lexically using at most
fractionDigits
to the right of the decimal point. Note that it does not restrict the
lexical space
directly; a
non-
canonical lexical representation
that adds additional
leading zero digits or trailing fractional zero digits is still permitted.
Example
The following is the definition of a
user-derived
datatype which could be used to represent the magnitude
of a person's body temperature on the Celsius scale.
This definition would appear in a schema authored by an "end-user"
and shows how to define a datatype by specifying facet values which
constrain the range of the
base type
4.3.12.1 The fractionDigits Schema Component
Schema Component
fractionDigits
{value}
nonNegativeInteger
{fixed}
boolean
{annotation}
Optional. An
annotation
If
{fixed}
is
true
, then types for which
the current type is the
{base type definition}
cannot specify a
value for
fractionDigits
other than
{value}
4.3.12.2 XML Representation of fractionDigits Schema Components
The XML representation for a
fractionDigits
schema
component is a
element information item. The
correspondences between the properties of the information item and
properties of the component are as follows:
XML Representation Summary
fractionDigits
Element Information Item
boolean
: false
id =
ID
value
nonNegativeInteger
{any attributes with non-schema namespace . . .}
Content:
annotation
?)
fractionDigits
Schema Component
Property
Representation
{value}
The
actual value
of the
value
[attribute]
{fixed}
The
actual value
of the
fixed
[attribute]
, if present, otherwise false
{annotation}
The annotations corresponding to all the
element information items in the
[children]
, if any.
4.3.12.3 fractionDigits Validation Rules
Validation Rule: fractionDigits Valid
A value in a
value space
is facet-valid with
respect to
fractionDigits
if:
that value is expressible as
i × 10^-n
where
and
are integers and
0 <= n <=
{value}
4.3.12.4 Constraints on fractionDigits Schema Components
Schema Component Constraint: fractionDigits less than or equal to totalDigits
It is an
error
for
fractionDigits
to
be greater than
totalDigits
Schema Component Constraint: fractionDigits valid restriction
It is an
error
if
fractionDigits
is among the members of
{facets}
of
{base type definition}
and
{value}
is greater than the
{value}
of the parent
fractionDigits
5 Conformance
This specification describes two levels of conformance for
datatype processors. The first is
required of all processors. Support for the other will depend on the
application environments for which the processor is intended.
[Definition:]
Minimally conforming
processors
must
completely and correctly implement the
Constraint on Schemas
and
Validation Rule
[Definition:]
Processors which accept schemas in the form of XML documents as described
in
XML Representation of Simple Type Definition Schema Components (§4.1.2)
(and other relevant portions of
Datatype components (§4)
) are additionally said to provide
conformance to the XML Representation of Schemas
and
must
, when processing schema documents, completely and
correctly implement all
Schema Representation Constraint
in this specification, and
must
adhere exactly to the
specifications in
XML Representation of Simple Type Definition Schema Components (§4.1.2)
(and other relevant portions of
Datatype components (§4)
) for mapping
the contents of such
documents to
schema components
for use in validation.
Note:
By separating the conformance requirements relating to the concrete
syntax of XML schema documents, this specification admits processors
which validate using schemas stored in optimized binary representations,
dynamically created schemas represented as programming language data
structures, or implementations in which particular schemas are compiled
into executable code such as C or Java. Such processors can be said to
be
minimally conforming
but not necessarily in
conformance to
the XML Representation of Schemas
A Schema for Datatype Definitions (normative)
name NMTOKEN #REQUIRED>
name NMTOKEN #REQUIRED
value CDATA #REQUIRED>
]>
elementFormDefault="qualified" xml:lang="en"
targetNamespace="http://www.w3.org/2001/XMLSchema"
version="Id: datatypes.xsd,v 1.4 2004/05/29 10:26:33 ht Exp ">
The schema corresponding to this document is normative,
with respect to the syntactic constraints it expresses in the
XML Schema language. The documentation (within <documentation>
elements) below, is not normative, but rather highlights important
aspects of the W3C Recommendation of which this is a part
First the built-in primitive datatypes. These definitions are for
information only, the real built-in definitions are magic.
For each built-in datatype in this schema (both primitive and
derived) can be uniquely addressed via a URI constructed
as follows:
1) the base URI is the URI of the XML Schema namespace
2) the fragment identifier is the name of the datatype
For example, to address the int datatype, the URI is:
Additionally, each facet definition element can be uniquely
addressed via a URI constructed as follows:
1) the base URI is the URI of the XML Schema namespace
2) the fragment identifier is the name of the facet
For example, to address the maxInclusive facet, the URI is:
Additionally, each facet usage in a built-in datatype definition
can be uniquely addressed via a URI constructed as follows:
1) the base URI is the URI of the XML Schema namespace
2) the fragment identifier is the name of the datatype, followed
by a period (".") followed by the name of the facet
For example, to address the usage of the maxInclusive facet in
the definition of int, the URI is:
NOTATION cannot be used directly in a schema; rather a type
must be derived from it by specifying at least one enumeration
facet whose value is the name of a NOTATION declared in the
schema.
Now the derived primitive types
pattern specifies the content of section 2.12 of XML 1.0e2
and RFC 3066 (Revised version of RFC 1766).
pattern matches production 7 from the XML spec
pattern matches production 5 from the XML spec
pattern matches production 4 from the Namespaces in XML spec
A utility type, not for public use
#all or (possibly empty) subset of {restriction, union, list}
A utility type, not for public use
Can be restricted to required or forbidden
Required at the top level
Forbidden when nested
We should use a substitution group for facets, but
that's ruled out because it would allow users to
add their own, which we're not ready for yet.
base attribute and simpleType child are mutually
exclusive, but one or other is required
itemType attribute and simpleType child are mutually
exclusive, but one or other is required
memberTypes attribute must be non-empty or there must be
at least one simpleType child
B DTD for Datatype Definitions (non-normative)
"%pattern; | %enumeration; | %whiteSpace; | %length; |
%maxLength; | %minLength;">
"value CDATA #REQUIRED
id ID #IMPLIED">
((%annotation;)?, (%restriction; | %list; | %union;))>
name %NCName; #IMPLIED
final %simpleDerivationSet; #IMPLIED
id ID #IMPLIED
%simpleTypeAttrs;>
(%restriction1; |
((%simpleType;)?,(%facet;)*)),
(%attrDecls;))>
base %QName; #IMPLIED
id ID #IMPLIED
%restrictionAttrs;>
itemType %QName; #IMPLIED
id ID #IMPLIED
%listAttrs;>
id ID #IMPLIED
memberTypes %QNames; #IMPLIED
%unionAttrs;>
%facetAttr;
%fixedAttr;
%maxExclusiveAttrs;>
%facetAttr;
%fixedAttr;
%minExclusiveAttrs;>
%facetAttr;
%fixedAttr;
%maxInclusiveAttrs;>
%facetAttr;
%fixedAttr;
%minInclusiveAttrs;>
%facetAttr;
%fixedAttr;
%totalDigitsAttrs;>
%facetAttr;
%fixedAttr;
%fractionDigitsAttrs;>
%facetAttr;
%fixedAttr;
%lengthAttrs;>
%facetAttr;
%fixedAttr;
%minLengthAttrs;>
%facetAttr;
%fixedAttr;
%maxLengthAttrs;>
%facetAttr;
%enumerationAttrs;>
%facetAttr;
%fixedAttr;
%whiteSpaceAttrs;>
%facetAttr;
%patternAttrs;>
C Datatypes and Facets
C.1 Fundamental Facets
The following table shows the values of the fundamental facets
for each
built-in
datatype.
Datatype
ordered
bounded
cardinality
numeric
primitive
string
false
false
countably infinite
false
boolean
false
false
finite
false
float
partial
true
finite
true
double
partial
true
finite
true
decimal
total
false
countably infinite
true
duration
partial
false
countably infinite
false
dateTime
partial
false
countably infinite
false
time
partial
false
countably infinite
false
date
partial
false
countably infinite
false
gYearMonth
partial
false
countably infinite
false
gYear
partial
false
countably infinite
false
gMonthDay
partial
false
countably infinite
false
gDay
partial
false
countably infinite
false
gMonth
partial
false
countably infinite
false
hexBinary
false
false
countably infinite
false
base64Binary
false
false
countably infinite
false
anyURI
false
false
countably infinite
false
QName
false
false
countably infinite
false
NOTATION
false
false
countably infinite
false
derived
normalizedString
false
false
countably infinite
false
token
false
false
countably infinite
false
language
false
false
countably infinite
false
IDREFS
false
false
countably infinite
false
ENTITIES
false
false
countably infinite
false
NMTOKEN
false
false
countably infinite
false
NMTOKENS
false
false
countably infinite
false
Name
false
false
countably infinite
false
NCName
false
false
countably infinite
false
ID
false
false
countably infinite
false
IDREF
false
false
countably infinite
false
ENTITY
false
false
countably infinite
false
integer
total
false
countably infinite
true
nonPositiveInteger
total
false
countably infinite
true
negativeInteger
total
false
countably infinite
true
long
total
true
finite
true
int
total
true
finite
true
short
total
true
finite
true
byte
total
true
finite
true
nonNegativeInteger
total
false
countably infinite
true
unsignedLong
total
true
finite
true
unsignedInt
total
true
finite
true
unsignedShort
total
true
finite
true
unsignedByte
total
true
finite
true
positiveInteger
total
false
countably infinite
true
D ISO 8601 Date and Time Formats
D.1 ISO 8601 Conventions
The
primitive
datatypes
duration
dateTime
time
date
gYearMonth
gMonthDay
gDay
gMonth
and
gYear
use lexical formats inspired by
[ISO 8601]
Following
[ISO 8601]
, the lexical forms of
these datatypes can include only the characters #20 through #7F.
This appendix provides more detail on the ISO
formats and discusses some deviations from them for the datatypes
defined in this specification.
[ISO 8601]
"specifies the representation of dates in the
proleptic Gregorian calendar and times and representations of periods of time".
The proleptic Gregorian calendar includes dates prior to 1582 (the year it came
into use as an ecclesiastical calendar).
It should be pointed out that the datatypes described in this
specification do not cover all the types of data covered by
[ISO 8601]
, nor do they support all the lexical
representations for those types of data.
[ISO 8601]
lexical formats are described using "pictures"
in which characters are used in place of decimal digits.
The allowed decimal digits are (#x30-#x39).
For the primitive datatypes
dateTime
time
date
gYearMonth
gMonthDay
gDay
gMonth
and
gYear
these characters have the following meanings:
C -- represents a digit used in the thousands and hundreds components,
the "century" component, of the time element "year". Legal values are
from 0 to 9.
Y -- represents a digit used in the tens and units components of the time
element "year". Legal values are from 0 to 9.
M -- represents a digit used in the time element "month". The two
digits in a MM format can have values from 1 to 12.
D -- represents a digit used in the time element "day". The two digits
in a DD format can have values from 1 to 28 if the month value equals 2,
1 to 29 if the month value equals 2 and the year is a leap year, 1 to 30
if the month value equals 4, 6, 9 or 11, and 1 to 31 if the month value
equals 1, 3, 5, 7, 8, 10 or 12.
h -- represents a digit used in the time element "hour". The two digits
in a hh format can have values from 0 to
24.
If the value of the hour element is 24 then the values of the minutes
element and the seconds element must be 00 and 00.
m -- represents a digit used in the time element "minute". The two digits
in a mm format can have values from 0 to 59.
s -- represents a digit used in the time element "second". The two
digits in a ss format can have values from 0 to 60. In the formats
described in this specification the whole number of seconds
may
be followed by decimal seconds to an arbitrary level of precision.
This is represented in the picture by "ss.sss". A value of 60 or more is
allowed only in the case of leap seconds.
Strictly speaking, a value of
60 or more is not sensible unless the month and day could
represent March 31, June 30, September 30, or December 31
in UTC
Because the leap second is added or subtracted as the last second of the day
in UTC time, the long (or short) minute could occur at other times in local
time. In cases where the leap second is used with an inappropriate month
and day it, and any fractional seconds, should considered as added or
subtracted from the following minute.
For all the information items indicated by the above characters, leading
zeros are required where indicated.
In addition to the above, certain characters are used as designators
and appear as themselves in lexical formats.
T -- is used as time designator to indicate the start of the
representation of the time of day in
dateTime
Z -- is used as time-zone designator, immediately (without a space)
following a data element expressing the time of day in Coordinated
Universal Time (UTC) in
dateTime
time
date
gYearMonth
gMonthDay
gDay
gMonth
, and
gYear
In the lexical format for
duration
the following
characters are also used as designators and appear as themselves in
lexical formats:
P -- is used as the time duration designator, preceding a data element
representing a given duration of time.
Y -- follows the number of years in a time duration.
M -- follows the number of months or minutes in a time duration.
D -- follows the number of days in a time duration.
H -- follows the number of hours in a time duration.
S -- follows the number of seconds in a time duration.
The values of the
Year, Month, Day, Hour and Minutes components are not restricted but
allow an arbitrary integer. Similarly, the value of the Seconds component
allows an arbitrary decimal. Thus, the lexical format for
duration
and datatypes derived from it
does not follow the alternative
format of § 5.5.3.2.1 of
[ISO 8601]
D.2 Truncated and Reduced Formats
[ISO 8601]
supports a variety of "truncated" formats in
which some of the characters on the left of specific formats, for example,
the
century, can be omitted.
Truncated formats are, in
general, not permitted for the datatypes defined in this specification
with three exceptions. The
time
datatype uses
a truncated format for
dateTime
which represents an instant of time that recurs every day.
Similarly, the
gMonthDay
and
gDay
datatypes use left-truncated formats for
date
The datatype
gMonth
uses a right and left truncated format for
date
[ISO 8601]
also supports a variety of "reduced" or right-truncated
formats in which some of the characters to the right of specific formats,
such as the
time specification, can be omitted. Right truncated formats are also, in
general,
not permitted for the datatypes defined in this specification
with the following exceptions:
right-truncated representations of
dateTime
are used as
lexical representations for
date
gMonth
gYear
D.3 Deviations from ISO 8601 Formats
D.3.1
Sign Allowed
D.3.2
No Year Zero
D.3.3
More Than 9999 Years
D.3.4
Time zone permitted
D.3.1 Sign Allowed
An optional minus sign is allowed immediately preceding, without a space,
the lexical representations for
duration
dateTime
date
gYearMonth
gYear
D.3.2 No Year Zero
The year "0000" is an illegal year value.
D.3.3 More Than 9999 Years
To accommodate year values greater than 9999, more than four digits are
allowed in the year representations of
dateTime
date
gYearMonth
, and
gYear
This follows
[ISO 8601:2000 Second Edition]
D.3.4 Time zone permitted
The lexical representations for the datatypes
date
gYearMonth
gMonthDay
gDay
gMonth
and
gYear
permit an optional
trailing time zone specificiation.
E Adding durations to dateTimes
Given a
dateTime
S and a
duration
D, this
appendix specifies how to compute a
dateTime
E where E is the
end of the time period with start S and duration D i.e. E = S + D. Such
computations are used, for example, to determine whether a
dateTime
is within a specific time period. This appendix also addresses the addition of
duration
s to the datatypes
date
gYearMonth
gYear
gDay
and
gMonth
, which can be viewed as a set of
dateTime
s.
In such cases, the addition is made to the first or starting
dateTime
in the set.
This is a logical explanation of the process.
Actual implementations are free to optimize as long as they produce the same
results.
The calculation uses the notation S[year] to represent the year
field of S, S[month] to represent the month field, and so on. It also depends on
the following functions:
fQuotient(a, b) = the greatest integer less than or equal to a/b
fQuotient(-1,3) = -1
fQuotient(0,3)...fQuotient(2,3) = 0
fQuotient(3,3) = 1
fQuotient(3.123,3) = 1
modulo(a, b) = a - fQuotient(a,b)*b
modulo(-1,3) = 2
modulo(0,3)...modulo(2,3) = 0...2
modulo(3,3) = 0
modulo(3.123,3) = 0.123
fQuotient(a, low, high) = fQuotient(a - low, high - low)
fQuotient(0, 1, 13) = -1
fQuotient(1, 1, 13) ... fQuotient(12, 1, 13) = 0
fQuotient(13, 1, 13) = 1
fQuotient(13.123, 1, 13) = 1
modulo(a, low, high) = modulo(a - low, high - low) + low
modulo(0, 1, 13) = 12
modulo(1, 1, 13) ... modulo(12, 1, 13) = 1...12
modulo(13, 1, 13) = 1
modulo(13.123, 1, 13) = 1.123
maximumDayInMonthFor(yearValue, monthValue) =
M := modulo(monthValue, 1, 13)
Y := yearValue + fQuotient(monthValue, 1, 13)
Return a value based on M and Y:
31
M = January, March, May, July, August, October, or
December
30
M = April, June, September, or November
29
M = February AND (modulo(Y, 400) = 0 OR
(modulo(Y, 100) != 0) AND modulo(Y, 4) = 0)
28
Otherwise
E.1 Algorithm
Essentially, this calculation is equivalent to separating D into
and
If the day is out of range, it is
pinned
to be within range. Thus April
31 turns into April 30. Then the
latter addition can cause the year and month to change.
Leap seconds are handled by the computation by treating them as overflows.
Essentially, a value of 60
seconds in S is treated as if it were a duration of 60 seconds added to S
(with a zero seconds field). All calculations
thereafter use 60 seconds per minute.
Thus the addition of either PT1M or PT60S to any dateTime will always
produce the same result. This is a special definition of addition which
is designed to match common practice, and -- most importantly -- be stable
over time.
A definition that attempted to take leap-seconds into account would need to
be constantly updated, and could not predict the results of future
implementation's additions. The decision to introduce a leap second in UTC
is the responsibility of the
[International Earth Rotation Service (IERS)]
. They make periodic
announcements as to when
leap seconds are to be added, but this is not known more than a year in
advance. For more information on leap seconds, see
[U.S. Naval Observatory Time Service Department]
The following is the precise specification. These steps must be followed in
the same order. If a field in D is not specified, it is treated as if it were
zero. If a field in S is not specified, it is treated in the calculation as if
it were the minimum allowed value in that field, however, after the calculation
is concluded, the corresponding field in E is removed (set to unspecified).
Months (may be modified additionally below)
temp := S[month] + D[month]
E[month] := modulo(temp, 1, 13)
carry := fQuotient(temp, 1, 13)
Years (may be modified additionally below)
E[year] := S[year] + D[year] + carry
Zone
E[zone] := S[zone]
Seconds
temp := S[second] + D[second]
E[second] := modulo(temp, 60)
carry := fQuotient(temp, 60)
Minutes
temp := S[minute] + D[minute] + carry
E[minute] := modulo(temp, 60)
carry := fQuotient(temp, 60)
Hours
temp := S[hour] + D[hour] + carry
E[hour] := modulo(temp, 24)
carry := fQuotient(temp, 24)
Days
if S[day] > maximumDayInMonthFor(E[year], E[month])
tempDays := maximumDayInMonthFor(E[year], E[month])
else if S[day] < 1
tempDays := 1
else
tempDays := S[day]
E[day] := tempDays + D[day] + carry
START LOOP
IF
E[day] < 1
E[day] := E[day] + maximumDayInMonthFor(E[year], E[month] - 1)
carry := -1
ELSE IF
E[day] > maximumDayInMonthFor(E[year], E[month])
E[day] := E[day] - maximumDayInMonthFor(E[year], E[month])
carry := 1
ELSE EXIT LOOP
temp := E[month] + carry
E[month] := modulo(temp, 1, 13)
E[year] := E[year] + fQuotient(temp, 1, 13)
GOTO START LOOP
Examples:
dateTime
duration
result
2000-01-12T12:13:14Z
P1Y3M5DT7H10M3.3S
2001-04-17T19:23:17.3Z
2000-01
-P3M
1999-10
2000-01-12
PT33H
2000-01-13
E.2 Commutativity and Associativity
Time durations are added by simply adding each of their fields, respectively,
without overflow.
The order of addition of durations to instants
is
significant.
For example, there are cases where:
((dateTime + duration1) + duration2) != ((dateTime +
duration2) + duration1)
Example:
(2000-03-30 + P1D) + P1M = 2000-03-31 + P1M = 2000-
04-30
(2000-03-30 + P1M) + P1D = 2000-04-30 + P1D = 2000-
05-01
F Regular Expressions
regular expression
is a sequence of
characters that denote a
set of strings
L(R)
When used to constrain a
lexical space
, a
regular expression
asserts that only strings
in
L(R)
are valid literals for values of that type.
Note:
Unlike some popular regular expression languages (including those
defined by Perl and standard Unix utilities), the regular
expression language defined here implicitly anchors all regular
expressions at the head and tail, as the most common use of
regular expressions in
pattern
is to match entire literals.
For example, a datatype
derived
from
string
such
that all values must begin with the character
(#x41) and end with the character
(#x5a) would be defined as follows:
In regular expression languages that are not implicitly anchored at the head and tail,
it is customary to write the equivalent regular expression as:
^A.*Z$
where "^" anchors the pattern at the head and "$" anchors at the tail.
In those rare cases where an unanchored match is desired, including
.*
at the beginning and ending of the regular expression will
achieve the desired results. For example, a datatype
derived
from string such that all values must contain at least 3 consecutive
#x41
) characters somewhere within the value could be defined as follows:
[Definition:]
regular expression
is composed from zero or more
branch
es, separated by
characters.
Regular Expression
[1]
regExp
::=
branch
( '|'
branch
)*
For all
branch
es
, and for all
regular expression
, valid
regular expression
are:
Denoting the set of strings
L(R)
containing:
(empty string)
the set containing just the empty string
all strings in
L(S)
all strings in
L(S)
and
all strings in
L(T)
[Definition:]
branch
consists
of zero or more
piece
s, concatenated together.
Branch
[2]
branch
::=
piece
For all
piece
, and for all
branch
es
, valid
branch
es
are:
Denoting the set of strings
L(R)
containing:
all strings in
L(S)
all strings
st
with
in
L(S)
and
in
L(T)
[Definition:]
piece
is an
atom
, possibly followed by a
quantifier
Piece
[3]
piece
::=
atom
quantifier
For all
atom
and non-negative
integers
such that
n <= m
, valid
piece
are:
Denoting the set of strings
L(R)
containing:
all strings in
L(S)
the empty string, and all strings in
L(S)
All strings in
L(S?)
and all strings
st
with
in
L(S*)
and
in
L(S)
( all concatenations
of zero or more strings from L(S) )
All strings
st
with
in
L(S)
and
in
L(S*)
( all concatenations
of one or more strings from L(S) )
{n,m}
All strings
st
with
in
L(S)
and
in
L(S{n-1,m-1})
( All
sequences of at least n, and at most m, strings from L(S) )
{n}
All strings in
L(S{n,n})
( All
sequences of exactly n strings from L(S) )
{n,}
All strings in L(S{n}S*)
( All
sequences of at least n, strings from L(S) )
{0,m}
All strings
st
with
in
L(S?)
and
in
L(S{0,m-1})
( All
sequences of at most m, strings from L(S) )
{0,0}
The set containing only the empty string
Note:
The regular expression language in the Perl Programming Language
[Perl]
does not include a quantifier of the form
S{,m}
, since it is logically equivalent to
S{0,m}
We have, therefore, left this logical possibility out of the regular
expression language defined by this specification.
[Definition:]
quantifier
is one of
{n,m}
or
{n,}
, which have the meanings
defined in the table above.
Quanitifer
[4]
quantifier
::=
[?*+] | ( '{'
quantity
'}' )
[5]
quantity
::=
quantRange
quantMin
QuantExact
[6]
quantRange
::=
QuantExact
','
QuantExact
[7]
quantMin
::=
QuantExact
','
[8]
QuantExact
::=
[0-9]+
[Definition:]
An
atom
is either a
normal character
, a
character class
, or
a parenthesized
regular expression
Atom
[9]
atom
::=
Char
charClass
| ( '('
regExp
')' )
For all
normal character
character class
es
, and
regular expression
, valid
atom
are:
Denoting the set of strings
L(R)
containing:
the single string consisting only of
all strings in
L(C)
all strings in
L(S)
[Definition:]
metacharacter
is either
or
These characters have special meanings in
regular expression
s,
but can be escaped to form
atom
s that denote the
sets of strings containing only themselves, i.e., an escaped
metacharacter
behaves like a
normal character
[Definition:]
normal character
is any XML character that is not a
metacharacter. In
regular expression
s, a normal character is an
atom that denotes the singleton set of strings containing only itself.
Normal Character
[10]
Char
::=
[^.\?*+()|#x5B#x5D]
Note that a
normal character
can be represented either as
itself, or with a
character
reference
F.1 Character Classes
[Definition:]
character class
is an
atom
that identifies a
set of characters
C(R)
. The set of strings
L(R)
denoted by a
character class
contains one single-character string
" for each character
in
C(R)
Character Class
[11]
charClass
::=
charClassEsc
charClassExpr
WildcardEsc
A character class is either a
character class escape
or a
character class expression
[Definition:]
character class expression
is a
character group
surrounded
by
and
characters. For all character
groups
, [
] is a valid
character class
expression
, identifying the set of characters
([
]) =
).
Character Class Expression
[12]
charClassExpr
::=
'['
charGroup
']'
[Definition:]
character group
is either a
positive character group
negative character group
, or a
character class subtraction
Character Group
[13]
charGroup
::=
posCharGroup
negCharGroup
charClassSub
[Definition:]
positive character group
consists of one or more
character range
s or
character class escape
s, concatenated
together. A
positive character group
identifies the set of
characters containing all of the characters in all of the sets identified
by its constituent ranges or escapes.
Positive Character Group
[14]
posCharGroup
::=
charRange
charClassEsc
)+
For all
character range
, all
character class escape
, and all
positive character group
, valid
positive character group
are:
Identifying the set of characters
C(G)
containing:
all characters in
C(R)
all characters in
C(E)
RP
all characters in
C(R)
and all
characters in
C(P)
EP
all characters in
C(E)
and all
characters in
C(P)
[Definition:]
negative character group
is a
positive character group
preceded by the
character.
For all
positive character group
, ^
is a valid
negative character group
, and
C(^P)
contains all XML characters that are
not
in
C(P)
Negative Character Group
[15]
negCharGroup
::=
'^'
posCharGroup
[Definition:]
character class subtraction
is a
character class expression
subtracted from a
positive character group
or
negative character group
, using the
character.
Character Class Subtraction
[16]
charClassSub
::=
posCharGroup
negCharGroup
) '-'
charClassExpr
For any
positive character group
or
negative character group
, and any
character class expression
G-C
is a valid
character class subtraction
, identifying the set of all characters in
C(G)
that are not also in
C(C)
[Definition:]
character range
identifies a set of
characters
C(R)
containing all XML characters with UCS
code points in a specified range.
Character Range
[17]
charRange
::=
seRange
XmlCharIncDash
[18]
seRange
::=
charOrEsc
'-'
charOrEsc
[20]
charOrEsc
::=
XmlChar
SingleCharEsc
[21]
XmlChar
::=
[^\#x2D#x5B#x5D]
[22]
XmlCharIncDash
::=
[^\#x5B#x5D]
A single XML character is a
character range
that identifies
the set of characters containing only itself. All XML characters are valid
character ranges, except as follows:
The
and
characters are not
valid character ranges;
The
character is only valid at the beginning of a
positive character group
if it is part of a
negative character group
The
character is a valid character range only at the beginning
or end of a
positive character group
Note:
The grammar for
character range
as
given above is ambiguous, but the second and third bullets above
together remove the ambiguity.
character range
may
also be written
in the form
s-e
, identifying the set that contains all XML characters
with UCS code points greater than or equal to the code point
of
, but not greater than the code point of
s-e
is a valid character range iff:
is a
single character escape
, or an XML character;
is not
If s is the first character in a
character class expression
, then
is not
is a
single character escape
, or an XML character;
is not
or
; and
The code point of
is greater than or equal to the code
point of
Note:
The code point of a
single character escape
is the code point of the
single character in the set of characters that it identifies.
F.1.1 Character Class Escapes
[Definition:]
character class escape
is a short sequence of characters
that identifies predefined character class. The valid character
class escapes are the
single character escape
s, the
multi-character escape
s, and the
category escape
s (including
the
block escape
s).
Character Class Escape
[23]
charClassEsc
::=
SingleCharEsc
MultiCharEsc
catEsc
complEsc
[Definition:]
single character escape
identifies a set containing a only
one character -- usually because that character is difficult or
impossible to write directly into a
regular expression
Single Character Escape
[24]
SingleCharEsc
::=
'\' [nrt\|.?*+(){}#x2D#x5B#x5D#x5E]
The valid
single character escape
s are:
Identifying the set of characters
C(R)
containing:
\n
the newline character (#xA)
\r
the return character (#xD)
\t
the tab character (#x9)
\\
\|
\.
\-
\^
\?
\*
\+
\{
\}
\(
\)
\[
\]
[Definition:]
[Unicode Database]
specifies a number of possible
values for the "General Category" property
and provides mappings from code points to specific character properties.
The set containing all characters that have property
can be identified with a
category escape
\p{X}
The complement of this set is specified with the
category escape
\P{X}
[\P{X}]
[^\p{X}]
).
Category Escape
[25]
catEsc
::=
'\p{'
charProp
'}'
[26]
complEsc
::=
'\P{'
charProp
'}'
[27]
charProp
::=
IsCategory
IsBlock
Note:
[Unicode Database]
is subject to future revision. For example, the
mapping from code points to character properties might be updated.
All
minimally conforming
processors
must
support the character properties defined in the version of
[Unicode Database]
that is current at the time this specification became a W3C
Recommendation. However, implementors are encouraged to support the
character properties defined in any future version.
The following table specifies the recognized values of the
"General Category" property.
Category
Property
Meaning
Letters
All Letters
Lu
uppercase
Ll
lowercase
Lt
titlecase
Lm
modifier
Lo
other
Marks
All Marks
Mn
nonspacing
Mc
spacing combining
Me
enclosing
Numbers
All Numbers
Nd
decimal digit
Nl
letter
No
other
Punctuation
All Punctuation
Pc
connector
Pd
dash
Ps
open
Pe
close
Pi
initial quote
(may behave like Ps or Pe depending on usage)
Pf
final quote
(may behave like Ps or Pe depending on usage)
Po
other
Separators
All Separators
Zs
space
Zl
line
Zp
paragraph
Symbols
All Symbols
Sm
math
Sc
currency
Sk
modifier
So
other
Other
All Others
Cc
control
Cf
format
Co
private use
Cn
not assigned
Categories
[28]
IsCategory
::=
Letters
Marks
Numbers
Punctuation
Separators
Symbols
Others
[29]
Letters
::=
'L' [ultmo]?
[30]
Marks
::=
'M' [nce]?
[31]
Numbers
::=
'N' [dlo]?
[32]
Punctuation
::=
'P' [cdseifo]?
[33]
Separators
::=
'Z' [slp]?
[34]
Symbols
::=
'S' [mcko]?
[35]
Others
::=
'C' [cfon]?
Note:
The properties mentioned above exclude the
Cs
property.
The
Cs
property identifies "surrogate" characters, which do not
occur at the level of the "character abstraction" that XML instance documents
operate on.
[Definition:]
[Unicode Database]
groups code points into a number of blocks
such as Basic Latin (i.e., ASCII), Latin-1 Supplement, Hangul Jamo,
CJK Compatibility, etc.
The set containing all characters that have block name
(with all white space stripped out),
can be identified with a
block escape
\p{IsX}
The complement of this set is specified with the
block escape
\P{IsX}
[\P{IsX}]
[^\p{IsX}]
).
Block Escape
[36]
IsBlock
::=
'Is' [a-zA-Z0-9#x2D]+
The following table specifies the recognized block names (for more
information, see the "Blocks.txt" file in
[Unicode Database]
).
Start Code
End Code
Block Name
Start Code
End Code
Block Name
#x0000
#x007F
BasicLatin
#x0080
#x00FF
Latin-1Supplement
#x0100
#x017F
LatinExtended-A
#x0180
#x024F
LatinExtended-B
#x0250
#x02AF
IPAExtensions
#x02B0
#x02FF
SpacingModifierLetters
#x0300
#x036F
CombiningDiacriticalMarks
#x0370
#x03FF
Greek
#x0400
#x04FF
Cyrillic
#x0530
#x058F
Armenian
#x0590
#x05FF
Hebrew
#x0600
#x06FF
Arabic
#x0700
#x074F
Syriac
#x0780
#x07BF
Thaana
#x0900
#x097F
Devanagari
#x0980
#x09FF
Bengali
#x0A00
#x0A7F
Gurmukhi
#x0A80
#x0AFF
Gujarati
#x0B00
#x0B7F
Oriya
#x0B80
#x0BFF
Tamil
#x0C00
#x0C7F
Telugu
#x0C80
#x0CFF
Kannada
#x0D00
#x0D7F
Malayalam
#x0D80
#x0DFF
Sinhala
#x0E00
#x0E7F
Thai
#x0E80
#x0EFF
Lao
#x0F00
#x0FFF
Tibetan
#x1000
#x109F
Myanmar
#x10A0
#x10FF
Georgian
#x1100
#x11FF
HangulJamo
#x1200
#x137F
Ethiopic
#x13A0
#x13FF
Cherokee
#x1400
#x167F
UnifiedCanadianAboriginalSyllabics
#x1680
#x169F
Ogham
#x16A0
#x16FF
Runic
#x1780
#x17FF
Khmer
#x1800
#x18AF
Mongolian
#x1E00
#x1EFF
LatinExtendedAdditional
#x1F00
#x1FFF
GreekExtended
#x2000
#x206F
GeneralPunctuation
#x2070
#x209F
SuperscriptsandSubscripts
#x20A0
#x20CF
CurrencySymbols
#x20D0
#x20FF
CombiningMarksforSymbols
#x2100
#x214F
LetterlikeSymbols
#x2150
#x218F
NumberForms
#x2190
#x21FF
Arrows
#x2200
#x22FF
MathematicalOperators
#x2300
#x23FF
MiscellaneousTechnical
#x2400
#x243F
ControlPictures
#x2440
#x245F
OpticalCharacterRecognition
#x2460
#x24FF
EnclosedAlphanumerics
#x2500
#x257F
BoxDrawing
#x2580
#x259F
BlockElements
#x25A0
#x25FF
GeometricShapes
#x2600
#x26FF
MiscellaneousSymbols
#x2700
#x27BF
Dingbats
#x2800
#x28FF
BraillePatterns
#x2E80
#x2EFF
CJKRadicalsSupplement
#x2F00
#x2FDF
KangxiRadicals
#x2FF0
#x2FFF
IdeographicDescriptionCharacters
#x3000
#x303F
CJKSymbolsandPunctuation
#x3040
#x309F
Hiragana
#x30A0
#x30FF
Katakana
#x3100
#x312F
Bopomofo
#x3130
#x318F
HangulCompatibilityJamo
#x3190
#x319F
Kanbun
#x31A0
#x31BF
BopomofoExtended
#x3200
#x32FF
EnclosedCJKLettersandMonths
#x3300
#x33FF
CJKCompatibility
#x3400
#x4DB5
CJKUnifiedIdeographsExtensionA
#x4E00
#x9FFF
CJKUnifiedIdeographs
#xA000
#xA48F
YiSyllables
#xA490
#xA4CF
YiRadicals
#xAC00
#xD7A3
HangulSyllables
#xE000
#xF8FF
PrivateUse
#xF900
#xFAFF
CJKCompatibilityIdeographs
#xFB00
#xFB4F
AlphabeticPresentationForms
#xFB50
#xFDFF
ArabicPresentationForms-A
#xFE20
#xFE2F
CombiningHalfMarks
#xFE30
#xFE4F
CJKCompatibilityForms
#xFE50
#xFE6F
SmallFormVariants
#xFE70
#xFEFE
ArabicPresentationForms-B
#xFEFF
#xFEFF
Specials
#xFF00
#xFFEF
HalfwidthandFullwidthForms
#xFFF0
#xFFFD
Specials
Note:
The blocks mentioned above exclude the
HighSurrogates
LowSurrogates
and
HighPrivateUseSurrogates
blocks.
These blocks identify "surrogate" characters, which do not
occur at the level of the "character abstraction" that XML instance documents
operate on.
Note:
[Unicode Database]
is subject to future revision.
For example, the
grouping of code points into blocks might be updated.
All
minimally conforming
processors
must
support the blocks defined in the version of
[Unicode Database]
that is current at the time this specification became a W3C
Recommendation. However, implementors are encouraged to support the
blocks defined in any future version of the Unicode Standard.
For example, the
block escape
for identifying the
ASCII characters is
\p{IsBasicLatin}
[Definition:]
multi-character escape
provides a simple way to identify
a commonly used set of characters:
Multi-Character Escape
[37]
MultiCharEsc
::=
'\' [sSiIcCdDwW]
[37a]
WildcardEsc
::=
'.'
Character sequence
Equivalent
character class
[^\n\r]
\s
[#x20\t\n\r]
\S
[^\s]
\i
the set of initial name characters, those
match
ed by
Letter
| '_' | ':'
\I
[^\i]
\c
the set of name characters, those
match
ed by
NameChar
\C
[^\c]
\d
\p{Nd}
\D
[^\d]
\w
[#x0000-#x10FFFF]-[\p{P}\p{Z}\p{C}]
all characters except the set of "punctuation",
"separator" and "other" characters
\W
[^\w]
Note:
The
regular expression
language defined here does not
attempt to provide a general solution to "regular expressions" over
UCS character sequences. In particular, it does not easily provide
for matching sequences of base characters and combining marks.
The language is targeted at support of "Level 1" features as defined in
[Unicode Regular Expression Guidelines]
. It is hoped that future versions of this
specification will provide support for "Level 2" features.
G Glossary (non-normative)
The listing below is for the benefit of readers of a printed version of this
document: it collects together all the definitions which appear in the
document above.
atomic
Atomic
datatypes
are those having values which are regarded by this specification as
being indivisible.
base type
Every
datatype that is
derived
by
restriction
is defined in terms of an existing datatype, referred to as its
base type
base type
s can be either
primitive
or
derived
bounded
A datatype is
bounded
if its
value space
has either an
inclusive upper bound
or an
exclusive upper bound
and either an
inclusive lower bound
or
an
exclusive lower bound
built-in
Built-in
datatypes are those which are defined in this specification,
and can be either
primitive
or
derived
canonical lexical representation
canonical lexical representation
is a set of literals from among the valid set of literals
for a datatype such that there is a one-to-one mapping between literals
in the
canonical lexical representation
and
values in the
value space
cardinality
Every
value space
has associated with it the concept of
cardinality
. Some
value space
are finite, some are countably infinite while still others could
conceivably be uncountably infinite (although no
value space
defined by this specification is uncountable infinite). A datatype is
said to have the cardinality of its
value space
comparable
otherwise they are
comparable
conformance to the XML Representation of Schemas
Processors which accept schemas in the form of XML documents as described
in
XML Representation of Simple Type Definition Schema Components (§4.1.2)
(and other relevant portions of
Datatype components (§4)
) are additionally said to provide
conformance to the XML Representation of Schemas
and
must
, when processing schema documents, completely and
correctly implement all
Schema Representation Constraint
in this specification, and
must
adhere exactly to the
specifications in
XML Representation of Simple Type Definition Schema Components (§4.1.2)
(and other relevant portions of
Datatype components (§4)
) for mapping
the contents of such
documents to
schema components
for use in validation.
constraining facet
constraining facet
is an optional property that can be
applied to a datatype to constrain its
value space
Constraint on Schemas
Constraint on Schemas
datatype
In this specification,
datatype
is a 3-tuple, consisting of
a) a set of distinct values, called its
value space
b) a set of lexical representations, called its
lexical space
, and c) a set of
facet
that characterize properties of the
value space
individual values or lexical items.
derived
Derived
datatypes are those that are defined in terms of other datatypes.
error
error
exclusive lower bound
A value
in an
ordered
value space
is said to be an
exclusive lower bound
of a
value space
(where
is a subset of
if for all
in
exclusive upper bound
A value
in an
ordered
value space
is said to be an
exclusive upper bound
of a
value space
(where
is a subset of
if for all
in
facet
facet
is a single
defining aspect of a
value space
. Generally
speaking, each facet characterizes a
value space
along independent axes or dimensions.
for compatibility
for compatibility
fundamental facet
fundamental facet
is an abstract property which
serves to semantically characterize the values in a
value space
inclusive lower bound
A value
in an
ordered
value space
is said to be an
inclusive lower bound
of a
value space
(where
is a subset of
if for all
in
<=
inclusive upper bound
A value
in an
ordered
value space
is said to be an
inclusive upper bound
of a
value space
(where
is a subset of
if for all
in
>=
incomparable
When
a <> b
and
are
incomparable
itemType
The
atomic
or
union
datatype that participates in the definition of a
list
datatype
is known as the
itemType
of that
list
datatype.
lexical space
lexical space
is the set of valid
literals
for a datatype.
list
List
datatypes are those having values each of which consists of a
finite-length (possibly empty) sequence of values of an
atomic
datatype.
match
match
may
may
memberTypes
The datatypes that participate in the
definition of a
union
datatype are known as the
memberTypes
of that
union
datatype.
minimally conforming
Minimally conforming
processors
must
completely and correctly implement the
Constraint on Schemas
and
Validation Rule
must
must
non-numeric
A datatype whose values
are not
numeric
is said to be
non-numeric
numeric
A datatype is said to be
numeric
if its values are conceptually quantities (in some
mathematical number system).
order-relation
An
order relation
on a
value space
is a mathematical relation that imposes a
total order
or a
partial order
on the
members of the
value space
ordered
value space
, and hence a datatype, is said to be
ordered
if there exists an
order-relation
defined for that
value space
partial order
partial order
is an
order-relation
that is
irreflexive
asymmetric
and
transitive
primitive
Primitive
datatypes are those that are not defined in terms of other datatypes;
they exist
ab initio
regular expression
regular expression
is composed from zero or more
branch
es, separated by
characters.
restriction
A datatype is said to be
derived
by
restriction
from another datatype
when values for zero or more
constraining facet
s are specified
that serve to constrain its
value space
and/or its
lexical space
to a subset of those of its
base type
Schema Representation Constraint
Schema Representation Constraint
total order
total order
is an
partial order
such that for no
and
is it the case that
a <> b
union
Union
datatypes are those whose
value space
s and
lexical space
s are the union of
the
value space
s and
lexical space
s of one or more other datatypes.
user-derived
User-derived
datatypes are those
derived
datatypes that are defined by individual schema designers.
Validation Rule
Validation Rule
value space
value
space
is the set of values for a given datatype.
Each value in the
value space
of a datatype is denoted by
one or more literals in its
lexical space
H References
H.1 Normative
Clinger, WD (1990)
William D Clinger.
How to Read Floating Point Numbers Accurately.
In
Proceedings of Conference on Programming Language Design and
Implementation
, pages 92-101.
Available at:
ftp://ftp.ccs.neu.edu/pub/people/will/howtoread.ps
IEEE 754-1985
IEEE.
IEEE Standard for Binary Floating-Point Arithmetic.
See
Namespaces in XML
World Wide Web Consortium.
Namespaces in XML
. Available at:
RFC 1766
H. Alvestrand, ed.
RFC 1766: Tags for the Identification of Languages
1995. Available at:
RFC 2045
N. Freed and N. Borenstein.
RFC 2045: Multipurpose Internet Mail Extensions
(MIME) Part One: Format of Internet Message Bodies
. 1996. Available at:
RFC 2396
Tim Berners-Lee, et. al.
RFC 2396: Uniform Resource Identifiers (URI):
Generic Syntax.
. 1998. Available at:
RFC 2732
RFC
2732: Format for Literal IPv6 Addresses in URL's
. 1999.
Available at:
RFC 3066
H. Alvestrand, ed.
RFC 3066: Tags for the Identification of Languages
1995. Available at:
Unicode Database
The Unicode Consortium.
The Unicode Character Database
Available at:
XML 1.0 (Second Edition)
World Wide Web Consortium.
Extensible Markup Language (XML) 1.0, Second
Edition.
Available at:
XML Base
World Wide Web Consortium. XML Base.
Available at:
XML Linking Language
World Wide Web Consortium. XML Linking Language (XLink).
Available at:
Note: only the URI reference escaping procedure defined in
Section 5.4 is normatively referenced.
XML Schema Part 1: Structures
XML Schema Part 1: Structures. Available at:
XML Schema Requirements
World Wide Web Consortium. XML Schema Requirements. Available at:
H.2 Non-normative
Character Model
Martin J. Dürst and François Yergeau, eds.
Character Model for the World Wide Web. World Wide Web Consortium
Working Draft. 2001.
Available at:
Gay, DM (1990)
David M. Gay.
Correctly Rounded Binary-Decimal and
Decimal-Binary Conversions.
AT&T Bell Laboratories Numerical
Analysis Manuscript 90-10, November 1990.
Available at:
HTML 4.01
World Wide Web Consortium. Hypertext Markup Language, version 4.01. Available at:
IETF INTERNET-DRAFT: IRIs
M. Dürst and M. Suignard
Internationalized Resource Identifiers
2002. Available at:
International Earth Rotation Service (IERS)
International Earth Rotation Service (IERS).
See
ISO 11404
ISO (International Organization for Standardization).
Language-independent Datatypes.
See
ISO 8601
ISO (International Organization for Standardization).
Representations of dates and times, 1988-06-15.
ISO 8601:1998 Draft Revision
ISO (International Organization for Standardization).
Representations of dates and times, draft revision, 1998.
ISO 8601:2000 Second Edition
ISO (International Organization for Standardization).
Representations of dates and times, second edition, 2000-12-15.
Perl
The Perl Programming Language. See
RDF Schema
World Wide Web Consortium.
RDF Schema Specification.
Available at:
Ruby
World Wide Web Consortium. Ruby Annotation. Available at:
SQL
ISO (International Organization for Standardization).
ISO/IEC
9075-2:1999, Information technology --- Database languages ---
SQL --- Part 2: Foundation (SQL/Foundation)
[Geneva]: International Organization for Standardization, 1999.
See
U.S. Naval Observatory Time Service Department
Information about Leap Seconds
Available at:
Unicode Regular Expression Guidelines
Mark Davis.
Unicode Regular Expression Guidelines
, 1988.
Available at:
XML Schema Language: Part 0 Primer
World Wide Web Consortium. XML Schema Language: Part 0 Primer. Available at:
XSL
World Wide Web Consortium.
Extensible Stylesheet Language (XSL).
Available at:
I Acknowledgements (non-normative)
The following have contributed material to the first edition of this specification:
Asir S. Vedamuthu, webMethods, Inc
Mark Davis, IBM
Co-editor Ashok Malhotra's work on this specification from March 1999 until
February 2001 was supported by IBM. From February 2001 until May 2004 it
was supported by Microsoft.
The editors acknowledge the members of the XML Schema Working Group, the members of other W3C Working Groups, and industry experts in other
forums who have contributed directly or indirectly to the process or content of
creating this document. The Working Group is particularly grateful to Lotus
Development Corp. and IBM for providing teleconferencing facilities.
At the time the first edition of this
specification was published, the members of the XML Schema Working Group
were:
Jim Barnette, Defense Information Systems Agency (DISA)
Paul V. Biron, Health Level Seven
Don Box, DevelopMentor
Allen Brown, Microsoft
Lee Buck, TIBCO Extensibility
Charles E. Campbell, Informix
Wayne Carr, Intel
Peter Chen, Bootstrap Alliance and LSU
David Cleary, Progress Software
Dan Connolly, W3C (
staff contact
Ugo Corda, Xerox
Roger L. Costello, MITRE
Haavard Danielson, Progress Software
Josef Dietl, Mozquito Technologies
David Ezell, Hewlett-Packard Company
Alexander Falk, Altova GmbH
David Fallside, IBM
Dan Fox, Defense Logistics Information Service (DLIS)
Matthew Fuchs, Commerce One
Andrew Goodchild, Distributed Systems Technology Centre (DSTC Pty Ltd)
Paul Grosso, Arbortext, Inc
Martin Gudgin, DevelopMentor
Dave Hollander, Contivo, Inc (
co-chair
Mary Holstege, Invited Expert
Jane Hunter, Distributed Systems Technology Centre (DSTC Pty Ltd)
Rick Jelliffe, Academia Sinica
Simon Johnston, Rational Software
Bob Lojek, Mozquito Technologies
Ashok Malhotra, Microsoft
Lisa Martin, IBM
Noah Mendelsohn, Lotus Development Corporation
Adrian Michel, Commerce One
Alex Milowski, Invited Expert
Don Mullen, TIBCO Extensibility
Dave Peterson, Graphic Communications Association
Jonathan Robie, Software AG
Eric Sedlar, Oracle Corp.
C. M. Sperberg-McQueen, W3C (
co-chair
Bob Streich, Calico Commerce
William K. Stumbo, Xerox
Henry S. Thompson, University of Edinburgh
Mark Tucker, Health Level Seven
Asir S. Vedamuthu, webMethods, Inc
Priscilla Walmsley, XMLSolutions
Norm Walsh, Sun Microsystems
Aki Yoshida, SAP AG
Kongyi Zhou, Oracle Corp.
The XML Schema Working Group has benefited in its work from the
participation and contributions of a number of people not currently
members of the Working Group, including
in particular those named below. Affiliations given are those current at
the time of their work with the WG.
Paula Angerstein, Vignette Corporation
David Beech, Oracle Corp.
Gabe Beged-Dov, Rogue Wave Software
Greg Bumgardner, Rogue Wave Software
Dean Burson, Lotus Development Corporation
Mike Cokus, MITRE
Andrew Eisenberg, Progress Software
Rob Ellman, Calico Commerce
George Feinberg, Object Design
Charles Frankston, Microsoft
Ernesto Guerrieri, Inso
Michael Hyman, Microsoft
Renato Iannella, Distributed Systems Technology Centre (DSTC Pty Ltd)
Dianne Kennedy, Graphic Communications Association
Janet Koenig, Sun Microsystems
Setrag Khoshafian, Technology Deployment International (TDI)
Ara Kullukian, Technology Deployment International (TDI)
Andrew Layman, Microsoft
Dmitry Lenkov, Hewlett-Packard Company
John McCarthy, Lawrence Berkeley National Laboratory
Murata Makoto, Xerox
Eve Maler, Sun Microsystems
Murray Maloney, Muzmo Communication, acting for Commerce One
Chris Olds, Wall Data
Frank Olken, Lawrence Berkeley National Laboratory
Shriram Revankar, Xerox
Mark Reinhold, Sun Microsystems
John C. Schneider, MITRE
Lew Shannon, NCR
William Shea, Merrill Lynch
Ralph Swick, W3C
Tony Stewart, Rivcom
Matt Timmermans, Microstar
Jim Trezzo, Oracle Corp.
Steph Tryphonas, Microstar
The lists given above pertain to the first edition.
At the time work on this second edition was completed,
the membership of the Working Group was:
Leonid Arbouzov, Sun Microsystems
Jim Barnette, Defense Information Systems Agency (DISA)
Paul V. Biron, Health Level Seven
Allen Brown, Microsoft
Charles E. Campbell, Invited expert
Peter Chen, Invited expert
Tony Cincotta, NIST
David Ezell, National Association of Convenience Stores
Matthew Fuchs, Invited expert
Sandy Gao, IBM
Andrew Goodchild, Distributed Systems Technology Centre (DSTC Pty Ltd)
Xan Gregg, Invited expert
Mary Holstege, Mark Logic
Mario Jeckle, DaimlerChrysler
Marcel Jemio, Data Interchange Standards Association
Kohsuke Kawaguchi, Sun Microsystems
Ashok Malhotra, Invited expert
Lisa Martin, IBM
Jim Melton, Oracle Corp
Noah Mendelsohn, IBM
Dave Peterson, Invited expert
Anli Shundi, TIBCO Extensibility
C. M. Sperberg-McQueen, W3C (
co-chair
Hoylen Sue, Distributed Systems Technology Centre (DSTC Pty Ltd)
Henry S. Thompson, University of Edinburgh
Asir S. Vedamuthu, webMethods, Inc
Priscilla Walmsley, Invited expert
Kongyi Zhou, Oracle Corp.
We note with sadness the accidental death of Mario Jeckle
shortly after the completion of work on this document.
In addition to those named above, several
people served on the Working Group during the development
of this second edition:
Oriol Carbo, University of Edinburgh
Tyng-Ruey Chuang, Academia Sinica
Joey Coyle, Health Level 7
Tim Ewald, DevelopMentor
Nelson Hung, Corel
Melanie Kudela, Uniform Code Council
Matthew MacKenzie, XML Global
Cliff Schmidt, Microsoft
John Stanton, Defense Information Systems Agency
John Tebbutt, NIST
Ross Thompson, Contivo
Scott Vorthmann, TIBCO Extensibility