The following items in this specification are implementation-defined:
1. The version of Unicode that is used to construct expressions.
2. The statically-known collations.
3. The implicit timezone.
4. The circumstances in which warnings are raised, and the ways in which warnings are handled.
5. The method by which errors are reported to the external processing environment.
6. Whether the implementation is based on the rules of [XML 1.0] and [XML Names] or the rules of [XML 1.1] and [XML Names 1.1]. One of these sets of rules must be applied consistently by all aspects of the implementation. If the implementation is based on the rules of [XML 1.0], the edition used must be at least Third Edition; the edition used is implementation-defined, but we recommend that
implementations use the latest version.
7. Whether the implementation supports the namespace axis.
8. Any static typing extensions supported by the implementation, if the Static Typing Feature is supported.
Note:
Additional implementation-defined items are listed in [XQuery 1.0 and XPath 2.0 Data Model (Second Edition)] and [XQuery 1.0 and XPath 2.0 Functions and Operators (Second Edition)].
E References
E.1 Normative References
RFC 2119
S. Bradner. Key Words for use in RFCs to Indicate Requirement Levels. IETF RFC 2119. See http://www.ietf.org/rfc/rfc2119.txt.
RFC3986
T. Berners-Lee, R. Fielding, and L. Masinter. Uniform Resource Identifiers (URI): Generic Syntax.
IETF RFC 3986. See http://www.ietf.org/rfc/rfc3986.txt.
RFC3987
M. Duerst and M. Suignard. Internationalized Resource Identifiers (IRIs). IETF RFC 3987. See http://www.ietf.org/rfc/rfc3987.txt.
ISO/IEC 10646
ISO (International Organization for Standardization). ISO/IEC 10646:2003. Information technology—
Universal Multiple-Octet Coded Character Set (UCS), as, from time to time, amended, replaced by a new edition, or expanded by the addition of new parts. [Geneva]: International Organization for Standardization. (See http://www.iso.org for the latest version.)
Unicode
The Unicode Consortium. The Unicode Standard Reading, Mass.: Addison-Wesley, 2003, as updated from time to time by the publication of new versions. See
http://www.unicode.org/standard/versions/ for the latest version and additional information on versions of the standard and of the Unicode Character Database. The version of Unicode to be used is
implementation-defined, but implementations are recommended to use the latest Unicode version.
XML 1.0
World Wide Web Consortium. Extensible Markup Language (XML) 1.0. W3C Recommendation.
See http://www.w3.org/TR/REC-xml/. The edition of XML 1.0 must be no earlier than the Third Edition;
the edition used is implementation-defined, but we recommend that implementations use the latest version.
XML 1.1
World Wide Web Consortium. Extensible Markup Language (XML) 1.1. W3C Recommendation.
See http://www.w3.org/TR/xml11/
XML Base
World Wide Web Consortium. XML Base. W3C Recommendation. See http://www.w3.org/TR/xmlbase/
XML Names
World Wide Web Consortium. Namespaces in XML. W3C Recommendation. See http://www.w3.org/TR/REC-xml-names/
XML Names 1.1
World Wide Web Consortium. Namespaces in XML 1.1. W3C Recommendation. See http://www.w3.org/TR/xml-names11/
XML ID
World Wide Web Consortium. xml:id Version 1.0. W3C Recommendation. See http://www.w3.org/TR/xml-id/
XML Schema
World Wide Web Consortium. XML Schema, Parts 0, 1, and 2 (Second Edition). W3C Recommendation, 28 October 2004. See http://www.w3.org/TR/xmlschema-0/,
http://www.w3.org/TR/xmlschema-1/, and http://www.w3.org/TR/xmlschema-2/.
XQuery 1.0 and XPath 2.0 Data Model (Second Edition)
World Wide Web Consortium. XQuery 1.0 and XPath 2.0 Data Model (XDM) (Second Edition).
W3C Recommendation, 14 December 2010. See http://www.w3.org/TR/xpath-datamodel/.
XQuery 1.0 and XPath 2.0 Formal Semantics (Second Edition)
World Wide Web Consortium. XQuery 1.0 and XPath 2.0 Formal Semantics (Second Edition).
W3C Recommendation, 14 December 2010. See http://www.w3.org/TR/xquery-semantics/.
XQuery 1.0 and XPath 2.0 Functions and Operators (Second Edition)
World Wide Web Consortium. XQuery 1.0 and XPath 2.0 Functions and Operators (Second Edition) W3C Recommendation, 14 December 2010. See http://www.w3.org/TR/xpath-functions/.
XSLT 2.0 and XQuery 1.0 Serialization (Second Edition)
World Wide Web Consortium. XSLT 2.0 and XQuery 1.0 Serialization (Second Edition). W3C Recommendation, 14 December 2010. See http://www.w3.org/TR/xslt-xquery-serialization/.
E.2 Non-normative References
XPath 2.0 Requirements
World Wide Web Consortium. XPath Requirements Version 2.0. W3C Working Draft 22 August 2003. See http://www.w3.org/TR/xpath20req/.
XQuery 1.0: An XML Query Language (Second Edition)
World Wide Web Consortium. XQuery 1.0: An XML Query Language (Second Edition). W3C Recommendation, 14 December 2010. See http://www.w3.org/TR/xquery/.
XSL Transformations (XSLT) Version 2.0 (Second Edition)
World Wide Web Consortium. XSL Transformations (XSLT) 2.0 (Second Edition) W3C Recommendation, 14 December 2010. See http://www.w3.org/TR/xslt20/
Document Object Model
World Wide Web Consortium. Document Object Model (DOM) Level 3 Core Specification. W3C Recommendation, April 7, 2004. See http://www.w3.org/TR/DOM-Level-3-Core/.
XML Infoset
World Wide Web Consortium. XML Information Set. W3C Recommendation 24 October 2001. See http://www.w3.org/TR/xml-infoset/
XPath 1.0
World Wide Web Consortium. XML Path Language (XPath) Version 1.0. W3C Recommendation, Nov. 16, 1999. See http://www.w3.org/TR/xpath/
XPointer
World Wide Web Consortium. XML Pointer Language (XPointer). W3C Last Call Working Draft 8 January 2001. See http://www.w3.org/TR/WD-xptr
E.3 Background Material
Character Model
World Wide Web Consortium. Character Model for the World Wide Web. W3C Working Draft. See http://www.w3.org/TR/charmod/.
XSLT 1.0
World Wide Web Consortium. XSL Transformations (XSLT) 1.0. W3C Recommendation. See http://www.w3.org/TR/xslt
F Conformance
XPath is intended primarily as a component that can be used by other specifications. Therefore, XPath relies on specifications that use it (such as [XPointer] and [XSL Transformations (XSLT) Version 2.0 (Second Edition)]) to specify conformance criteria for XPath in their respective environments.
Specifications that set conformance criteria for their use of XPath must not change the syntactic or semantic definitions of XPath as given in this specification, except by subsetting and/or compatible extensions.
The specification of such a language may describe it as an extension of XPath provided that every expression that conforms to the XPath grammar behaves as described in this specification.
F.1 Static Typing Feature
[Definition: The Static Typing Feature is an optional feature of XPath that provides support for the static semantics defined in [XQuery 1.0 and XPath 2.0 Formal Semantics (Second Edition)], and requires implementations to detect and report type errors during the static analysis phase.] Specifications that use XPath may specify conformance criteria for use of the Static Typing Feature.
If an implementation does not support the Static Typing Feature, but can nevertheless determine during the static analysis phase that an expression will necessarily raise a type error if evaluated at run time, the implementation may raise that error during the static analysis phase. The choice of whether to raise such an error at analysis time is implementation dependent.
F.1.1 Static Typing Extensions
In some cases, the static typing rules defined in [XQuery 1.0 and XPath 2.0 Formal Semantics (Second Edition)] are not very precise (see, for example, the type inference rules for the ancestor axes—parent, ancestor, and ancestor-or-self—and for the function fn:root). Some implementations may wish to support more precise static typing rules.
A conforming implementation that implements the Static Typing Feature may also provide one or more static typing extensions. [Definition: A static typing extension is an implementation-defined type inference rule that infers a more precise static type than that inferred by the type inference rules in [XQuery 1.0 and XPath 2.0 Formal Semantics (Second Edition)].] See Section 6.1.1 Static Typing ExtensionsFS for a formal definition of the constraints on static typing extensions.