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<title>XML Information Set</title>

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<div align="center"><h1>XML Information Set</h1> <h2

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class="nonum">W3C Recommendation 24 October 2001</h2></div> <dl>

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<dt>This version:</dt>

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<dd><a href="http://www.w3.org/TR/2001/REC-xml-infoset-20011024">http://www.w3.org/TR/2001/REC-xml-infoset-20011024</a></dd>

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<dt>Latest version:</dt>

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http://www.w3.org/TR/xml-infoset

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</a></dd>

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<dt>Previous version:</dt>

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http://www.w3.org/TR/2001/PR-xml-infoset-20010810

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</a></dd>

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<dt>Editors:</dt>

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<dd>John Cowan, <a href="mailto:jcowan@reutershealth.com">jcowan@reutershealth.com</a></dd>

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<dd>Richard Tobin, <a href="mailto:richard@cogsci.ed.ac.uk">richard@cogsci.ed.ac.uk</a></dd>

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</dl> <p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice-20000612#Copyright">

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Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.lcs.mit.edu/"><abbr

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title="Massachusetts Institute of Technology">MIT</abbr></a>, <a href="http://www.inria.fr/"><abbr

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title="Institut National de Recherche en

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Informatique et Automatique" lang="fr">INRIA</abbr></a>, <a href="http://www.keio.ac.jp/">

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liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice-20000612#W3C_Trademarks">

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trademark</a>, <a href="http://www.w3.org/Consortium/Legal/copyright-documents-19990405">

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document use</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-software-19980720">

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software licensing</a> rules apply.</p> </div> <hr />

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<div>

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<h2 class="nonum"><a name="abstract">Abstract</a></h2>

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<p>This specification provides a set of definitions for use in other

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specifications that need to refer to the information in an XML document.

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</p>

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</div>

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<div>

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<h2 class="nonum"><a name="status">Status of this Document</a></h2>

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<p><em>This section describes the status of this document at the time of its

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publication. Other documents may supersede this document. The latest status

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of this document series is maintained at the W3C.</em></p>

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<p>This is the W3C

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<a href="/Consortium/Process-20010719/process.html#RecsW3C">Recommendation</a>

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of the XML Information Set.</p>

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<p>This document has been reviewed by W3C Members and other interested parties

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and has been endorsed by the Director as a W3C Recommendation.

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It is a stable document and may be used as reference material or

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cited as a normative reference from another document.

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W3C's role in making the Recommendation is to draw

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attention to the specification and to promote its widespread deployment.

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This enhances the functionality and interoperability of the Web.</p>

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<p>

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This document has been produced by the

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W3C XML Core Working Group as part of the XML Activity

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in the W3C Architecture Domain.

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For background on this work, please see the

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<a href="http://www.w3.org/XML/Activity">XML Activity Statement</a>.</p>

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<p>

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There are patent disclosures associated with the XML Information Set;

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these may be found on the

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<a href="http://www.w3.org/2001/10/02/xml-infoset-IPR-statements.html">XML Infoset Patent Statement page</a>

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in conformance with

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<a href="http://www.w3.org/Consortium/Process-20010719/#ipr">W3C policy</a>.

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</p>

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<p>

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Please report errors in this document to

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<a href="mailto:www-xml-infoset-comments@w3.org">www-xml-infoset-comments@w3.org</a> -

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(<a href="http://lists.w3.org/Archives/Public/www-xml-infoset-comments/">public

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archives</a>).<br/>

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The list of

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<a href="http://www.w3.org/2001/10/02/xml-infoset-errata.html">known errors</a>

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in this specification is available at

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<a href="http://www.w3.org/2001/10/02/xml-infoset-errata.html">http://www.w3.org/2001/10/02/xml-infoset-errata.html</a>

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</p>

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<p>

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The English version of this specification is the only normative version.

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Information about translations of this document is available at

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<a href="http://www.w3.org/XML/#trans">http://www.w3.org/XML/#trans</a>.</p>

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<p>

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A list of <a href="http://www.w3.org/TR">current W3C Recommendations and

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other technical documents</a> can be found at

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<a href="http://www.w3.org/TR">http://www.w3.org/TR</a>.

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</p>

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</div>

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<div>

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<h2 class="nonum">Contents</h2>

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<li><a href="#intro">1. Introduction</a></li>

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<li>

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<a href="#infoitem">2. Information Items</a>

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<li><a href="#infoitem.document">2.1 The Document Information Item</a></li>

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<li><a href="#infoitem.element">2.2 Element Information Items</a></li>

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<li><a href="#infoitem.attribute">2.3 Attribute Information Items</a></li>

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<li><a href="#infoitem.pi">2.4 Processing Instruction Information Items</a></li>

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<li><a href="#infoitem.rse">2.5 Unexpanded Entity Reference Information Items</a></li>

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<li><a href="#infoitem.character">2.6 Character Information Items</a></li>

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<li><a href="#infoitem.comment">2.7 Comment Information Items</a></li>

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<li><a href="#infoitem.doctype">2.8 The Document Type Declaration Information Item</a></li>

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<li><a href="#infoitem.entity.unparsed">2.9 Unparsed Entity Information Items</a></li>

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<li><a href="#infoitem.notation">2.10 Notation Information Items</a></li>

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<li><a href="#infoitem.namespace">2.11 Namespace Information Items</a></li>

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</ul>

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</li>

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<li><a href="#conformance">3. Conformance</a></li>

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<li><a href="#references">Appendix A: References</a></li>

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<li><a href="#reporting">Appendix B: XML 1.0 Reporting Requirements (informative)</a></li>

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<li><a href="#example">Appendix C: Example (informative)</a></li>

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<li><a href="#omitted">Appendix D: What is not in the Information Set</a></li>

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<li><a href="#rdfschema">Appendix E: RDF Schema (informative)</a></li>

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</ul>

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</div>

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<hr />

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<div>

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<h2><a name="intro">1. Introduction </a></h2>

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<p>This specification defines an abstract data set called

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the <dfn><strong>XML Information Set</strong></dfn>

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(<dfn><strong>Infoset</strong></dfn>).

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Its purpose is to provide a consistent set of definitions for use

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in other specifications that need to refer to the information in a well-formed

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XML document <a href="#XML">[XML]</a>.

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</p>

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<p>

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It does not attempt to be exhaustive; the primary criterion for inclusion

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of an information item or property has been that of expected usefulness

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in future specifications. Nor does it constitute a minimum set of

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information that must be returned by an XML processor.

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</p>

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<p>

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An XML document has an information set if it is well-formed and

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satisfies the namespace constraints described

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<a href="#intro.namespaces">below</a>.

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There is no requirement

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for an XML document to be valid in order to have an information set.

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</p>

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<p>

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Information sets may be created by methods (not described in this

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specification) other than parsing an XML document.

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See <a href="#intro.synthetic">Synthetic Infosets</a> below.

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</p>

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<p>

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An XML document's information set consists of a number of

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<dfn><strong>information items</strong></dfn>;

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the information set for any well-formed XML document

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will contain at least a

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<a href="#infoitem.document">document</a> information item

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and several others.

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An information item is an abstract description of some part of an XML

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document: each information item has a set of associated named

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<dfn><strong>properties</strong></dfn>. In this specification, the

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property names are shown in square brackets, <strong>[thus]</strong>.

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The types of information item are listed in

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<a href="#infoitem">section 2</a>.

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</p>

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<p>

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The XML

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Information Set does not require or favor a specific interface or class of

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interfaces. This specification presents the information set as a modified

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tree for the sake of clarity and simplicity, but there is no requirement that

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the XML Information Set be made available through a tree structure; other

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types of interfaces, including (but not limited to) event-based and query-based

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interfaces, are also capable of providing information conforming to the XML

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Information Set.

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</p>

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<p>

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The terms "information set" and "information

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item" are similar in meaning to the generic terms "tree" and "node", as they

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are used in computing. However, the former terms are used in this specification

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to reduce possible confusion with other specific data models. Information

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items do <em>not</em> map one-to-one with the nodes of the DOM or the "tree"

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and "nodes" of the XPath data model.

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</p>

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<p>

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In this specification, the words "must",

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"should", and "may" assume the meanings specified in

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<a href="#RFC2119">[RFC2119]</a>, except that the words do not appear in

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uppercase.

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</p>

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<h3><a name="intro.namespaces">Namespaces</a></h3>

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<p>

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XML 1.0 documents that do not conform to

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<a href="#Namespaces">[Namespaces]</a>,

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though technically well-formed,

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are not considered to have meaningful information sets.

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That is, this specification does not define an information

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set for documents that have element or attribute names containing colons that

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are used in other ways than as prescribed by

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<a href="#Namespaces">[Namespaces]</a>.

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</p>

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<p>

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Furthermore, this specification does not define an information set for

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documents which use relative URI references in namespace declarations.

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This is in accordance with the decision of the W3C XML Plenary Interest

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Group described in <a href="#RelNS">[Relative Namespace URI References]</a>.

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</p>

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<p>

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The value of a [namespace name] property is the normalized value of

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the corresponding namespace attribute; no additional URI escaping is

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applied to it by the processor.

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</p>

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<h3><a name="intro.entities">Entities</a></h3>

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<p>

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An information set describes its XML document with entity

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references already expanded, that is, represented by the information

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items corresponding to their replacement text. However, there are

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various circumstances in which a processor may not perform this

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expansion. An entity may not be declared, or may not be retrievable.

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A non-validating processor may choose not to read all declarations,

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and even if it does, may not expand all external entities. In these

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cases an

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<a href="#infoitem.rse">unexpanded entity reference</a>

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information item is used to represent the entity reference.

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</p>

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<h3><a name="intro.eol">End-of-Line Handling</a></h3>

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<p>

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The values of all properties in the Infoset

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take account of the end-of-line normalization described in

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<a href="#XML">[XML]</a>, 2.11 "End-of-Line Handling".

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</p>

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<p>

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Several information items have a [base URI] or [declaration base URI] property.

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These are computed according to

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<a href="#XMLBase">[XML Base]</a>.

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Note that retrieval of a resource may involve redirection

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at the parser level (for example, in an entity resolver) or below;

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in this case the base URI is the final URI used to retrieve the resource

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after all redirection.

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</p>

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<p>

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The value of these properties does not reflect any URI escaping that

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may be required for retrieval of the resource, but it may include

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escaped characters if these were specified in the document, or returned

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by a server in the case of redirection.

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</p>

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<p>

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In some cases (such as a document read from a string or a pipe) the

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rules in

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may result in a base URI being application

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dependent. In these cases this specification does not define

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the value of the [base URI] or [declaration base URI] property.

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</p>

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<p>

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When resolving relative URIs the [base URI] property should be used in

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preference to the values of xml:base attributes; they may be inconsistent

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in the case of <a href="#intro.synthetic">Synthetic Infosets</a>.

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</p>

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<h3><a name="intro.null">``Unknown'' and ``No Value''</a></h3>

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<p>

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Some properties may sometimes have the value

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<dfn><strong>unknown</strong></dfn> or

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<dfn><strong>no value</strong></dfn>,

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and it is said that a property value is unknown or that a property

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has no value respectively.

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These values are distinct from each other and from all other values.

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In particular they are distinct from the empty string, the empty set,

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and the empty list, each of which simply has no members.

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This specification does not use the term <strong>null</strong> since in some

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communities it has particular connotations which may not match those

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intended here.

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</p>

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<h3><a name="intro.synthetic">Synthetic Infosets</a></h3>

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<p>

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This specification describes the information set resulting from parsing

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an XML document. Information sets may be constructed by other means,

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for example by use of an API such as the DOM or by transforming an

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existing information set.

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</p>

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<p>

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An information set corresponding to a real document will necessarily

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be consistent in various ways; for example the [in-scope namespaces]

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property of an element will be consistent with the [namespace

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attributes] properties of the element and its ancestors. This may not

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be true of an information set constructed by other means; in such a case

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there will be no XML document corresponding to the information set,

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and to serialize it will require resolution of the inconsistencies

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(for example, by outputting namespace declarations that correspond to

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the namespaces in scope).

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</p>

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</div>

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<div>

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<h2><a name="infoitem">2. Information Items</a></h2>

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<p>An

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information set can contain up to eleven different types of information item,

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as explained in the following sections. Every information item has properties.

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For ease of reference, each property is given a name, indicated

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<strong>[thus]</strong>.

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Links to a definition and/or syntax in the XML 1.0

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Recommendation <a href="#XML">[XML]</a> are given for each information item.

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</p>

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<div>

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<h3><a name="infoitem.document">2.1. The Document Information Item</a></h3>

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<p class="xml-def"><em><strong>XML Definition:

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</strong> <a href="http://www.w3.org/TR/REC-xml#dt-xml-doc">document</a> (Section

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2, <cite>Documents</cite>)</em></p> <p class="xml-syntax"><em><strong>

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XML Syntax:</strong> [1] <a href="http://www.w3.org/TR/REC-xml#NT-document">

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Document</a> (Section 2.1, <cite>Well-Formed XML Documents</cite>)</em></p>

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<p>There is exactly one <dfn><strong>document information item</strong></dfn>

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in the information set, and all other information items are accessible from

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the properties of the document information item, either directly or indirectly

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through the properties of other information items.</p> <p>The document information

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item has the following properties:</p> <ol>

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<li><strong>[children]</strong> An ordered list of child information items,

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in document order. The list contains exactly one <a href="#infoitem.element">

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element</a> information item. The list also contains one <a href="#infoitem.pi">

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processing instruction</a> information item for each processing instruction

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outside the document element, and one <a href="#infoitem.comment">comment</a> information item for each comment outside

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the document element. Processing instructions and comments within the DTD

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are excluded. If there is a document type declaration, the list also

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contains a <a href="#infoitem.doctype">document type declaration</a>

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information item.</li>

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<li><strong>[document element]</strong>

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The <a href="#infoitem.element">element</a> information item corresponding to the document element.

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</li>

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<li><strong>[notations]</strong> An unordered set of <a href="#infoitem.notation">

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notation</a> information items, one for each notation declared in the DTD.

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</li>

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<li><strong>[unparsed entities]</strong> An unordered set of

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<a href="#infoitem.entity.unparsed">unparsed entity</a>

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information items, one for each unparsed entity declared

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in the DTD.

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</li>

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<li><strong>[base URI]</strong> The base URI of the document entity.

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</li>

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<li><strong>[character encoding scheme]</strong>

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The name of the character encoding scheme in which the document entity

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is expressed.

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</li>

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<li><strong>[standalone]</strong> An indication of the standalone status of

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the document, either yes or no. This property is derived

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from the optional standalone document declaration in

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the XML declaration at the beginning of the document

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entity, and has no value if there is no standalone document declaration.</li>

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<li><strong>[version]</strong> A string representing the XML version of the

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document. This property is derived from the XML declaration optionally present

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at the beginning of the document entity, and has no value if there is no

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XML declaration.</li>

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<li>

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<strong>[all declarations processed]</strong> This property is not

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strictly speaking part of the infoset of the document. Rather it is

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an indication of whether the processor has read the complete DTD.

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Its value is a boolean. If it is false, then certain

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properties (indicated in their descriptions below) may be unknown.

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If it is true, those properties are never unknown.

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</li>

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</ol></div>

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<div>

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<h3><a name="infoitem.element">2.2. Element Information Items</a></h3>

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<p class="xml-def"><em><strong>XML Definition:</strong> <a href="http://www.w3.org/TR/REC-xml#dt-element">element</a> (Section 3, <cite>

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Logical Structures</cite>)</em></p> <p class="xml-syntax"><em><strong>

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XML Syntax:</strong> [39] <a href="http://www.w3.org/TR/REC-xml#NT-element">

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Element</a> (Section 3, <cite>Logical Structures</cite>)</em></p>

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<p>There is an <dfn><strong>element information item</strong></dfn> for each

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element appearing in the XML document. One of the element information items

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is the value of the [document element] property of the document information

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item, corresponding to the root of the element tree, and all

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other element information items are accessible by recursively following

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its [children] property.</p>

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<p>An element information item has the following

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properties:</p> <ol>

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<li><strong>[namespace name]</strong> The namespace name, if any, of the element

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type. If the element does not belong to a namespace, this property

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has no value.

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</li>

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<li><strong>[local name]</strong> The local part of the element-type name.

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This does not include any namespace prefix or following colon.</li>

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<li><strong>[prefix]</strong> The namespace prefix part of the element-type

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name. If the name is unprefixed, this property

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has no value. Note that namespace-aware applications should use

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the namespace name rather than the prefix to identify elements.

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</li>

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<li><strong>[children]</strong> An ordered list of child information items,

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in document order. This list contains <a href="#infoitem.element">element</a>,

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<a href="#infoitem.pi">processing instruction</a>, <a href="#infoitem.rse">

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unexpanded entity reference</a>, <a href="#infoitem.character">character</a>,

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and <a href="#infoitem.comment">comment</a> information items, one for each

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element, processing instruction, reference to an unprocessed external entity,

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data character, and comment appearing immediately within the current element.

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If the element is empty, this list has no members.</li>

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<li><strong>[attributes]</strong> An unordered set of <a href="#infoitem.attribute">

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attribute</a> information items, one for each of the attributes (specified

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or defaulted from the DTD) of this element. Namespace declarations

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do not appear in this set.

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If the element has no attributes, this

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set has no members.</li>

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<li><strong>[namespace attributes]</strong> An unordered set of <a href="#infoitem.attribute">

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attribute</a> information items, one for each of the namespace

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declarations (specified or defaulted from the DTD) of this element.

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A declaration of the form <code>xmlns=""</code>, which undeclares the

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default namespace, counts as a namespace declaration.

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By definition, all namespace attributes (including

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those named <code>xmlns</code>, whose [prefix] property

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has no value) have a namespace

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URI of <code>http://www.w3.org/2000/xmlns/</code>.

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If the element has no namespace declarations, this set

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has no members.

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</li>

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<li><strong>[in-scope namespaces]</strong> An unordered set

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of <a href="#infoitem.namespace">

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namespace</a> information items, one for each of the namespaces

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in effect for this element. This set always contains an item with

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the prefix <code>xml</code> which is implicitly bound to the

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namespace name <code>http://www.w3.org/XML/1998/namespace</code>.

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It does not contain an item with the prefix <code>xmlns</code> (used

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for declaring namespaces), since

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an application can never encounter an element or attribute with that

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prefix.

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The set will include namespace items corresponding to all of the

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members of [namespace attributes], except for any representing

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a declaration of the form <code>xmlns=""</code>, which does not declare a

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namespace but rather undeclares the default namespace.

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When resolving the prefixes of qualified names this property should be

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used in preference to the [namespace attributes] property; they may be

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inconsistent in the case of <a href="#intro.synthetic">Synthetic

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Infosets</a>.

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</li>

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<li><strong>[base URI]</strong> The base URI of the element.

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</li>

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<li><strong>[parent]</strong> The document or element information item which

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contains this information item in its [children] property.</li>

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</ol></div>

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<div>

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<h3><a name="infoitem.attribute">2.3. Attribute Information Items</a></h3>

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<p class="xml-def"><em><strong>XML Definition:</strong> <a href="http://www.w3.org/TR/REC-xml#dt-attr">attribute</a> (Section 3.1, <cite>

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Start-Tags, End-Tags, and Empty-Element Tags</cite>)</em></p>

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<p class="xml-syntax"><em><strong>XML Syntax:</strong> [41] <a href="http://www.w3.org/TR/REC-xml#NT-Attribute">Attribute</a> (Section 3.1, <cite>

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Start-Tags, End-Tags, and Empty-Element Tags</cite>)</em></p>

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<p>There is an <dfn><strong>attribute information item</strong></dfn> for

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each attribute (specified or defaulted) of each element in the document,

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including those which are namespace declarations. The latter however

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appear as members of an element's [namespace attributes] property rather

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than its [attributes] property.

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</p> <p>Attributes declared in the DTD with no default value

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and not specified in the element's start tag are not represented by

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attribute information items.</p>

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<p>An attribute information item has the

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following properties:</p> <ol>

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<li><strong>[namespace name]</strong> The namespace name, if any, of the attribute.

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Otherwise, this property has no value.

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</li>

486

<li><strong>[local name]</strong> The local part of the attribute name.

487

This does not include any namespace prefix or following colon.</li>

488

<li><strong>[prefix]</strong> The namespace prefix part of the attribute

489

name. If the name is unprefixed, this property

490

has no value.

491

Note that namespace-aware applications should use

492

the namespace name rather than the prefix to identify attributes.

493

</li>

494

<li><strong>[normalized value]</strong> The normalized attribute value (see <a href="http://www.w3.org/TR/REC-xml#AVNormalize">3.3.3 Attribute-Value Normalization

495

</a> <a href="#XML">[XML]</a>).</li>

496

<li><strong>[specified]</strong> A flag indicating whether this attribute

497

was actually specified in the start-tag of its element, or was defaulted from

498

the DTD.</li>

499

<li><strong>[attribute type]</strong> An indication of the type declared for

500

this attribute in the DTD. Legitimate values are ID, IDREF, IDREFS, ENTITY,

501

ENTITIES, NMTOKEN, NMTOKENS, NOTATION, CDATA, and ENUMERATION.

502

If there is no declaration for the attribute, this property has no value.

503

If no declaration has been read, but the [all declarations processed]

504

property of the document information item is false (so there may be an

505

unread declaration), then the value of this property is unknown.

506

Applications should treat no value and unknown as equivalent to

507

a value of CDATA.

508

</li>

509

<li><strong>[references]</strong>

510

If the attribute type is ID, NMTOKEN, NMTOKENS, CDATA, or ENUMERATION,

511

this property has no value. If the attribute type is unknown,

512

the value of this property is unknown. Otherwise (that is,

513

if the attribute type is IDREF, IDREFS, ENTITY, ENTITIES, or NOTATION),

514

the value of this property is an ordered list of the

515

<a href="#infoitem.element">element</a>,

516

<a href="#infoitem.entity.unparsed">unparsed entity</a>, or

517

<a href="#infoitem.notation">notation</a>

518

information items

519

referred to in the attribute value, in the order that they appear there.

520

In this case, if the attribute value is syntactically

521

invalid, this property has no value.

522

If the type is IDREF or IDREFS and any of the IDs does not appear as

523

the value of an ID attribute in the document, or if the type is

524

ENTITY, ENTITIES or NOTATION and no declaration has been read for any

525

of the entities or the notation, then this property has no value

526

or is unknown, depending on whether the [all declarations processed]

527

property of the document information item is true or false.

528

If the type is IDREF or IDREFS and any of the IDs appears as the

529

value of more than one ID attribute in the document, then this property

530

has no value.

531

</li>

532

<li><strong>[owner element]</strong> The element information item which contains

533

this information item in its [attributes] property.</li>

534

</ol> </div>

535

<div>

536

<h3><a name="infoitem.pi">2.4. Processing Instruction Information Items</a></h3>

537

<p class="xml-def"><em><strong>XML Definition:

538

</strong> <a href="http://www.w3.org/TR/REC-xml#dt-pi">processing instruction

539

</a> (Section 2.6, <cite>Processing Instructions</cite>)</em></p>

540

<p class="xml-syntax"><em><strong>XML Syntax:</strong> [16] <a href="http://www.w3.org/TR/REC-xml#NT-PI">PI</a> (Section 2.6, <cite>Processing

541

Instructions</cite>)</em></p> <p>There is a <dfn><strong>

542

processing instruction information item</strong></dfn> for each processing

543

instruction in the document. The XML declaration and text declarations for

544

external parsed entities are not considered processing instructions. </p>

545

<p>A processing instruction information item has the following properties:

546

</p> <ol>

547

<li><strong>[target]</strong> A string representing the target part of the

548

processing instruction (an XML name).</li>

549

<li><strong>[content]</strong> A string representing the content of the processing

550

instruction, excluding the target and any white space immediately following

551

it. If there is no such content, the value of this property will be an empty

552

string.</li>

553

<li><strong>[base URI]</strong> The base URI of the PI.

554

Note that if an infoset is serialized as an XML document, it will not be

555

possible to preserve the base URI of any PI that originally appeared at

556

the top level of an external entity, since there is no syntax for PIs

557

corresponding to the <code>xml:base</code> attribute on elements.

558

</li>

559

<li><strong>[notation]</strong>

560

The <a href="#infoitem.notation">notation</a>

561

information item named by the target.

562

If there is no declaration for a notation with that name, this

563

property has no value. If no declaration has been read, but the [all

564

declarations processed] property of the document information item is

565

false (so there may be an unread declaration), then the value of this

566

property is unknown.

567

</li>

568

<li><strong>[parent]</strong> The document, element, or document type definition

569

information item which contains this information item in its [children] property.

570

</li>

571

</ol> </div>

572

<div>

573

<h3><a name="infoitem.rse">2.5. Unexpanded Entity Reference Information Items</a></h3>

574

575

XML Definition:</strong> Section 4.4.3, <cite><a href="http://www.w3.org/TR/REC-xml#include-if-valid">

576

Included If Validating</a></cite></em></p>

577

<p>A <dfn><strong>unexpanded entity reference information item</strong></dfn>

578

serves as a placeholder by which an XML processor

579

can indicate that it has not expanded an external parsed entity.

580

There is such an information item for each unexpanded

581

reference to an external general entity within the content of an

582

element. A validating XML processor, or a non-validating processor that reads

583

all external general entities, will never generate unexpanded entity reference

584

information items for a valid document.</p>

585

<p>An unexpanded entity reference

586

information item has the following properties:</p> <ol>

587

<li><strong>[name]</strong> The name of the entity referenced.</li>

588

589

<li><strong>[system identifier]</strong>

590

The system identifier of the entity, as it appears in the declaration

591

of the entity, without any additional URI escaping applied by the processor.

592

If there is no declaration for the entity, this property has no

593

value. If no declaration has been read, but the [all declarations

594

processed] property of the document information item is false (so

595

there may be an unread declaration), then the value of this property

596

is unknown.

597

</li>

598

<li>

599

<strong>[public identifier]</strong>

600

The public identifier of the entity, normalized as described in

601

<a href="http://www.w3.org/TR/REC-xml#dt-pubid">4.2.2 External Entities</a>

602

<a href="#XML">[XML]</a>.

603

If there is no declaration for the entity, or the declaration does not

604

include a public identifier, this property has no value. If no

605

declaration has been read, but the [all declarations processed]

606

property of the document information item is false (so there may be an

607

unread declaration), then the value of this property is unknown.

608

</li>

609

<li>

610

<strong>[declaration base URI]</strong>

611

The base URI relative to which the system identifier should be resolved

612

(i.e. the base URI of the resource within which the entity declaration occurs).

613

This is unknown or has no value in the same circumstances as the

614

[system identifier] property.

615

</li>

616

<li><strong>[parent]</strong> The element information item which contains

617

this information item in its [children] property.</li>

618

</ol> </div>

619

<div>

620

<h3><a name="infoitem.character">2.6. Character Information Items</a></h3>

621

<p class="xml-syntax"><em><strong>XML Syntax:</strong>

622

[2] <a href="http://www.w3.org/TR/REC-xml#NT-Char">Char</a> (Section 2.2, <cite>

623

Characters</cite>)</em></p> <p>There is a <dfn><strong>character

624

information item</strong></dfn> for each data character that appears in the

625

document, whether literally, as a character reference, or within a

626

CDATA section.

627

</p>

628

629

<p>Each character

630

is a logically separate information item, but XML applications are free to

631

chunk characters into larger groups as necessary or desirable.</p> <p>A character

632

information item has the following properties:</p> <ol>

633

<li><strong>[character code]</strong> The ISO 10646 character code (in the

634

range 0 to #x10FFFF, though not every value in this range is a legal XML character

635

code) of the character.</li>

636

<li><strong>[element content whitespace]</strong> A boolean indicating whether

637

the character is white space appearing within element content (see <a href="#XML">

638

[XML]</a>, 2.10 "White Space Handling"). Note that validating XML processors

639

are <em>required</em> by XML 1.0 to provide this information.

640

If there is no declaration for the containing element, this property has

641

no value for white space characters.

642

If no declaration has been read, but the [all declarations processed]

643

property of the document information item is false (so there may be an

644

unread declaration), then the value of this property is unknown for

645

white space characters.

646

It is always false for characters that are not white space.

647

</li>

648

<li><strong>[parent]</strong> The element information

649

item which contains this information item in its [children] property.</li>

650

</ol> </div>

651

<div>

652

<h3><a name="infoitem.comment">2.7. Comment Information Items</a></h3>

653

<p class="xml-def"><em><strong>XML Definition:</strong> <a href="http://www.w3.org/TR/REC-xml#dt-comment">comment</a> (Section 2.5, <cite>

654

Comments</cite>)</em></p> <p class="xml-syntax"><em><strong>

655

XML Syntax:</strong> [15] <a href="http://www.w3.org/TR/REC-xml#NT-Comment">

656

Comment</a> (Section 2.5, <cite>Comments</cite>)</em></p> <p>

657

There is a <dfn><strong>comment information item</strong></dfn>

658

for each XML comment in the original document, except for those appearing

659

in the DTD (which are not represented).</p>

660

<p>A comment information item has

661

the following properties:</p> <ol>

662

<li><strong>[content]</strong> A string representing the content of the comment.

663

</li>

664

<li><strong>[parent]</strong> The document or element

665

information item which contains this information item in its [children] property.

666

</li>

667

</ol> </div>

668

<div>

669

<h3><a name="infoitem.doctype">2.8. The Document Type Declaration Information Item</a></h3>

670

671

XML Definition:</strong> <a href="http://www.w3.org/TR/REC-xml#dt-doctype">

672

document type declaration</a> (section 2.8, <cite>Prolog and Document Type

673

Declaration</cite>)</em></p> <p class="xml-syntax"><em><strong>

674

XML Syntax:</strong> [28] <a href="http://www.w3.org/TR/REC-xml#NT-doctypedecl">

675

doctypedecl</a> (section 2.8, <cite>Prolog and Document Type Declaration</cite>)

676

</em></p> <p>If the XML document has a document type declaration,

677

then the information set contains a single <dfn><strong>document type declaration

678

information item</strong></dfn>. Note that entities and notations

679

are provided as

680

properties of the document information item, not the document type declaration

681

information item.</p> <p>A document type declaration information item has

682

the following properties:</p> <ol>

683

<li>

684

<strong>[system identifier]</strong>

685

The system identifier of the external subset, as it appears in the DOCTYPE

686

declaration, without any additional URI escaping applied by the processor.

687

If there is no external subset this property has no value.

688

</li>

689

<li>

690

<strong>[public identifier]</strong>

691

The public identifier of the external subset, normalized as described in

692

<a href="http://www.w3.org/TR/REC-xml#dt-pubid">4.2.2 External Entities</a>

693

<a href="#XML">[XML]</a>.

694

If there is no external subset or if it has no public identifier,

695

this property has no value.

696

</li>

697

<li><strong>[children]</strong> An ordered list of

698

<a href="#infoitem.pi">processing instruction</a> information items

699

representing processing instructions appearing

700

in the DTD, in the original document order. Items from the internal DTD subset

701

appear before those in the external subset.</li>

702

<li><strong>[parent]</strong> The document information item.</li>

703

</ol> </div>

704

705

<div>

706

<h3><a name="infoitem.entity.unparsed">2.9. Unparsed Entity Information Items</a></h3>

707

<p class="xml-def"><em><strong>XML Definition:

708

</strong> <a href="http://www.w3.org/TR/REC-xml#dt-entity">entity</a> (section

709

4, <cite>Physical Structures</cite>)</em></p> <p

710

class="xml-syntax"><em><strong>XML Syntax:</strong> [71] <a href="http://www.w3.org/TR/REC-xml#NT-GEDecl">

711

GEDecl</a> (section 4.2, <cite>Entities</cite>)</em></p>

712

<p>

713

There is an <dfn><strong>unparsed entity information item</strong></dfn>

714

for each unparsed general entity declared in the DTD.

715

</p>

716

<p>

717

An unparsed entity information item has the following properties:

718

</p>

719

<ol>

720

<li>

721

722

The name of the entity.

723

</li>

724

<li>

725

<strong>[system identifier]</strong>

726

The system identifier of the entity, as it appears in the declaration

727

of the entity, without any additional URI escaping applied by the processor.

728

</li>

729

<li>

730

<strong>[public identifier]</strong>

731

The public identifier of the entity, normalized as described in

732

<a href="http://www.w3.org/TR/REC-xml#dt-pubid">4.2.2 External Entities</a>

733

<a href="#XML">[XML]</a>.

734

If the entity has no public identifier, this property has no value.

735

</li>

736

<li>

737

<strong>[declaration base URI]</strong>

738

The base URI relative to which the system identifier should be resolved

739

(i.e. the base URI of the resource within which the entity declaration occurs).

740

</li>

741

<li>

742

<strong>[notation name]</strong>

743

The notation name associated with the entity.

744

</li>

745

<li>

746

<strong>[notation]</strong>

747

The <a href="#infoitem.notation">notation</a>

748

information item named by the notation name.

749

If there is no declaration for a notation with that name, this

750

property has no value. If no declaration has been read, but the [all

751

declarations processed] property of the document information item is

752

false (so there may be an unread declaration), then the value of this

753

property is unknown.

754

</li>

755

</ol>

756

</div>

757

758

<div>

759

<h3><a name="infoitem.notation">2.10. Notation Information Items</a></h3>

760

<p class="xml-def"><em><strong>XML Definition:</strong> <a href="http://www.w3.org/TR/REC-xml#dt-notation">notation</a> (section 4.7, <cite>

761

Notations</cite>)</em></p> <p class="xml-syntax"><em><strong>

762

XML Syntax:</strong> [82] <a href="http://www.w3.org/TR/REC-xml#NT-NotationDecl">

763

NotationDecl</a> (section 4.7, <cite>Notations</cite>)</em></p>

764

<p>There is a <dfn><strong>notation information item</strong></dfn> for

765

each notation declared in the DTD.</p> <p>A notation information item has

766

the following properties:</p> <ol>

767

<li><strong>[name]</strong> The name of the notation.</li>

768

<li><strong>[system identifier]</strong> The system identifier of the notation,

769

as it appears in the declaration of the notation,

770

without any additional URI escaping applied by the processor.

771

If no system identifier was specified, this property has no value.</li>

772

<li><strong>[public identifier]</strong>

773

The public identifier of the notation, normalized as described in

774

<a href="http://www.w3.org/TR/REC-xml#dt-pubid">4.2.2 External Entities</a>

775

<a href="#XML">[XML]</a>.

776

If the notation has no public identifier,

777

this property has no value.</li>

778

<li>

779

<strong>[declaration base URI]</strong>

780

The base URI relative to which the system identifier should be resolved

781

(i.e. the base URI of the resource within which the notation declaration

782

occurs).

783

</li>

784

</ol>

785

</div>

786

787

<div>

788

<h3><a name="infoitem.namespace">2.11. Namespace Information Items</a></h3>

789

<p>

790

Each element in the document has a <dfn><strong>namespace

791

information item</strong></dfn> for each namespace that is in scope

792

for that element.

793

</p> <p>A namespace information item has the following properties:

794

</p> <ol>

795

<li><strong>[prefix]</strong> The prefix whose binding this item describes.

796

Syntactically, this

797

is the part of the attribute name following the <code>xmlns:</code> prefix.

798

If the attribute name is simply <code>xmlns</code>, so that the

799

declaration is of the default namespace, this property

800

has no value.

801

</li>

802

<li><strong>[namespace name]</strong> The namespace name to which the

803

prefix is bound.</li>

804

</ol> </div>

805

806

</div>

807

<div>

808

<h2><a name="conformance">3. Conformance</a></h2>

809

<p>

810

Since the purpose of the Information Set is to provide a set of definitions,

811

conformance is a property of specifications that use those

812

definitions, rather than of implementations.

813

</p>

814

<p>

815

Specifications referring to the Infoset must:

816

</p>

817

<ul>

818

<li>

819

Indicate the information items and properties that are needed to implement

820

the specification. (This indirectly imposes conformance requirements

821

on processors used to implement the specification.)

822

</li>

823

<li>

824

Specify how other information items and properties are treated (for

825

example, they might be passed through unchanged).

826

</li>

827

<li>

828

Note any information required from an XML document that is not defined

829

by the Infoset.

830

</li>

831

<li>

832

Note any difference in the use of terms defined by the Infoset (this

833

should be avoided).

834

</li>

835

</ul>

836

<p>

837

If a specification allows the construction of an infoset that has

838

inconsistencies as described above under

839

<a href="#intro.synthetic">Synthetic Infosets</a>

840

it may describe how

841

those inconsistencies are to be resolved, and should do so if it

842

provides for serialization of the infoset.

843

</p>

844

</div>

845

<div>

846

<h2><a name="references">Appendix A. References</a></h2>

847

<div>

848

<h3><a name="references.normative">Normative References</a></h3>

849

<dl>

850

851

<dd>ISO (International Organization for Standardization). <cite>ISO/IEC 10646-1993

852

(E). Information technology -- Universal Multiple-Octet Coded Character Set

853

(UCS) -- Part 1: Architecture and Basic Multilingual Plane.</cite> [Geneva]:

854

International Organization for Standardization, 1993 (plus amendments AM

855

1 through AM 7). </dd>

856

<dt><strong><a name="Namespaces">Namespaces</a></strong></dt>

857

<dd><cite>Namespaces in XML,</cite> W3C, eds. Tim Bray, Dave Hollander, Andrew

858

Layman. 14 January 1999. Available at <code><a href="http://www.w3.org/TR/REC-xml-names/">

859

http://www.w3.org/TR/REC-xml-names/</a></code>.</dd>

860

861

<dd><cite>Key words for use in RFCs to Indicate Requirement Levels,</cite>

862

ed. S. Bradner. March 1997. Available at <code><a href="http://www.ietf.org/rfc/rfc2119.txt">

863

http://www.ietf.org/rfc/rfc2119.txt</a></code>.</dd>

864

865

<dd><cite>Extensible Markup Language (XML) 1.0 (Second Edition),</cite>

866

W3C, eds. Tim Bray, Jean Paoli, C.M. Sperberg-McQueen, Eve Maler. 6 October 2000.

867

Available at <code><a href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></code>.

868

</dd>

869

870

<dd><cite>XML Base,</cite> W3C, ed. Jonathan Marsh. February 2000. Available at <code><a href="http://www.w3.org/TR/xmlbase">http://www.w3.org/TR/xmlbase</a></code>.

871

</dd>

872

</dl>

873

</div>

874

<div>

875

<h3><a name="references.informative">Informative References</a></h3>

876

<dl>

877

878

<dd><cite>Document Object Model (DOM) Level 1 Specification,</cite> W3C, eds. Vidur

879

Apparao, Steve Byrne, Mike Champion, et al. 1 October 1998. Available

880

at <code><a href="http://www.w3.org/TR/REC-DOM-Level-1/">http://www.w3.org/TR/REC-DOM-Level-1/</a></code>.</dd>

881

<dt><strong><a name="XPointer-Liaison">XPointer-Liaison</a></strong></dt>

882

<dd><cite>XPointer-Information Set Liaison Statement,</cite> W3C, ed. Steven J.

883

DeRose. 24 February 1999. Available at <code><a href="http://www.w3.org/TR/NOTE-xptr-infoset-liaison">

884

http://www.w3.org/TR/NOTE-xptr-infoset-liaison</a></code>.</dd>

885

<dt><strong><a name="RelNS">Relative Namespace URI References</a></strong></dt>

886

<dd>

887

<cite>Results of W3C XML Plenary Ballot on relative URI References

888

in namespace declarations, 3-17 July 2000,</cite> W3C, eds. Dave Hollander,

889

C. M. Sperberg-McQueen. 6 September 2000. Available at

890

<code><a href="http://www.w3.org/2000/09/xppa">http://www.w3.org/2000/09/xppa</a></code>.

891

</dd>

892

<dt><strong><a name="RDFNote">RDF Schema for the XML Information Set</a></strong></dt>

893

<dd>

894

<cite>RDF Schema for the XML Information Set,</cite> W3C, ed. Richard Tobin. 6 April 2001. Available at

895

<code><a href="http://www.w3.org/TR/xml-infoset-rdfs">http://www.w3.org/TR/xml-infoset-rdfs</a></code>.

896

</dd>

897

</dl></div></div>

898

<div>

899

<h2><a name="reporting">Appendix B: XML 1.0 Reporting Requirements (informative)</a></h2>

900

<p>Although the XML 1.0 Recommendation <a href="#XML">[XML]</a> is primarily concerned with XML syntax, it also includes

901

some specific reporting requirements for XML processors.</p> <p>The reporting

902

requirements include errors, which are outside the scope of this specification,

903

and document information. All of the XML 1.0 requirements for document information

904

reporting have been integrated into the XML Information Set; numbers in parentheses

905

refer to sections of the XML Recommendation:</p> <ol>

906

<li>An XML processor must always provide all characters in a document that

907

are not part of markup to the application (2.10).</li>

908

<li>A validating XML processor must inform the application which of the character

909

data in a document is white space appearing within element content (2.10).

910

</li>

911

<li>An XML processor must normalize line-ends to LF before passing

912

them to the application (2.11).</li>

913

<li>An XML processor must normalize the value of attributes according to the

914

rules in clause 3.3.3 before passing them to the application.

915

</li>

916

<li>An XML processor must pass the names and external identifiers (system

917

identifiers, public identifiers or both) of declared notations to the application

918

(4.7).</li>

919

<li>When the name of an unparsed entity appears as the explicit or default

920

value of an ENTITY or ENTITIES attribute, an XML processor must provide the

921

names, system identifiers, and (if present) public identifiers of both the

922

entity and its notation to the application (4.6, 4.7).</li>

923

<li>An XML processor must pass processing instructions to the application

924

(2.6).</li>

925

<li>An XML processor (necessarily a non-validating one) that does not include

926

the replacement text of an external parsed entity in place of an entity reference

927

must notify the application that it recognized but did not read the entity

928

(4.4.3).</li>

929

<li>A validating XML processor must include the replacement text of an entity

930

in place of an entity reference (5.2).</li>

931

<li>An XML processor must supply the default value of attributes

932

declared in the DTD for a given element type but not appearing in the element's

933

start tag (3.3.2).</li>

934

</ol>

935

<div>

936

<h2><a name="example">Appendix C: Example (informative)</a></h2>

937

<p>

938

Consider the following example XML document:

939

</p>

940

941

942

943

<msg:message doc:date="19990421"

944

xmlns:doc="http://doc.example.org/namespaces/doc"

945

xmlns:msg="http://message.example.org/"

946

>Phone home!</msg:message></pre>

947

948

<p>

949

The information set for this XML document

950

contains the following information items:

951

</p>

952

953

<ul>

954

955

<li>A <a href="#infoitem.document">document</a> information item.</li>

956

957

<li>

958

An <a href="#infoitem.element">element</a> information item

959

with namespace name "<code>http://message.example.org/</code>",

960

local part "<code>message</code>",

961

and prefix "<code>msg</code>".

962

</li>

963

964

<li>

965

An <a href="#infoitem.attribute">attribute</a> information item with the

966

namespace name "<code>http://doc.example.org/namespaces/doc</code>",

967

local part "<code>date</code>",

968

prefix "<code>doc</code>",

969

and normalized value "<code>19990421</code>".

970

</li>

971

972

<li>

973

Three <a href="#infoitem.namespace">namespace</a> information items

974

for the

975

<code>http://www.w3.org/XML/1998/namespace</code>,

976

<code>http://doc.example.org/namespaces/doc</code>, and

977

<code>http://message.example.org/</code> namespaces.

978

</li>

979

980

<li>

981

Two <a href="#infoitem.attribute">attribute</a> information items

982

for the namespace attributes.

983

</li>

984

985

<li>

986

Eleven <a href="#infoitem.character">character</a> information items

987

for the character data.

988

</li>

989

990

</ul>

991

992

</div>

993

994

<div>

995

<h2><a name="omitted">Appendix D: What is not in the Information Set</a></h2>

996

<p>The following information is not represented in the

997

current version of the XML Information Set (this list is not intended to

998

be exhaustive):</p> <ol>

999

<li>The content models of elements, from ELEMENT declarations in the DTD.

1000

</li>

1001

<li>The grouping and ordering of attribute declarations in ATTLIST declarations.

1002

</li>

1003

<li>The document type name.</li>

1004

<li>White space outside the document element.</li>

1005

<li>White space immediately following the target name of a PI.</li>

1006

<li>Whether characters are represented by character references.</li>

1007

<li>The difference between the two forms of an empty element: <code><foo/>

1008

</code> and <code><foo></foo></code>.</li>

1009

<li>White space within start-tags (other than significant white space in attribute

1010

values) and end-tags.</li>

1011

<li>The difference between CR, CR-LF, and LF line termination.</li>

1012

<li>The order of attributes within a start-tag.</li>

1013

<li>The order of declarations within the DTD.</li>

1014

<li>The boundaries of conditional sections in the DTD.</li>

1015

<li>The boundaries of parameter entities in the DTD.</li>

1016

<li>Comments in the DTD.</li>

1017

<li>The location of declarations (whether in internal or external subset or

1018

parameter entities).</li>

1019

<li>Any ignored declarations, including those within an IGNORE conditional

1020

section, as well as entity and attribute declarations ignored because previous

1021

declarations override them. </li>

1022

<li>The kind of quotation marks (single or double) used to quote attribute

1023

values.</li>

1024

<li>The boundaries of general parsed entities.</li>

1025

<li>The boundaries of CDATA marked sections.</li>

1026

<li>The default value of attributes declared in the DTD.</li>

1027

</ol>

1028

<div>

1029

<h2><a name="rdfschema">Appendix E: RDF Schema (informative)</a></h2>

1030

<p>

1031

See <a href="#RDFNote">RDF Schema for the XML Information Set</a> for a formal

1032

characterization of the Infoset.

1033

</p>

1034

</div> </div> </div></body>

1035

</html>