Alessandro Bonazzi
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html lang="EN"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Extensible Markup Language (XML) 1.0 (Second Edition) -- Review Version</title><style type="text/css">
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</style><link rel="stylesheet" type="text/css" href="W3C-REC.css"></head><body>
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<div class="head"><p><a href="http://www.w3.org/"><img src="http://www.w3.org/Icons/w3c_home" alt="W3C" height="48" width="72"></a></p>
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<h1>Extensible Markup Language (XML) 1.0 (Second Edition)</h1>
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<h2>W3C Recommendation 6 October 2000</h2><dl><dt>This version:</dt><dd><a href="http://www.w3.org/TR/2000/REC-xml-20001006">http://www.w3.org/TR/2000/REC-xml-20001006</a>
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(<a href="http://www.w3.org/TR/2000/REC-xml-20001006.html">XHTML</a>, <a href="http://www.w3.org/TR/2000/REC-xml-20001006.xml">XML</a>, <a href="http://www.w3.org/TR/2000/REC-xml-20001006.pdf">PDF</a>, <a href="http://www.w3.org/TR/2000/REC-xml-20001006-review.html">XHTML
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review version</a> with color-coded revision indicators)</dd><dt>Latest version:</dt><dd><a href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></dd><dt>Previous versions:</dt><dd><a href="http://www.w3.org/TR/2000/WD-xml-2e-20000814"> http://www.w3.org/TR/2000/WD-xml-2e-20000814</a>
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<a href="http://www.w3.org/TR/1998/REC-xml-19980210"> http://www.w3.org/TR/1998/REC-xml-19980210</a> </dd><dt>Editors:</dt>
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<dd>Tim Bray, Textuality and Netscape <a href="mailto:tbray@textuality.com"><tbray@textuality.com></a></dd>
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<dd>Jean Paoli, Microsoft <a href="mailto:jeanpa@microsoft.com"><jeanpa@microsoft.com></a></dd>
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<dd><span class="diff-chg">C. M. Sperberg-McQueen, University
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of Illinois at Chicago and Text Encoding Initiative <a href="mailto:cmsmcq@uic.edu"><cmsmcq@uic.edu></a></span></dd>
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<dd><span class="diff-add">Eve Maler, Sun Microsystems,
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Inc. <a href="mailto:elm@east.sun.com"><eve.maler@east.sun.com></a> - Second Edition</span></dd>
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</dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a><EFBFBD><EFBFBD><EFBFBD>2000<EFBFBD><a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup><EFBFBD></sup> (<a href="http://www.lcs.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>, <a href="http://www.inria.fr/"><abbr lang="fr" title="Institut National de Recherche en Informatique et Automatique">INRIA</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>, <a href="http://www.w3.org/Consortium/Legal/copyright-documents-19990405">document use</a>, and <a href="http://www.w3.org/Consortium/Legal/copyright-software-19980720">software licensing</a> rules apply.</p></div><hr><div id="abstract">
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<h2><a name="abstract">Abstract</a></h2>
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<p>The Extensible Markup Language (XML) is a subset of SGML that is completely
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described in this document. Its goal is to enable generic SGML to be served,
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received, and processed on the Web in the way that is now possible with HTML.
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XML has been designed for ease of implementation and for interoperability
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with both SGML and HTML.</p>
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</div><div id="status">
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<h2><a name="status">Status of this Document</a></h2>
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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. It is a stable
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document and may be used as reference material or cited as a normative reference
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from another document. W3C's role in making the Recommendation is to draw
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attention to the specification and to promote its widespread deployment. This
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enhances the functionality and interoperability of the Web.</p>
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<p>This document specifies a syntax created by subsetting an existing, widely
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used international text processing standard (Standard Generalized Markup Language,
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ISO 8879:1986(E) as amended and corrected) for use on the World Wide Web.
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It is a product of the W3C XML Activity, details of which can be found at <a href="http://www.w3.org/XML/">http://www.w3.org/XML</a>. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E100">[E100]</a>
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The English version of this specification is the only normative version. However,
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for translations of this document, see <a href="http://www.w3.org/XML/#trans">http://www.w3.org/XML/#trans</a>. </span>A
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list of current W3C Recommendations and other technical documents can be found
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at <a href="http://www.w3.org/TR/">http://www.w3.org/TR</a>.</p>
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<div class="diff-del"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E66">[E66]</a>This
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specification uses the term URI, which is defined by <a href="#Berners-Lee">[Berners-Lee et al.]</a>,
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a work in progress expected to update <a href="#RFC1738">[IETF RFC1738]</a> and <a href="#RFC1808">[IETF RFC1808]</a>.</p></div>
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<div class="diff-add"><p>This second edition is <em>not</em> a new version of XML (first published 10 February 1998);
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it merely incorporates the changes dictated by the first-edition errata (available
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at <a href="http://www.w3.org/XML/xml-19980210-errata">http://www.w3.org/XML/xml-19980210-errata</a>)
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as a convenience to readers. The errata list for this second edition is available
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at <a href="http://www.w3.org/XML/xml-V10-2e-errata">http://www.w3.org/XML/xml-V10-2e-errata</a>.</p></div>
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<p>Please report errors in this document to <a href="mailto:xml-editor@w3.org">xml-editor@w3.org</a><span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E101">[E101]</a>; <a href="http://lists.w3.org/Archives/Public/xml-editor">archives</a> are available</span>.</p>
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<div class="diff-add"><div class="note"><p class="prefix"><b>Note:</b></p>
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<p>C. M. Sperberg-McQueen's affiliation has changed since the publication
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of the first edition. He is now at the World Wide Web Consortium, and can
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be contacted at <a href="mailto:cmsmcq@w3.org">cmsmcq@w3.org</a>.</p>
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</div></div>
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</div>
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<div class="toc">
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<h2><a name="contents">Table of Contents</a></h2><p class="toc">1 <a href="#sec-intro">Introduction</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>1.1 <a href="#sec-origin-goals">Origin and Goals</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>1.2 <a href="#sec-terminology">Terminology</a><br>2 <a href="#sec-documents">Documents</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.1 <a href="#sec-well-formed">Well-Formed XML Documents</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.2 <a href="#charsets">Characters</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.3 <a href="#sec-common-syn">Common Syntactic Constructs</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.4 <a href="#syntax">Character Data and Markup</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.5 <a href="#sec-comments">Comments</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.6 <a href="#sec-pi">Processing Instructions</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.7 <a href="#sec-cdata-sect">CDATA Sections</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.8 <a href="#sec-prolog-dtd">Prolog and Document Type Declaration</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.9 <a href="#sec-rmd">Standalone Document Declaration</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.10 <a href="#sec-white-space">White Space Handling</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.11 <a href="#sec-line-ends">End-of-Line Handling</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>2.12 <a href="#sec-lang-tag">Language Identification</a><br>3 <a href="#sec-logical-struct">Logical Structures</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>3.1 <a href="#sec-starttags">Start-Tags, End-Tags, and Empty-Element Tags</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>3.2 <a href="#elemdecls">Element Type Declarations</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>3.2.1 <a href="#sec-element-content">Element Content</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>3.2.2 <a href="#sec-mixed-content">Mixed Content</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>3.3 <a href="#attdecls">Attribute-List Declarations</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>3.3.1 <a href="#sec-attribute-types">Attribute Types</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>3.3.2 <a href="#sec-attr-defaults">Attribute Defaults</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>3.3.3 <a href="#AVNormalize">Attribute-Value
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Normalization</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>3.4 <a href="#sec-condition-sect">Conditional Sections</a><br>4 <a href="#sec-physical-struct">Physical Structures</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.1 <a href="#sec-references">Character and Entity References</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.2 <a href="#sec-entity-decl">Entity Declarations</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.2.1 <a href="#sec-internal-ent">Internal Entities</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.2.2 <a href="#sec-external-ent">External Entities</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.3 <a href="#TextEntities">Parsed Entities</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.3.1 <a href="#sec-TextDecl">The Text Declaration</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.3.2 <a href="#wf-entities">Well-Formed Parsed Entities</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.3.3 <a href="#charencoding">Character Encoding in Entities</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.4 <a href="#entproc">XML Processor Treatment of Entities and References</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.4.1 <a href="#not-recognized">Not Recognized</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.4.2 <a href="#included">Included</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.4.3 <a href="#include-if-valid">Included If Validating</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.4.4 <a href="#forbidden">Forbidden</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.4.5 <a href="#inliteral">Included in Literal</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.4.6 <a href="#notify">Notify</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.4.7 <a href="#bypass">Bypassed</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.4.8 <a href="#as-PE">Included as PE</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.5 <a href="#intern-replacement">Construction of Internal Entity Replacement Text</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.6 <a href="#sec-predefined-ent">Predefined Entities</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.7 <a href="#Notations">Notation Declarations</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>4.8 <a href="#sec-doc-entity">Document Entity</a><br>5 <a href="#sec-conformance">Conformance</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>5.1 <a href="#proc-types">Validating and Non-Validating Processors</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>5.2 <a href="#safe-behavior">Using XML Processors</a><br>6 <a href="#sec-notation">Notation</a><br></p>
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<h3>Appendices</h3><p class="toc">A <a href="#sec-bibliography">References</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>A.1 <a href="#sec-existing-stds">Normative References</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>A.2 <a href="#null">Other References</a><br>B <a href="#CharClasses">Character Classes</a><br>C <a href="#sec-xml-and-sgml">XML and SGML</a> (Non-Normative)<br>D <a href="#sec-entexpand">Expansion of Entity and Character References</a> (Non-Normative)<br>E <a href="#determinism">Deterministic Content Models</a> (Non-Normative)<br>F <a href="#sec-guessing">Autodetection
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of Character Encodings</a> (Non-Normative)<br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>F.1 <a href="#sec-guessing-no-ext-info">Detection Without External Encoding Information</a><br><EFBFBD><EFBFBD><EFBFBD><EFBFBD>F.2 <a href="#sec-guessing-with-ext-info">Priorities in the Presence of External Encoding Information</a><br>G <a href="#sec-xml-wg">W3C XML Working Group</a> (Non-Normative)<br>H <a href="#sec-core-wg">W3C XML Core Group</a> (Non-Normative)<br>I <a href="#id2683713">Production Notes</a> (Non-Normative)<br></p></div><hr><div class="body">
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<div class="div1">
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<h2><a name="sec-intro"></a>1 Introduction</h2>
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<p>Extensible Markup Language, abbreviated XML, describes a class of data
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objects called <a title="XML Document" href="#dt-xml-doc">XML documents</a> and partially
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describes the behavior of computer programs which process them. XML is an
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application profile or restricted form of SGML, the Standard Generalized Markup
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Language <a href="#ISO8879">[ISO 8879]</a>. By construction, XML documents are conforming
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SGML documents.</p>
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<p>XML documents are made up of storage units called <a title="Entity" href="#dt-entity">entities</a>,
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which contain either parsed or unparsed data. Parsed data is made up of <a title="Character" href="#dt-character">characters</a>, some of which form <a title="Character Data" href="#dt-chardata">character
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data</a>, and some of which form <a title="Markup" href="#dt-markup">markup</a>.
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Markup encodes a description of the document's storage layout and logical
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structure. XML provides a mechanism to impose constraints on the storage layout
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and logical structure.</p>
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<p>[<a name="dt-xml-proc" title="XML Processor">Definition</a>: A software module called
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an <b>XML processor</b> is used to read XML documents and provide access
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to their content and structure.] [<a name="dt-app" title="Application">Definition</a>: It
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is assumed that an XML processor is doing its work on behalf of another module,
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called the <b>application</b>.] This specification describes
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the required behavior of an XML processor in terms of how it must read XML
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data and the information it must provide to the application.</p>
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<div class="div2">
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<h3><a name="sec-origin-goals"></a>1.1 Origin and Goals</h3>
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<p>XML was developed by an XML Working Group (originally known as the SGML
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Editorial Review Board) formed under the auspices of the World Wide Web Consortium
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(W3C) in 1996. It was chaired by Jon Bosak of Sun Microsystems with the active
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participation of an XML Special Interest Group (previously known as the SGML
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Working Group) also organized by the W3C. The membership of the XML Working
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Group is given in an appendix. Dan Connolly served as the WG's contact with
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the W3C.</p>
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<p>The design goals for XML are:</p>
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<ol>
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<li><p>XML shall be straightforwardly usable over the Internet.</p></li>
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<li><p>XML shall support a wide variety of applications.</p></li>
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<li><p>XML shall be compatible with SGML.</p></li>
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<li><p>It shall be easy to write programs which process XML documents.</p>
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</li>
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<li><p>The number of optional features in XML is to be kept to the absolute
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minimum, ideally zero.</p></li>
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<li><p>XML documents should be human-legible and reasonably clear.</p></li>
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<li><p>The XML design should be prepared quickly.</p></li>
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<li><p>The design of XML shall be formal and concise.</p></li>
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<li><p>XML documents shall be easy to create.</p></li>
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<li><p>Terseness in XML markup is of minimal importance.</p></li>
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</ol>
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<p>This specification, together with associated standards (Unicode and ISO/IEC
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10646 for characters, Internet RFC 1766 for language identification tags,
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ISO 639 for language name codes, and ISO 3166 for country name codes), provides
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all the information necessary to understand XML Version 1.0 and
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construct computer programs to process it.</p>
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<p>This version of the XML specification may be distributed freely, as long as
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all text and legal notices remain intact.</p>
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</div>
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<div class="div2">
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<h3><a name="sec-terminology"></a>1.2 Terminology</h3>
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<p>The terminology used to describe XML documents is defined in the body of
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this specification. The terms defined in the following list are used in building
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those definitions and in describing the actions of an XML processor: </p><dl>
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<dt class="label">may</dt>
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<dd>
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<p>[<a name="dt-may" title="May">Definition</a>: Conforming documents and XML processors
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are permitted to but need not behave as described.]</p>
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</dd>
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<dt class="label">must</dt>
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<dd>
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<p>[<a name="dt-must" title="Must">Definition</a>: Conforming documents and XML processors
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are required to behave as described; otherwise they are in error. ]</p>
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</dd>
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<dt class="label">error</dt>
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<dd>
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<p>[<a name="dt-error" title="Error">Definition</a>: A violation of the rules of this specification;
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results are undefined. Conforming software may detect and report an error
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and may recover from it.]</p>
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</dd>
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<dt class="label">fatal error</dt>
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<dd>
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<p>[<a name="dt-fatal" title="Fatal Error">Definition</a>: An error which a conforming <a title="XML Processor" href="#dt-xml-proc">XML processor</a> must detect and report to the application.
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After encountering a fatal error, the processor may continue processing the
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data to search for further errors and may report such errors to the application.
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In order to support correction of errors, the processor may make unprocessed
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data from the document (with intermingled character data and markup) available
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to the application. Once a fatal error is detected, however, the processor
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must not continue normal processing (i.e., it must not continue to pass character
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data and information about the document's logical structure to the application
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in the normal way).]</p>
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</dd>
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<dt class="label">at user option</dt>
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<dd>
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<p>[<a name="dt-atuseroption" title="At user option">Definition</a>: Conforming software
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may or must (depending on the modal verb in the sentence) behave as described;
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if it does, it must provide users a means to enable or disable the behavior
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described.]</p>
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</dd>
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<dt class="label">validity constraint</dt>
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<dd>
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<p>[<a name="dt-vc" title="Validity constraint">Definition</a>: A rule which applies to
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all <a title="Validity" href="#dt-valid">valid</a> XML documents. Violations of validity
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constraints are errors; they must, at user option, be reported by <a title="Validating Processor" href="#dt-validating">validating XML processors</a>.]</p>
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</dd>
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<dt class="label">well-formedness constraint</dt>
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<dd>
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<p>[<a name="dt-wfc" title="Well-formedness constraint">Definition</a>: A rule which applies
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to all <a title="Well-Formed" href="#dt-wellformed">well-formed</a> XML documents. Violations
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of well-formedness constraints are <a title="Fatal Error" href="#dt-fatal">fatal errors</a>.]</p>
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</dd>
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<dt class="label">match</dt>
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<dd>
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<p>[<a name="dt-match" title="match">Definition</a>: (Of strings or names:) Two strings
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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. <span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E85">[E85]</a>At
|
||
user option, processors may normalize such characters to some canonical form. </span>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. (Of content and content models:) An element matches its declaration
|
||
when it conforms in the fashion described in the constraint <a href="#elementvalid"><b>[VC: Element Valid]</b></a>.]</p>
|
||
</dd>
|
||
<dt class="label">for compatibility</dt>
|
||
<dd>
|
||
<p>[<a name="dt-compat" title="For Compatibility">Definition</a>: <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E87">[E87]</a>Marks
|
||
a sentence describing</span> a feature of XML included solely to ensure
|
||
that XML remains compatible with SGML.]</p>
|
||
</dd>
|
||
<dt class="label">for interoperability</dt>
|
||
<dd>
|
||
<p>[<a name="dt-interop" title="For interoperability">Definition</a>: <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E87">[E87]</a>Marks
|
||
a sentence describing</span> a non-binding recommendation included to increase
|
||
the chances that XML documents can be processed by the existing installed
|
||
base of SGML processors which predate the WebSGML Adaptations Annex to ISO 8879.]</p>
|
||
</dd>
|
||
</dl><p></p>
|
||
</div>
|
||
</div>
|
||
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-documents"></a>2 Documents</h2>
|
||
<p>[<a name="dt-xml-doc" title="XML Document">Definition</a>: A data object is an <b>XML
|
||
document</b> if it is <a title="Well-Formed" href="#dt-wellformed">well-formed</a>,
|
||
as defined in this specification. A well-formed XML document may in addition
|
||
be <a title="Validity" href="#dt-valid">valid</a> if it meets certain further constraints.]</p>
|
||
<p>Each XML document has both a logical and a physical structure. Physically,
|
||
the document is composed of units called <a title="Entity" href="#dt-entity">entities</a>.
|
||
An entity may <a title="Entity Reference" href="#dt-entref">refer</a> to other entities to
|
||
cause their inclusion in the document. A document begins in a "root"
|
||
or <a title="Document Entity" href="#dt-docent">document entity</a>. Logically, the document
|
||
is composed of declarations, elements, comments, character references, and
|
||
processing instructions, all of which are indicated in the document by explicit
|
||
markup. The logical and physical structures must nest properly, as described
|
||
in <a href="#wf-entities"><b>4.3.2 Well-Formed Parsed Entities</b></a>.</p>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-well-formed"></a>2.1 Well-Formed XML Documents</h3>
|
||
<p>[<a name="dt-wellformed" title="Well-Formed">Definition</a>: A textual object is a <b>well-formed</b>
|
||
XML document if:]</p>
|
||
<ol>
|
||
<li><p>Taken as a whole, it matches the production labeled <a href="#NT-document">document</a>.</p>
|
||
</li>
|
||
<li><p>It meets all the well-formedness constraints given in this specification.</p>
|
||
</li>
|
||
<li><p>Each of the <a title="Text Entity" href="#dt-parsedent">parsed entities</a>
|
||
which is referenced directly or indirectly within the document is <a title="Well-Formed" href="#dt-wellformed">well-formed</a>.</p></li>
|
||
</ol>
|
||
|
||
<h5>Document</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-document"></a>[1]<5D><><EFBFBD></td><td><code>document</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-prolog">prolog</a> <a href="#NT-element">element</a> <a href="#NT-Misc">Misc</a>*</code></td><xsltdebug></xsltdebug></tr></tbody></table>
|
||
<p>Matching the <a href="#NT-document">document</a> production implies that:</p>
|
||
<ol>
|
||
<li><p>It contains one or more <a title="Element" href="#dt-element">elements</a>.</p>
|
||
</li>
|
||
|
||
<li><p>[<a name="dt-root" title="Root Element">Definition</a>: There is exactly one element,
|
||
called the <b>root</b>, or document element, no part of which appears
|
||
in the <a title="Content" href="#dt-content">content</a> of any other element.] <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E17">[E17]</a>For
|
||
all other elements, if the <a title="Start-Tag" href="#dt-stag">start-tag</a> is in
|
||
the content of another element, the <a title="End Tag" href="#dt-etag">end-tag</a>
|
||
is in the content of the same element.</span> More simply stated, the elements,
|
||
delimited by start- and end-tags, nest properly within each other.</p></li>
|
||
</ol>
|
||
<p>[<a name="dt-parentchild" title="Parent/Child">Definition</a>: As a consequence of this,
|
||
for each non-root element <code>C</code> in the document, there is one other element <code>P</code>
|
||
in the document such that <code>C</code> is in the content of <code>P</code>, but
|
||
is not in the content of any other element that is in the content of <code>P</code>. <code>P</code>
|
||
is referred to as the <b>parent</b> of <code>C</code>, and <code>C</code> as
|
||
a <b>child</b> of <code>P</code>.]</p>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="charsets"></a>2.2 Characters</h3>
|
||
<p>[<a name="dt-text" title="Text">Definition</a>: A parsed entity contains <b>text</b>,
|
||
a sequence of <a title="Character" href="#dt-character">characters</a>, which may
|
||
represent markup or character data.] [<a name="dt-character" title="Character">Definition</a>: A <b>character</b>
|
||
is an atomic unit of text as specified by ISO/IEC 10646 <a href="#ISO10646">[ISO/IEC 10646]</a> <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</a>(see
|
||
also <a href="#ISO10646-2000">[ISO/IEC 10646-2000]</a>)</span>. Legal characters are tab, carriage
|
||
return, line feed, and the legal <span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E35">[E35]</a>graphic </span>characters
|
||
of Unicode and ISO/IEC 10646. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E69">[E69]</a>The
|
||
versions of these standards cited in <a href="#sec-existing-stds"><b>A.1 Normative References</b></a> were
|
||
current at the time this document was prepared. New characters may be added
|
||
to these standards by amendments or new editions. Consequently, XML processors
|
||
must accept any character in the range specified for <a href="#NT-Char">Char</a>.</span>
|
||
The use of "compatibility characters", as defined in section
|
||
6.8 of <a href="#Unicode">[Unicode]</a> <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</a>(see
|
||
also D21 in section 3.6 of <a href="#Unicode3">[Unicode3]</a>)</span>, is discouraged.]</p>
|
||
|
||
<h5>Character Range</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-Char"></a>[2]<5D><><EFBFBD></td><td><code>Char</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>#x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]</code></td><xsltdebug></xsltdebug><td><i>/* any Unicode character, excluding the surrogate blocks, FFFE, and FFFF. */</i></td></tr>
|
||
</tbody></table>
|
||
<p>The mechanism for encoding character code points into bit patterns may
|
||
vary from entity to entity. All XML processors must accept the UTF-8 and UTF-16
|
||
encodings of 10646; the mechanisms for signaling which of the two is in use,
|
||
or for bringing other encodings into play, are discussed later, in <a href="#charencoding"><b>4.3.3 Character Encoding in Entities</b></a>.</p>
|
||
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-common-syn"></a>2.3 Common Syntactic Constructs</h3>
|
||
<p>This section defines some symbols used widely in the grammar.</p>
|
||
<p><a href="#NT-S">S</a> (white space) consists of one or more space (#x20)
|
||
characters, carriage returns, line feeds, or tabs.</p>
|
||
|
||
<h5>White Space</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-S"></a>[3]<5D><><EFBFBD></td><td><code>S</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>(#x20 | #x9 | #xD | #xA)+</code></td><xsltdebug></xsltdebug></tr>
|
||
</tbody></table>
|
||
<p>Characters are classified for convenience as letters, digits, or other
|
||
characters. <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E30">[E30]</a>A
|
||
letter consists of an alphabetic or syllabic base character or an ideographic
|
||
character.</span> Full definitions of the specific characters in each class
|
||
are given in <a href="#CharClasses"><b>B Character Classes</b></a>.</p>
|
||
<p>[<a name="dt-name" title="Name">Definition</a>: A <b>Name</b> is a token beginning
|
||
with a letter or one of a few punctuation characters, and continuing with
|
||
letters, digits, hyphens, underscores, colons, or full stops, together known
|
||
as name characters.] Names beginning with the string "<code>xml</code>",
|
||
or any string which would match <code>(('X'|'x') ('M'|'m') ('L'|'l'))</code>,
|
||
are reserved for standardization in this or future versions of this specification.</p>
|
||
<div class="note"><p class="prefix"><b>Note:</b></p>
|
||
<div class="diff-chg"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E98">[E98]</a>The
|
||
Namespaces in XML Recommendation <a href="#xml-names">[XML Names]</a> assigns a meaning
|
||
to names containing colon characters. Therefore, authors should not use the
|
||
colon in XML names except for namespace purposes, but XML processors must
|
||
accept the colon as a name character.</p></div>
|
||
</div>
|
||
<p>An <a href="#NT-Nmtoken">Nmtoken</a> (name token) is any mixture of name
|
||
characters.</p>
|
||
|
||
<h5>Names and Tokens</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-NameChar"></a>[4]<5D><><EFBFBD></td><td><code>NameChar</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-Letter">Letter</a> | <a href="#NT-Digit">Digit</a>
|
||
| '.' | '-' | '_' | ':' | <a href="#NT-CombiningChar">CombiningChar</a> | <a href="#NT-Extender">Extender</a></code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-Name"></a>[5]<5D><><EFBFBD></td><td><code>Name</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>(<a href="#NT-Letter">Letter</a> | '_' | ':') (<a href="#NT-NameChar">NameChar</a>)*</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-Names"></a>[6]<5D><><EFBFBD></td><td><code>Names</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-Name">Name</a> (<a href="#NT-S">S</a> <a href="#NT-Name">Name</a>)*</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-Nmtoken"></a>[7]<5D><><EFBFBD></td><td><code>Nmtoken</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>(<a href="#NT-NameChar">NameChar</a>)+</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-Nmtokens"></a>[8]<5D><><EFBFBD></td><td><code>Nmtokens</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-Nmtoken">Nmtoken</a> (<a href="#NT-S">S</a> <a href="#NT-Nmtoken">Nmtoken</a>)*</code></td><xsltdebug></xsltdebug></tr></tbody></table>
|
||
<p>Literal data is any quoted string not containing the quotation mark used
|
||
as a delimiter for that string. Literals are used for specifying the content
|
||
of internal entities (<a href="#NT-EntityValue">EntityValue</a>), the values
|
||
of attributes (<a href="#NT-AttValue">AttValue</a>), and external identifiers
|
||
(<a href="#NT-SystemLiteral">SystemLiteral</a>). Note that a <a href="#NT-SystemLiteral">SystemLiteral</a>
|
||
can be parsed without scanning for markup.</p>
|
||
|
||
<h5>Literals</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-EntityValue"></a>[9]<5D><><EFBFBD></td><td><code>EntityValue</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'"' ([^%&"] | <a href="#NT-PEReference">PEReference</a>
|
||
| <a href="#NT-Reference">Reference</a>)* '"' </code></td><xsltdebug></xsltdebug></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>|<7C> "'" ([^%&'] | <a href="#NT-PEReference">PEReference</a> | <a href="#NT-Reference">Reference</a>)* "'"</code></td></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-AttValue"></a>[10]<5D><><EFBFBD></td><td><code>AttValue</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'"' ([^<&"] | <a href="#NT-Reference">Reference</a>)*
|
||
'"' </code></td><xsltdebug></xsltdebug></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>|<7C> "'" ([^<&'] | <a href="#NT-Reference">Reference</a>)*
|
||
"'"</code></td></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-SystemLiteral"></a>[11]<5D><><EFBFBD></td><td><code>SystemLiteral</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>('"' [^"]* '"') |<7C>("'" [^']* "'") </code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-PubidLiteral"></a>[12]<5D><><EFBFBD></td><td><code>PubidLiteral</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'"' <a href="#NT-PubidChar">PubidChar</a>* '"'
|
||
| "'" (<a href="#NT-PubidChar">PubidChar</a> - "'")* "'"</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-PubidChar"></a>[13]<5D><><EFBFBD></td><td><code>PubidChar</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>#x20 | #xD | #xA |<7C>[a-zA-Z0-9] |<7C>[-'()+,./:=?;!*#@$_%]</code></td><xsltdebug></xsltdebug></tr></tbody></table>
|
||
<div class="diff-add"><div class="note"><p class="prefix"><b>Note:</b></p>
|
||
<p><a href="http://www.w3.org/XML/xml-19980210-errata#E72">[E72]</a>Although
|
||
the <a href="#NT-EntityValue">EntityValue</a> production allows the definition
|
||
of an entity consisting of a single explicit <code><</code> in the literal
|
||
(e.g., <code><!ENTITY mylt "<"></code>), it is strongly advised to avoid
|
||
this practice since any reference to that entity will cause a well-formedness
|
||
error.</p>
|
||
</div></div>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="syntax"></a>2.4 Character Data and Markup</h3>
|
||
<p><a title="Text" href="#dt-text">Text</a> consists of intermingled <a title="Character Data" href="#dt-chardata">character data</a> and markup. [<a name="dt-markup" title="Markup">Definition</a>: <b>Markup</b> takes the form of <a title="Start-Tag" href="#dt-stag">start-tags</a>, <a title="End Tag" href="#dt-etag">end-tags</a>, <a title="Empty" href="#dt-empty">empty-element tags</a>, <a title="Entity Reference" href="#dt-entref">entity references</a>, <a title="Character Reference" href="#dt-charref">character
|
||
references</a>, <a title="Comment" href="#dt-comment">comments</a>, <a title="CDATA Section" href="#dt-cdsection">CDATA section</a> delimiters, <a title="Document Type Declaration" href="#dt-doctype">document
|
||
type declarations</a>, <a title="Processing instruction" href="#dt-pi">processing instructions</a>, <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E89">[E89]</a><a href="#NT-XMLDecl">XML declarations</a>, <a href="#NT-TextDecl">text declarations</a>,
|
||
and any white space that is at the top level of the document entity (that
|
||
is, outside the document element and not inside any other markup).</span>]</p>
|
||
<p>[<a name="dt-chardata" title="Character Data">Definition</a>: All text that is not markup
|
||
constitutes the <b>character data</b> of the document.]</p>
|
||
<p>The ampersand character (&) and the left angle bracket (<) may appear
|
||
in their literal form <em>only</em> when used as markup delimiters, or
|
||
within a <a title="Comment" href="#dt-comment">comment</a>, a <a title="Processing instruction" href="#dt-pi">processing
|
||
instruction</a>, or a <a title="CDATA Section" href="#dt-cdsection">CDATA section</a>.<span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E18">[E18]</a>They
|
||
are also legal within the <a title="Literal Entity Value" href="#dt-litentval">literal entity value</a>
|
||
of an internal entity declaration; see <a href="#wf-entities"><b>4.3.2 Well-Formed Parsed Entities</b></a>.</span>
|
||
If they are needed elsewhere, they must be <a title="escape" href="#dt-escape">escaped</a>
|
||
using either <a title="Character Reference" href="#dt-charref">numeric character references</a>
|
||
or the strings "<code>&amp;</code>" and "<code>&lt;</code>"
|
||
respectively. The right angle bracket (>) may be represented using the string "<code>&gt;</code>",
|
||
and must, <a title="For Compatibility" href="#dt-compat">for compatibility</a>, be escaped
|
||
using "<code>&gt;</code>" or a character reference when it
|
||
appears in the string "<code>]]></code>" in content, when
|
||
that string is not marking the end of a <a title="CDATA Section" href="#dt-cdsection">CDATA
|
||
section</a>.</p>
|
||
<p>In the content of elements, character data is any string of characters
|
||
which does not contain the start-delimiter of any markup. In a CDATA section,
|
||
character data is any string of characters not including the CDATA-section-close
|
||
delimiter, "<code>]]></code>".</p>
|
||
<p>To allow attribute values to contain both single and double quotes, the
|
||
apostrophe or single-quote character (') may be represented as "<code>&apos;</code>",
|
||
and the double-quote character (") as "<code>&quot;</code>".</p>
|
||
|
||
<h5>Character Data</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-CharData"></a>[14]<5D><><EFBFBD></td><td><code>CharData</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>[^<&]* - ([^<&]* ']]>' [^<&]*)</code></td><xsltdebug></xsltdebug></tr></tbody></table>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-comments"></a>2.5 Comments</h3>
|
||
<p>[<a name="dt-comment" title="Comment">Definition</a>: <b>Comments</b> may appear
|
||
anywhere in a document outside other <a title="Markup" href="#dt-markup">markup</a>;
|
||
in addition, they may appear within the document type declaration at places
|
||
allowed by the grammar. They are not part of the document's <a title="Character Data" href="#dt-chardata">character
|
||
data</a>; an XML processor may, but need not, make it possible for an
|
||
application to retrieve the text of comments. <a title="For Compatibility" href="#dt-compat">For
|
||
compatibility</a>, the string "<code>--</code>" (double-hyphen)
|
||
must not occur within comments.] <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E63">[E63]</a>Parameter
|
||
entity references are not recognized within comments.</span></p>
|
||
|
||
<h5>Comments</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-Comment"></a>[15]<5D><><EFBFBD></td><td><code>Comment</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<!--' ((<a href="#NT-Char">Char</a> - '-') | ('-'
|
||
(<a href="#NT-Char">Char</a> - '-')))* '-->'</code></td><xsltdebug></xsltdebug></tr></tbody></table>
|
||
<p>An example of a comment:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!-- declarations for <head> & <body> --></pre></td></tr></table>
|
||
<div class="diff-add"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E27">[E27]</a>Note
|
||
that the grammar does not allow a comment ending in <code>---></code>. The
|
||
following example is <em>not</em> well-formed.</p></div>
|
||
<div class="diff-add"><table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td class="diff-add"><pre><!-- B+, B, or B---></pre></td></tr></table></div>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-pi"></a>2.6 Processing Instructions</h3>
|
||
<p>[<a name="dt-pi" title="Processing instruction">Definition</a>: <b>Processing instructions</b>
|
||
(PIs) allow documents to contain instructions for applications.]</p>
|
||
|
||
<h5>Processing Instructions</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-PI"></a>[16]<5D><><EFBFBD></td><td><code>PI</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<?' <a href="#NT-PITarget">PITarget</a> (<a href="#NT-S">S</a>
|
||
(<a href="#NT-Char">Char</a>* - (<a href="#NT-Char">Char</a>* '?>' <a href="#NT-Char">Char</a>*)))? '?>'</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-PITarget"></a>[17]<5D><><EFBFBD></td><td><code>PITarget</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-Name">Name</a> - (('X' | 'x') ('M' |
|
||
'm') ('L' | 'l'))</code></td><xsltdebug></xsltdebug></tr></tbody></table>
|
||
<p>PIs are not part of the document's <a title="Character Data" href="#dt-chardata">character
|
||
data</a>, but must be passed through to the application. The PI begins
|
||
with a target (<a href="#NT-PITarget">PITarget</a>) used to identify the application
|
||
to which the instruction is directed. The target names "<code>XML</code>", "<code>xml</code>",
|
||
and so on are reserved for standardization in this or future versions of this
|
||
specification. The XML <a title="Notation" href="#dt-notation">Notation</a> mechanism
|
||
may be used for formal declaration of PI targets. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E63">[E63]</a>Parameter
|
||
entity references are not recognized within processing instructions.</span></p>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-cdata-sect"></a>2.7 CDATA Sections</h3>
|
||
<p>[<a name="dt-cdsection" title="CDATA Section">Definition</a>: <b>CDATA sections</b>
|
||
may occur anywhere character data may occur; they are used to escape blocks
|
||
of text containing characters which would otherwise be recognized as markup.
|
||
CDATA sections begin with the string "<code><![CDATA[</code>"
|
||
and end with the string "<code>]]></code>":]</p>
|
||
|
||
<h5>CDATA Sections</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-CDSect"></a>[18]<5D><><EFBFBD></td><td><code>CDSect</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-CDStart">CDStart</a> <a href="#NT-CData">CData</a> <a href="#NT-CDEnd">CDEnd</a></code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-CDStart"></a>[19]<5D><><EFBFBD></td><td><code>CDStart</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<![CDATA['</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-CData"></a>[20]<5D><><EFBFBD></td><td><code>CData</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>(<a href="#NT-Char">Char</a>* - (<a href="#NT-Char">Char</a>*
|
||
']]>' <a href="#NT-Char">Char</a>*)) </code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-CDEnd"></a>[21]<5D><><EFBFBD></td><td><code>CDEnd</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>']]>'</code></td><xsltdebug></xsltdebug></tr></tbody></table>
|
||
<p>Within a CDATA section, only the <a href="#NT-CDEnd">CDEnd</a> string is
|
||
recognized as markup, so that left angle brackets and ampersands may occur
|
||
in their literal form; they need not (and cannot) be escaped using "<code>&lt;</code>"
|
||
and "<code>&amp;</code>". CDATA sections cannot nest.</p>
|
||
<p>An example of a CDATA section, in which "<code><greeting></code>"
|
||
and "<code></greeting></code>" are recognized as <a title="Character Data" href="#dt-chardata">character data</a>, not <a title="Markup" href="#dt-markup">markup</a>:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><![CDATA[<greeting>Hello, world!</greeting>]]> </pre></td></tr></table>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-prolog-dtd"></a>2.8 Prolog and Document Type Declaration</h3>
|
||
<p>[<a name="dt-xmldecl" title="XML Declaration">Definition</a>: XML documents <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E107">[E107]</a>should</span>
|
||
begin with an <b>XML declaration</b> which specifies the version of
|
||
XML being used.] For example, the following is a complete XML document, <a title="Well-Formed" href="#dt-wellformed">well-formed</a> but not <a title="Validity" href="#dt-valid">valid</a>:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><?xml version="1.0"?> <greeting>Hello, world!</greeting> </pre></td></tr></table>
|
||
<p>and so is this:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><greeting>Hello, world!</greeting></pre></td></tr></table>
|
||
<p>The version number "<code>1.0</code>" should be used to indicate
|
||
conformance to this version of this specification; it is an error for a document
|
||
to use the value "<code>1.0</code>" if it does not conform to
|
||
this version of this specification. It is the intent of the XML working group
|
||
to give later versions of this specification numbers other than "<code>1.0</code>",
|
||
but this intent does not indicate a commitment to produce any future versions
|
||
of XML, nor if any are produced, to use any particular numbering scheme. Since
|
||
future versions are not ruled out, this construct is provided as a means to
|
||
allow the possibility of automatic version recognition, should it become necessary.
|
||
Processors may signal an error if they receive documents labeled with versions
|
||
they do not support.</p>
|
||
<p>The function of the markup in an XML document is to describe its storage
|
||
and logical structure and to associate attribute-value pairs with its logical
|
||
structures. XML provides a mechanism, the <a title="Document Type Declaration" href="#dt-doctype">document
|
||
type declaration</a>, to define constraints on the logical structure
|
||
and to support the use of predefined storage units. [<a name="dt-valid" title="Validity">Definition</a>: An XML document is <b>valid</b> if it has an associated
|
||
document type declaration and if the document complies with the constraints
|
||
expressed in it.]</p>
|
||
<p>The document type declaration must appear before the first <a title="Element" href="#dt-element">element</a>
|
||
in the document.</p>
|
||
|
||
<h5>Prolog</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-prolog"></a>[22]<5D><><EFBFBD></td><td><code>prolog</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-XMLDecl">XMLDecl</a>? <a href="#NT-Misc">Misc</a>*
|
||
(<a href="#NT-doctypedecl">doctypedecl</a> <a href="#NT-Misc">Misc</a>*)?</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-XMLDecl"></a>[23]<5D><><EFBFBD></td><td><code>XMLDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<?xml' <a href="#NT-VersionInfo">VersionInfo</a> <a href="#NT-EncodingDecl">EncodingDecl</a>? <a href="#NT-SDDecl">SDDecl</a>? <a href="#NT-S">S</a>? '?>'</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td class="diff-chg"><a name="NT-VersionInfo"></a>[24]<5D><><EFBFBD></td><td class="diff-chg"><code>VersionInfo</code></td><td class="diff-chg"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-chg"><code><a href="#NT-S">S</a> 'version' <a href="#NT-Eq">Eq</a>
|
||
("'" <a href="#NT-VersionNum">VersionNum</a> "'" | '"' <a href="#NT-VersionNum">VersionNum</a>
|
||
'"')<i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E15">[E15]</a> */</i></code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-Eq"></a>[25]<5D><><EFBFBD></td><td><code>Eq</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-S">S</a>? '=' <a href="#NT-S">S</a>?</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-VersionNum"></a>[26]<5D><><EFBFBD></td><td><code>VersionNum</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>([a-zA-Z0-9_.:] | '-')+</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-Misc"></a>[27]<5D><><EFBFBD></td><td><code>Misc</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-Comment">Comment</a> | <a href="#NT-PI">PI</a>
|
||
| <a href="#NT-S">S</a></code></td><xsltdebug></xsltdebug></tr>
|
||
</tbody></table>
|
||
<p>[<a name="dt-doctype" title="Document Type Declaration">Definition</a>: The XML <b>document
|
||
type declaration</b> contains or points to <a title="markup declaration" href="#dt-markupdecl">markup
|
||
declarations</a> that provide a grammar for a class of documents. This
|
||
grammar is known as a document type definition, or <b>DTD</b>. The document
|
||
type declaration can point to an external subset (a special kind of <a title="External Entity" href="#dt-extent">external entity</a>) containing markup declarations,
|
||
or can contain the markup declarations directly in an internal subset, or
|
||
can do both. The DTD for a document consists of both subsets taken together.]</p>
|
||
<p>[<a name="dt-markupdecl" title="markup declaration">Definition</a>: A <b>markup declaration</b>
|
||
is an <a title="Element Type declaration" href="#dt-eldecl">element type declaration</a>, an <a title="Attribute-List Declaration" href="#dt-attdecl">attribute-list declaration</a>, an <a title="entity declaration" href="#dt-entdecl">entity
|
||
declaration</a>, or a <a title="Notation Declaration" href="#dt-notdecl">notation declaration</a>.]
|
||
These declarations may be contained in whole or in part within <a title="Parameter entity" href="#dt-PE">parameter
|
||
entities</a>, as described in the well-formedness and validity constraints
|
||
below. For <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E14">[E14]</a>further</span>
|
||
information, see <a href="#sec-physical-struct"><b>4 Physical Structures</b></a>.</p>
|
||
|
||
<h5>Document Type Definition</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td class="diff-chg"><a name="NT-doctypedecl"></a>[28]<5D><><EFBFBD></td><td class="diff-chg"><code>doctypedecl</code></td><td class="diff-chg"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-chg"><code>'<!DOCTYPE' <a href="#NT-S">S</a> <a href="#NT-Name">Name</a>
|
||
(<a href="#NT-S">S</a> <a href="#NT-ExternalID">ExternalID</a>)? <a href="#NT-S">S</a>?
|
||
('[' (<a href="#NT-markupdecl">markupdecl</a> | <a href="#NT-DeclSep">DeclSep</a>)*
|
||
']' <a href="#NT-S">S</a>?)? '>'</code></td><xsltdebug></xsltdebug><td><a href="#vc-roottype">[VC: Root Element Type]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td class="diff-add"><a href="#ExtSubset">[WFC: External
|
||
Subset]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td class="diff-chg"><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</a> */</i></td></tr>
|
||
<tr valign="baseline"><td class="diff-add"><a name="NT-DeclSep"></a>[28a]<5D><><EFBFBD></td><td class="diff-add"><code>DeclSep</code></td><td class="diff-add"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-add"><code><a href="#NT-PEReference">PEReference</a> | <a href="#NT-S">S</a></code></td><xsltdebug></xsltdebug><td class="diff-add"><a href="#PE-between-Decls">[WFC: PE
|
||
Between Declarations]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td class="diff-add"><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</a> */</i></td></tr>
|
||
<tr valign="baseline"><td><a name="NT-markupdecl"></a>[29]<5D><><EFBFBD></td><td><code>markupdecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-elementdecl">elementdecl</a> | <a href="#NT-AttlistDecl">AttlistDecl</a> | <a href="#NT-EntityDecl">EntityDecl</a>
|
||
| <a href="#NT-NotationDecl">NotationDecl</a> | <a href="#NT-PI">PI</a> | <a href="#NT-Comment">Comment</a> </code></td><xsltdebug></xsltdebug><td><a href="#vc-PEinMarkupDecl">[VC: Proper Declaration/PE Nesting]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#wfc-PEinInternalSubset">[WFC: PEs in Internal Subset]</a></td></tr>
|
||
</tbody></table>
|
||
<div class="diff-add"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E82">[E82]</a>Note
|
||
that it is possible to construct a well-formed document containing a <a href="#NT-doctypedecl">doctypedecl</a>
|
||
that neither points to an external subset nor contains an internal subset.</p></div>
|
||
<p>The markup declarations may be made up in whole or in part of the <a title="Replacement Text" href="#dt-repltext">replacement text</a> of <a title="Parameter entity" href="#dt-PE">parameter
|
||
entities</a>. The productions later in this specification for individual
|
||
nonterminals (<a href="#NT-elementdecl">elementdecl</a>, <a href="#NT-AttlistDecl">AttlistDecl</a>,
|
||
and so on) describe the declarations <em>after</em> all the parameter
|
||
entities have been <a title="Include" href="#dt-include">included</a>.</p>
|
||
<div class="diff-add"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E75">[E75]</a>Parameter
|
||
entity references are recognized anywhere in the DTD (internal and external
|
||
subsets and external parameter entities), except in literals, processing instructions,
|
||
comments, and the contents of ignored conditional sections (see <a href="#sec-condition-sect"><b>3.4 Conditional Sections</b></a>).
|
||
They are also recognized in entity value literals. The use of parameter entities
|
||
in the internal subset is restricted as described below.</p></div>
|
||
<div class="constraint"><p class="prefix"><a name="vc-roottype"></a><b>Validity constraint: Root Element Type</b></p><p>The <a href="#NT-Name">Name</a>
|
||
in the document type declaration must match the element type of the <a title="Root Element" href="#dt-root">root element</a>.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="vc-PEinMarkupDecl"></a><b>Validity constraint: Proper Declaration/PE Nesting</b></p>
|
||
<p>Parameter-entity <a title="Replacement Text" href="#dt-repltext">replacement text</a>
|
||
must be properly nested with markup declarations. That is to say, if either
|
||
the first character or the last character of a markup declaration (<a href="#NT-markupdecl">markupdecl</a>
|
||
above) is contained in the replacement text for a <a title="Parameter-entity reference" href="#dt-PERef">parameter-entity
|
||
reference</a>, both must be contained in the same replacement text.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="wfc-PEinInternalSubset"></a><b>Well-formedness constraint: PEs in Internal Subset</b></p><p>In
|
||
the internal DTD subset, <a title="Parameter-entity reference" href="#dt-PERef">parameter-entity references</a>
|
||
can occur only where markup declarations can occur, not within markup declarations.
|
||
(This does not apply to references that occur in external parameter entities
|
||
or to the external subset.)</p>
|
||
</div>
|
||
<div class="diff-add"><div class="constraint"><p class="prefix"><a name="ExtSubset"></a><b>Well-formedness constraint: <a href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</a>External
|
||
Subset</b></p><p>The external subset, if any, must match the production for <a href="#NT-extSubset">extSubset</a>.</p>
|
||
</div></div>
|
||
<div class="diff-add"><div class="constraint"><p class="prefix"><a name="PE-between-Decls"></a><b>Well-formedness constraint: <a href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</a>PE
|
||
Between Declarations</b></p><p>The replacement text of a parameter entity reference
|
||
in a <a href="#NT-DeclSep">DeclSep</a> must match the production <a href="#NT-extSubsetDecl">extSubsetDecl</a>.</p>
|
||
</div></div>
|
||
<p>Like the internal subset, the external subset and any external parameter
|
||
entities <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</a>referenced
|
||
in a <a href="#NT-DeclSep">DeclSep</a></span> must consist of a series of
|
||
complete markup declarations of the types allowed by the non-terminal symbol <a href="#NT-markupdecl">markupdecl</a>, interspersed with white space or <a title="Parameter-entity reference" href="#dt-PERef">parameter-entity references</a>. However, portions of
|
||
the contents of the external subset or of <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</a>these </span>
|
||
external parameter entities may conditionally be ignored by using the <a title="conditional section" href="#dt-cond-section">conditional section</a> construct; this is not
|
||
allowed in the internal subset.</p>
|
||
|
||
<h5>External Subset</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-extSubset"></a>[30]<5D><><EFBFBD></td><td><code>extSubset</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-TextDecl">TextDecl</a>? <a href="#NT-extSubsetDecl">extSubsetDecl</a></code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td class="diff-chg"><a name="NT-extSubsetDecl"></a>[31]<5D><><EFBFBD></td><td class="diff-chg"><code>extSubsetDecl</code></td><td class="diff-chg"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-chg"><code>( <a href="#NT-markupdecl">markupdecl</a> | <a href="#NT-conditionalSect">conditionalSect</a> | <a href="#NT-DeclSep">DeclSep</a>)*</code></td><xsltdebug></xsltdebug><td class="diff-chg"><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</a> */</i></td></tr>
|
||
</tbody></table>
|
||
<p>The external subset and external parameter entities also differ from the
|
||
internal subset in that in them, <a title="Parameter-entity reference" href="#dt-PERef">parameter-entity
|
||
references</a> are permitted <em>within</em> markup declarations,
|
||
not only <em>between</em> markup declarations.</p>
|
||
<p>An example of an XML document with a document type declaration:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><?xml version="1.0"?> <!DOCTYPE greeting SYSTEM "hello.dtd"> <greeting>Hello, world!</greeting> </pre></td></tr></table>
|
||
<p>The <a title="System Identifier" href="#dt-sysid">system identifier</a> "<code>hello.dtd</code>"
|
||
gives the <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E78">[E78]</a>address
|
||
(a URI reference)</span> of a DTD for the document.</p>
|
||
<p>The declarations can also be given locally, as in this example:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><?xml version="1.0" encoding="UTF-8" ?>
|
||
<!DOCTYPE greeting [
|
||
<!ELEMENT greeting (#PCDATA)>
|
||
]>
|
||
<greeting>Hello, world!</greeting></pre></td></tr></table>
|
||
<p>If both the external and internal subsets are used, the internal subset
|
||
is considered to occur before the external subset.
|
||
This has the effect that entity and attribute-list declarations in the internal
|
||
subset take precedence over those in the external subset.</p>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-rmd"></a>2.9 Standalone Document Declaration</h3>
|
||
<p>Markup declarations can affect the content of the document, as passed from
|
||
an <a title="XML Processor" href="#dt-xml-proc">XML processor</a> to an application; examples
|
||
are attribute defaults and entity declarations. The standalone document declaration,
|
||
which may appear as a component of the XML declaration, signals whether or
|
||
not there are such declarations which appear external to the <a title="Document Entity" href="#dt-docent">document
|
||
entity</a><span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E64">[E64]</a>
|
||
or in parameter entities. [<a name="dt-extmkpdecl" title="External Markup Declaration">Definition</a>: An <b>external
|
||
markup declaration</b> is defined as a markup declaration occurring in
|
||
the external subset or in a parameter entity (external or internal, the latter
|
||
being included because non-validating processors are not required to read
|
||
them).]</span></p>
|
||
|
||
<h5>Standalone Document Declaration</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-SDDecl"></a>[32]<5D><><EFBFBD></td><td><code>SDDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code> <a href="#NT-S">S</a> 'standalone' <a href="#NT-Eq">Eq</a>
|
||
(("'" ('yes' | 'no') "'") | ('"' ('yes' | 'no') '"')) </code></td><xsltdebug></xsltdebug><td><a href="#vc-check-rmd">[VC: Standalone Document Declaration]</a></td></tr>
|
||
</tbody></table>
|
||
<p>In a standalone document declaration, the value "yes" indicates
|
||
that there are no <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E64">[E64]</a><a title="External Markup Declaration" href="#dt-extmkpdecl">external markup declarations</a></span> which
|
||
affect the information passed from the XML processor to the application. The
|
||
value "no" indicates that there are or may be such external
|
||
markup declarations. Note that the standalone document declaration only denotes
|
||
the presence of external <em>declarations</em>; the presence, in a document,
|
||
of references to external <em>entities</em>, when those entities are internally
|
||
declared, does not change its standalone status.</p>
|
||
<p>If there are no external markup declarations, the standalone document declaration
|
||
has no meaning. If there are external markup declarations but there is no
|
||
standalone document declaration, the value "no" is assumed.</p>
|
||
<p>Any XML document for which <code>standalone="no"</code> holds can be converted
|
||
algorithmically to a standalone document, which may be desirable for some
|
||
network delivery applications.</p>
|
||
<div class="constraint"><p class="prefix"><a name="vc-check-rmd"></a><b>Validity constraint: Standalone Document Declaration</b></p><p>The
|
||
standalone document declaration must have the value "no" if
|
||
any external markup declarations contain declarations of:</p>
|
||
<ul>
|
||
<li><p>attributes with <a title="Attribute Default" href="#dt-default">default</a> values,
|
||
if elements to which these attributes apply appear in the document without
|
||
specifications of values for these attributes, or</p></li>
|
||
<li><p>entities (other than <code>amp</code>,
|
||
<code>lt</code>,
|
||
<code>gt</code>,
|
||
<code>apos</code>,
|
||
<code>quot</code>), if <a title="Entity Reference" href="#dt-entref">references</a>
|
||
to those entities appear in the document, or</p></li>
|
||
<li><p>attributes with values subject to <a href="#AVNormalize"><cite>normalization</cite></a>,
|
||
where the attribute appears in the document with a value which will change
|
||
as a result of normalization, or</p></li>
|
||
<li><p>element types with <a title="Element content" href="#dt-elemcontent">element content</a>,
|
||
if white space occurs directly within any instance of those types.</p></li>
|
||
</ul>
|
||
</div>
|
||
<p>An example XML declaration with a standalone document declaration:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><?xml version="1.0" standalone='yes'?></pre></td></tr></table>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-white-space"></a>2.10 White Space Handling</h3>
|
||
<p>In editing XML documents, it is often convenient to use "white space"
|
||
(spaces, tabs, and blank lines<span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E39">[E39]</a>,
|
||
denoted by the nonterminal <a href="#NT-S">S</a> in this specification</span>)
|
||
to set apart the markup for greater readability. Such white space is typically
|
||
not intended for inclusion in the delivered version of the document. On the
|
||
other hand, "significant" white space that should be preserved
|
||
in the delivered version is common, for example in poetry and source code.</p>
|
||
<p>An <a title="XML Processor" href="#dt-xml-proc">XML processor</a> must always pass
|
||
all characters in a document that are not markup through to the application.
|
||
A <a title="Validating Processor" href="#dt-validating"> validating XML processor</a> must also
|
||
inform the application which of these characters constitute white space appearing
|
||
in <a title="Element content" href="#dt-elemcontent">element content</a>.</p>
|
||
<p>A special <a title="Attribute" href="#dt-attr">attribute</a> named <code>xml:space</code>
|
||
may be attached to an element to signal an intention that in that element,
|
||
white space should be preserved by applications. In valid documents, this
|
||
attribute, like any other, must be <a title="Attribute-List Declaration" href="#dt-attdecl">declared</a>
|
||
if it is used. When declared, it must be given as an <a title="Enumerated Attribute Values" href="#dt-enumerated">enumerated
|
||
type</a> whose <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E81">[E81]</a>values
|
||
are one or both of</span> "default" and "preserve".
|
||
For example:</p>
|
||
<div class="diff-chg"><table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td class="diff-chg"><pre><!ATTLIST poem xml:space (default|preserve) 'preserve'>
|
||
|
||
<!-- <a href="http://www.w3.org/XML/xml-19980210-errata#E81">[E81]</a>-->
|
||
<!ATTLIST pre xml:space (preserve) #FIXED 'preserve'></pre></td></tr></table></div>
|
||
<p>The value "default" signals that applications' default white-space
|
||
processing modes are acceptable for this element; the value "preserve"
|
||
indicates the intent that applications preserve all the white space. This
|
||
declared intent is considered to apply to all elements within the content
|
||
of the element where it is specified, unless overriden with another instance
|
||
of the <code>xml:space</code> attribute.</p>
|
||
<p>The <a title="Root Element" href="#dt-root">root element</a> of any document is considered
|
||
to have signaled no intentions as regards application space handling, unless
|
||
it provides a value for this attribute or the attribute is declared with a
|
||
default value.</p>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-line-ends"></a>2.11 End-of-Line Handling</h3>
|
||
<p>XML <a title="Text Entity" href="#dt-parsedent">parsed entities</a> are often stored
|
||
in computer files which, for editing convenience, are organized into lines.
|
||
These lines are typically separated by some combination of the characters
|
||
carriage-return (#xD) and line-feed (#xA).</p>
|
||
<div class="diff-del"><p>To simplify the tasks of <a title="Application" href="#dt-app">applications</a>,
|
||
wherever an external parsed entity or the literal entity value of an internal
|
||
parsed entity contains either the literal two-character sequence "#xD#xA"
|
||
or a standalone literal #xD, an <a title="XML Processor" href="#dt-xml-proc">XML processor</a>
|
||
must pass to the application the single character #xA. (This behavior can
|
||
conveniently be produced by normalizing all line breaks to #xA on input, before
|
||
parsing.)</p></div>
|
||
<div class="diff-add"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E104">[E104]</a>To
|
||
simplify the tasks of <a title="Application" href="#dt-app">applications</a>, the characters
|
||
passed to an application by the <a title="XML Processor" href="#dt-xml-proc">XML processor</a>
|
||
must be as if the XML processor normalized all line breaks in external parsed
|
||
entities (including the document entity) on input, before parsing, by translating
|
||
both the two-character sequence #xD #xA and any #xD that is not followed by
|
||
#xA to a single #xA character.</p></div>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-lang-tag"></a>2.12 Language Identification</h3>
|
||
<p>In document processing, it is often useful to identify the natural or formal
|
||
language in which the content is written. A special <a title="Attribute" href="#dt-attr">attribute</a>
|
||
named <code>xml:lang</code> may be inserted in documents to specify the language
|
||
used in the contents and attribute values of any element in an XML document.
|
||
In valid documents, this attribute, like any other, must be <a title="Attribute-List Declaration" href="#dt-attdecl">declared</a>
|
||
if it is used. <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E73">[E73]</a>The
|
||
values of the attribute are language identifiers as defined by <a href="#RFC1766">[IETF RFC 1766]</a>, <cite>Tags
|
||
for the Identification of Languages</cite>, or its successor on the IETF
|
||
Standards Track.</span></p>
|
||
<div class="diff-add"><div class="note"><p class="prefix"><b>Note:</b></p>
|
||
<p><a href="http://www.w3.org/XML/xml-19980210-errata#E73">[E73]</a><a href="#RFC1766">[IETF RFC 1766]</a> tags are constructed from two-letter language codes as defined
|
||
by <a href="#ISO639">[ISO 639]</a>, from two-letter country codes as defined by <a href="#ISO3166">[ISO 3166]</a>, or from language identifiers registered with the Internet
|
||
Assigned Numbers Authority <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E58">[E58]</a><span class="diff-chg"><a href="#IANA-LANGCODES">[IANA-LANGCODES]</a></span></span>. It is expected that the successor
|
||
to <a href="#RFC1766">[IETF RFC 1766]</a> will introduce three-letter language codes for
|
||
languages not presently covered by <a href="#ISO639">[ISO 639]</a>.</p>
|
||
</div></div>
|
||
<div class="diff-add"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E73">[E73]</a>(Productions
|
||
33 through 38 have been removed.)</p></div>
|
||
<div class="diff-del">
|
||
<h5>Language Identification</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td class="diff-del"><a name="NT-LanguageID"></a>[33]<5D><><EFBFBD></td><td class="diff-del"><code>LanguageID</code></td><td class="diff-del"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-del"><code><a href="#NT-Langcode">Langcode</a> ('-' <a href="#NT-Subcode">Subcode</a>)*</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td class="diff-del"><a name="NT-Langcode"></a>[34]<5D><><EFBFBD></td><td class="diff-del"><code>Langcode</code></td><td class="diff-del"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-del"><code><a href="#NT-ISO639Code">ISO639Code</a> | <a href="#NT-IanaCode">IanaCode</a>
|
||
| <a href="#NT-UserCode">UserCode</a></code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td class="diff-del"><a name="NT-ISO639Code"></a>[35]<5D><><EFBFBD></td><td class="diff-del"><code>ISO639Code</code></td><td class="diff-del"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-del"><code>([a-z] | [A-Z]) ([a-z] | [A-Z])</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td class="diff-del"><a name="NT-IanaCode"></a>[36]<5D><><EFBFBD></td><td class="diff-del"><code>IanaCode</code></td><td class="diff-del"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-del"><code>('i' | 'I') '-' ([a-z] | [A-Z])+</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td class="diff-del"><a name="NT-UserCode"></a>[37]<5D><><EFBFBD></td><td class="diff-del"><code>UserCode</code></td><td class="diff-del"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-del"><code>('x' | 'X') '-' ([a-z] | [A-Z])+</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td class="diff-del"><a name="NT-Subcode"></a>[38]<5D><><EFBFBD></td><td class="diff-del"><code>Subcode</code></td><td class="diff-del"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-del"><code>([a-z] | [A-Z])+</code></td><xsltdebug></xsltdebug></tr></tbody></table></div>
|
||
<div class="diff-del"><p>The <a href="#NT-Langcode">Langcode</a> may be any of the following:</p></div>
|
||
<div class="diff-del"><ul>
|
||
<li><p>a two-letter language code as defined by <a href="#ISO639">[ISO 639]</a>, <cite>Codes
|
||
for the representation of names of languages</cite></p></li>
|
||
<li><p>a language identifier registered with the Internet Assigned Numbers
|
||
Authority <span class="diff-chg"><a href="#IANA-LANGCODES">[IANA-LANGCODES]</a></span>; these begin with the
|
||
prefix "<code>i-</code>" (or "<code>I-</code>")</p>
|
||
</li>
|
||
<li><p>a language identifier assigned by the user, or agreed on between
|
||
parties in private use; these must begin with the prefix "<code>x-</code>"
|
||
or "<code>X-</code>" in order to ensure that they do not conflict
|
||
with names later standardized or registered with IANA</p></li>
|
||
</ul></div>
|
||
<div class="diff-del"><p>There may be any number of <a href="#NT-Subcode">Subcode</a>
|
||
segments; if the first subcode segment exists and the Subcode consists of
|
||
two letters, then it must be a country code from <a href="#ISO3166">[ISO 3166]</a>,
|
||
"Codes for the representation of names of countries." If the first subcode
|
||
consists of more than two letters, it must be a subcode for the language in
|
||
question registered with IANA, unless the <a href="#NT-Langcode">Langcode</a>
|
||
begins with the prefix "<code>x-</code>" or "<code>X-</code>". </p></div>
|
||
<div class="diff-del"><p>It is customary to give the language code in lower case, and
|
||
the country code (if any) in upper case. Note that these values, unlike other
|
||
names in XML documents, are case insensitive.</p></div>
|
||
<p>For example:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><p xml:lang="en">The quick brown fox jumps over the lazy dog.</p>
|
||
<p xml:lang="en-GB">What colour is it?</p>
|
||
<p xml:lang="en-US">What color is it?</p>
|
||
<sp who="Faust" desc='leise' xml:lang="de">
|
||
<l>Habe nun, ach! Philosophie,</l>
|
||
<l>Juristerei, und Medizin</l>
|
||
<l>und leider auch Theologie</l>
|
||
<l>durchaus studiert mit hei<65>em Bem<65>h'n.</l>
|
||
</sp></pre></td></tr></table>
|
||
|
||
<p>The intent declared with <code>xml:lang</code> is considered to apply to
|
||
all attributes and content of the element where it is specified, unless overridden
|
||
with an instance of <code>xml:lang</code> on another element within that content.</p>
|
||
|
||
<p>A simple declaration for <code>xml:lang</code> might take the form</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre>xml:lang NMTOKEN #IMPLIED</pre></td></tr></table>
|
||
<p>but specific default values may also be given, if appropriate. In a collection
|
||
of French poems for English students, with glosses and notes in English, the <code>xml:lang</code>
|
||
attribute might be declared this way:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ATTLIST poem xml:lang NMTOKEN 'fr'>
|
||
<!ATTLIST gloss xml:lang NMTOKEN 'en'>
|
||
<!ATTLIST note xml:lang NMTOKEN 'en'></pre></td></tr></table>
|
||
</div>
|
||
</div>
|
||
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-logical-struct"></a>3 Logical Structures</h2>
|
||
<p>[<a name="dt-element" title="Element">Definition</a>: Each <a title="XML Document" href="#dt-xml-doc">XML
|
||
document</a> contains one or more <b>elements</b>, the boundaries
|
||
of which are either delimited by <a title="Start-Tag" href="#dt-stag">start-tags</a>
|
||
and <a title="End Tag" href="#dt-etag">end-tags</a>, or, for <a title="Empty" href="#dt-empty">empty</a>
|
||
elements, by an <a title="empty-element tag" href="#dt-eetag">empty-element tag</a>. Each
|
||
element has a type, identified by name, sometimes called its "generic
|
||
identifier" (GI), and may have a set of attribute specifications.]
|
||
Each attribute specification has a <a title="Attribute Name" href="#dt-attrname">name</a>
|
||
and a <a title="Attribute Value" href="#dt-attrval">value</a>.</p>
|
||
|
||
<h5>Element</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-element"></a>[39]<5D><><EFBFBD></td><td><code>element</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-EmptyElemTag">EmptyElemTag</a></code></td><xsltdebug></xsltdebug></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| <a href="#NT-STag">STag</a> <a href="#NT-content">content</a> <a href="#NT-ETag">ETag</a></code></td><td><a href="#GIMatch">[WFC: Element Type Match]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#elementvalid">[VC: Element Valid]</a></td></tr></tbody></table>
|
||
<p>This specification does not constrain the semantics, use, or (beyond syntax)
|
||
names of the element types and attributes, except that names beginning with
|
||
a match to <code>(('X'|'x')('M'|'m')('L'|'l'))</code> are reserved for standardization
|
||
in this or future versions of this specification.</p>
|
||
<div class="constraint"><p class="prefix"><a name="GIMatch"></a><b>Well-formedness constraint: Element Type Match</b></p><p>The <a href="#NT-Name">Name</a>
|
||
in an element's end-tag must match the element type in the start-tag.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="elementvalid"></a><b>Validity constraint: Element Valid</b></p><p>An element is valid
|
||
if there is a declaration matching <a href="#NT-elementdecl">elementdecl</a>
|
||
where the <a href="#NT-Name">Name</a> matches the element type, and one of
|
||
the following holds:</p>
|
||
<ol>
|
||
<li><p>The declaration matches <b>EMPTY</b> and the element has no <a title="Content" href="#dt-content">content</a>.</p></li>
|
||
<li><p>The declaration matches <a href="#NT-children">children</a> and the
|
||
sequence of <a title="Parent/Child" href="#dt-parentchild">child elements</a> belongs
|
||
to the language generated by the regular expression in the content model,
|
||
with optional white space (characters matching the nonterminal <a href="#NT-S">S</a>)
|
||
between <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E59">[E59]</a>the
|
||
start-tag and the first child element, between child elements, or between
|
||
the last child element and the end-tag. Note that a CDATA section containing
|
||
only white space does not match the nonterminal <a href="#NT-S">S</a>, and
|
||
hence cannot appear in these positions.</span></p></li>
|
||
<li><p>The declaration matches <a href="#NT-Mixed">Mixed</a> and the content
|
||
consists of <a title="Character Data" href="#dt-chardata">character data</a> and <a title="Parent/Child" href="#dt-parentchild">child elements</a> whose types match names in the
|
||
content model.</p></li>
|
||
<li><p>The declaration matches <b>ANY</b>, and the types of any <a title="Parent/Child" href="#dt-parentchild">child elements</a> have been declared.</p></li>
|
||
</ol>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-starttags"></a>3.1 Start-Tags, End-Tags, and Empty-Element Tags</h3>
|
||
<p>[<a name="dt-stag" title="Start-Tag">Definition</a>: The beginning of every non-empty
|
||
XML element is marked by a <b>start-tag</b>.]</p>
|
||
|
||
<h5>Start-tag</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-STag"></a>[40]<5D><><EFBFBD></td><td><code>STag</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<' <a href="#NT-Name">Name</a> (<a href="#NT-S">S</a> <a href="#NT-Attribute">Attribute</a>)* <a href="#NT-S">S</a>? '>'</code></td><xsltdebug></xsltdebug><td><a href="#uniqattspec">[WFC: Unique Att Spec]</a></td></tr>
|
||
<tr valign="baseline"><td><a name="NT-Attribute"></a>[41]<5D><><EFBFBD></td><td><code>Attribute</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-Name">Name</a> <a href="#NT-Eq">Eq</a> <a href="#NT-AttValue">AttValue</a></code></td><xsltdebug></xsltdebug><td><a href="#ValueType">[VC: Attribute Value Type]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#NoExternalRefs">[WFC: No External Entity References]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#CleanAttrVals">[WFC: No < in Attribute Values]</a></td></tr>
|
||
</tbody></table>
|
||
<p>The <a href="#NT-Name">Name</a> in the start- and end-tags gives the element's <b>type</b>. [<a name="dt-attr" title="Attribute">Definition</a>: The <a href="#NT-Name">Name</a>-<a href="#NT-AttValue">AttValue</a>
|
||
pairs are referred to as the <b>attribute specifications</b> of the
|
||
element], [<a name="dt-attrname" title="Attribute Name">Definition</a>: with the <a href="#NT-Name">Name</a> in each pair referred to as the <b>attribute name</b>]
|
||
and [<a name="dt-attrval" title="Attribute Value">Definition</a>: the content of the <a href="#NT-AttValue">AttValue</a> (the text between the <code>'</code> or <code>"</code>
|
||
delimiters) as the <b>attribute value</b>.]<span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E46">[E46]</a>Note
|
||
that the order of attribute specifications in a start-tag or empty-element
|
||
tag is not significant.</span></p>
|
||
<div class="constraint"><p class="prefix"><a name="uniqattspec"></a><b>Well-formedness constraint: Unique Att Spec</b></p><p>No attribute name
|
||
may appear more than once in the same start-tag or empty-element tag.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="ValueType"></a><b>Validity constraint: Attribute Value Type</b></p><p>The attribute must
|
||
have been declared; the value must be of the type declared for it. (For attribute
|
||
types, see <a href="#attdecls"><b>3.3 Attribute-List Declarations</b></a>.)</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="NoExternalRefs"></a><b>Well-formedness constraint: No External Entity References</b></p><p>Attribute
|
||
values cannot contain direct or indirect entity references to external entities.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="CleanAttrVals"></a><b>Well-formedness constraint: No <code><</code> in Attribute Values</b></p>
|
||
<p>The <a title="Replacement Text" href="#dt-repltext">replacement text</a> of any entity
|
||
referred to directly or indirectly in an attribute value <span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E83">[E83]</a>(other
|
||
than "<code>&lt;</code>") </span>must not contain a <code><</code>.</p>
|
||
</div>
|
||
<p>An example of a start-tag:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><termdef id="dt-dog" term="dog"></pre></td></tr></table>
|
||
<p>[<a name="dt-etag" title="End Tag">Definition</a>: The end of every element that begins
|
||
with a start-tag must be marked by an <b>end-tag</b> containing a name
|
||
that echoes the element's type as given in the start-tag:]</p>
|
||
|
||
<h5>End-tag</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-ETag"></a>[42]<5D><><EFBFBD></td><td><code>ETag</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'</' <a href="#NT-Name">Name</a> <a href="#NT-S">S</a>?
|
||
'>'</code></td><xsltdebug></xsltdebug></tr>
|
||
</tbody></table>
|
||
<p>An example of an end-tag:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre></termdef></pre></td></tr></table>
|
||
<p>[<a name="dt-content" title="Content">Definition</a>: The <a title="Text" href="#dt-text">text</a>
|
||
between the start-tag and end-tag is called the element's <b>content</b>:]</p>
|
||
|
||
<h5>Content of Elements</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td class="diff-chg"><a name="NT-content"></a>[43]<5D><><EFBFBD></td><td class="diff-chg"><code>content</code></td><td class="diff-chg"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-chg"><code><a href="#NT-CharData">CharData</a>? ((<a href="#NT-element">element</a>
|
||
| <a href="#NT-Reference">Reference</a> | <a href="#NT-CDSect">CDSect</a>
|
||
| <a href="#NT-PI">PI</a> | <a href="#NT-Comment">Comment</a>) <a href="#NT-CharData">CharData</a>?)*</code></td><xsltdebug></xsltdebug><td class="diff-chg"><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E71">[E71]</a> */</i></td></tr>
|
||
</tbody></table>
|
||
<p><span class="diff-chg">[<a name="dt-empty" title="Empty">Definition</a>: <a href="http://www.w3.org/XML/xml-19980210-errata#E97">[E97]</a>An element
|
||
with no content is said to be <b>empty</b>.] The representation
|
||
of an empty element is either a start-tag immediately followed by an end-tag,
|
||
or an empty-element tag.</span> [<a name="dt-eetag" title="empty-element tag">Definition</a>: An <b>empty-element
|
||
tag</b> takes a special form:]</p>
|
||
|
||
<h5>Tags for Empty Elements</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-EmptyElemTag"></a>[44]<5D><><EFBFBD></td><td><code>EmptyElemTag</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<' <a href="#NT-Name">Name</a> (<a href="#NT-S">S</a> <a href="#NT-Attribute">Attribute</a>)* <a href="#NT-S">S</a>? '/>'</code></td><xsltdebug></xsltdebug><td><a href="#uniqattspec">[WFC: Unique Att Spec]</a></td></tr>
|
||
</tbody></table>
|
||
<p>Empty-element tags may be used for any element which has no content, whether
|
||
or not it is declared using the keyword <b>EMPTY</b>. <a title="For interoperability" href="#dt-interop">For
|
||
interoperability</a>, the empty-element tag <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E45">[E45]</a>should
|
||
be used, and should only be used,</span> for elements which are declared
|
||
EMPTY.</p>
|
||
<p>Examples of empty elements:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><IMG align="left"
|
||
src="http://www.w3.org/Icons/WWW/w3c_home" />
|
||
<br></br>
|
||
<br/></pre></td></tr></table>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="elemdecls"></a>3.2 Element Type Declarations</h3>
|
||
<p>The <a title="Element" href="#dt-element">element</a> structure of an <a title="XML Document" href="#dt-xml-doc">XML document</a> may, for <a title="Validity" href="#dt-valid">validation</a>
|
||
purposes, be constrained using element type and attribute-list declarations.
|
||
An element type declaration constrains the element's <a title="Content" href="#dt-content">content</a>.</p>
|
||
<p>Element type declarations often constrain which element types can appear
|
||
as <a title="Parent/Child" href="#dt-parentchild">children</a> of the element. At user
|
||
option, an XML processor may issue a warning when a declaration mentions an
|
||
element type for which no declaration is provided, but this is not an error.</p>
|
||
<p>[<a name="dt-eldecl" title="Element Type declaration">Definition</a>: An <b>element
|
||
type declaration</b> takes the form:]</p>
|
||
|
||
<h5>Element Type Declaration</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-elementdecl"></a>[45]<5D><><EFBFBD></td><td><code>elementdecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<!ELEMENT' <a href="#NT-S">S</a> <a href="#NT-Name">Name</a> <a href="#NT-S">S</a> <a href="#NT-contentspec">contentspec</a> <a href="#NT-S">S</a>?
|
||
'>'</code></td><xsltdebug></xsltdebug><td><a href="#EDUnique">[VC: Unique Element Type Declaration]</a></td></tr>
|
||
<tr valign="baseline"><td><a name="NT-contentspec"></a>[46]<5D><><EFBFBD></td><td><code>contentspec</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'EMPTY' | 'ANY' | <a href="#NT-Mixed">Mixed</a>
|
||
| <a href="#NT-children">children</a> </code></td><xsltdebug></xsltdebug></tr>
|
||
</tbody></table>
|
||
<p>where the <a href="#NT-Name">Name</a> gives the element type being declared.</p>
|
||
<div class="constraint"><p class="prefix"><a name="EDUnique"></a><b>Validity constraint: Unique Element Type Declaration</b></p><p>No element
|
||
type may be declared more than once.</p>
|
||
</div>
|
||
<p>Examples of element type declarations:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ELEMENT br EMPTY>
|
||
<!ELEMENT p (#PCDATA|emph)* >
|
||
<!ELEMENT %name.para; %content.para; >
|
||
<!ELEMENT container ANY></pre></td></tr></table>
|
||
<div class="div3">
|
||
|
||
<h4><a name="sec-element-content"></a>3.2.1 Element Content</h4>
|
||
<p>[<a name="dt-elemcontent" title="Element content">Definition</a>: An element <a title="Start-Tag" href="#dt-stag">type</a> has <b>element content</b> when elements
|
||
of that type must contain only <a title="Parent/Child" href="#dt-parentchild">child</a>
|
||
elements (no character data), optionally separated by white space (characters
|
||
matching the nonterminal <a href="#NT-S">S</a>).][<a name="dt-content-model" title="Content model">Definition</a>: In this case, the constraint includes a <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E55">[E55]</a><b>content
|
||
model</b></span>, a simple grammar governing the allowed types of the
|
||
child elements and the order in which they are allowed to appear.]
|
||
The grammar is built on content particles (<a href="#NT-cp">cp</a>s), which
|
||
consist of names, choice lists of content particles, or sequence lists of
|
||
content particles:</p>
|
||
|
||
<h5>Element-content Models</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-children"></a>[47]<5D><><EFBFBD></td><td><code>children</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>(<a href="#NT-choice">choice</a> | <a href="#NT-seq">seq</a>)
|
||
('?' | '*' | '+')?</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-cp"></a>[48]<5D><><EFBFBD></td><td><code>cp</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>(<a href="#NT-Name">Name</a> | <a href="#NT-choice">choice</a>
|
||
| <a href="#NT-seq">seq</a>) ('?' | '*' | '+')?</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td class="diff-chg"><a name="NT-choice"></a>[49]<5D><><EFBFBD></td><td class="diff-chg"><code>choice</code></td><td class="diff-chg"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-chg"><code>'(' <a href="#NT-S">S</a>? <a href="#NT-cp">cp</a> ( <a href="#NT-S">S</a>? '|' <a href="#NT-S">S</a>? <a href="#NT-cp">cp</a> )+ <a href="#NT-S">S</a>? ')'</code></td><xsltdebug></xsltdebug><td class="diff-chg"><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E50">[E50]</a> */</i></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td class="diff-chg"><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E52">[E52]</a> */</i></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#vc-PEinGroup">[VC: Proper Group/PE Nesting]</a></td></tr>
|
||
<tr valign="baseline"><td class="diff-chg"><a name="NT-seq"></a>[50]<5D><><EFBFBD></td><td class="diff-chg"><code>seq</code></td><td class="diff-chg"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-chg"><code>'(' <a href="#NT-S">S</a>? <a href="#NT-cp">cp</a> ( <a href="#NT-S">S</a>? ',' <a href="#NT-S">S</a>? <a href="#NT-cp">cp</a> )* <a href="#NT-S">S</a>? ')'</code></td><xsltdebug></xsltdebug><td class="diff-chg"><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E52">[E52]</a> */</i></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#vc-PEinGroup">[VC: Proper Group/PE Nesting]</a></td></tr>
|
||
</tbody></table>
|
||
<p>where each <a href="#NT-Name">Name</a> is the type of an element which
|
||
may appear as a <a title="Parent/Child" href="#dt-parentchild">child</a>. Any content
|
||
particle in a choice list may appear in the <a title="Element content" href="#dt-elemcontent">element
|
||
content</a> at the location where the choice list appears in the grammar;
|
||
content particles occurring in a sequence list must each appear in the <a title="Element content" href="#dt-elemcontent">element content</a> in the order given in the list.
|
||
The optional character following a name or list governs whether the element
|
||
or the content particles in the list may occur one or more (<code>+</code>),
|
||
zero or more (<code>*</code>), or zero or one times (<code>?</code>). The
|
||
absence of such an operator means that the element or content particle must
|
||
appear exactly once. This syntax and meaning are identical to those used in
|
||
the productions in this specification.</p>
|
||
<p>The content of an element matches a content model if and only if it is
|
||
possible to trace out a path through the content model, obeying the sequence,
|
||
choice, and repetition operators and matching each element in the content
|
||
against an element type in the content model. <a title="For Compatibility" href="#dt-compat">For
|
||
compatibility</a>, it is an error if an element in the document can
|
||
match more than one occurrence of an element type in the content model. For
|
||
more information, see <a href="#determinism"><b>E Deterministic Content Models</b></a>.</p>
|
||
|
||
|
||
<div class="constraint"><p class="prefix"><a name="vc-PEinGroup"></a><b>Validity constraint: Proper Group/PE Nesting</b></p><p>Parameter-entity <a title="Replacement Text" href="#dt-repltext">replacement text</a> must be properly nested with <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E11">[E11]</a>parenthesized</span>
|
||
groups. That is to say, if either of the opening or closing parentheses in
|
||
a <a href="#NT-choice">choice</a>, <a href="#NT-seq">seq</a>, or <a href="#NT-Mixed">Mixed</a>
|
||
construct is contained in the replacement text for a <a title="Parameter-entity reference" href="#dt-PERef">parameter
|
||
entity</a>, both must be contained in the same replacement text.</p>
|
||
<div class="diff-chg"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E19">[E19]</a><a title="For interoperability" href="#dt-interop">For interoperability</a>, if a parameter-entity reference
|
||
appears in a <a href="#NT-choice">choice</a>, <a href="#NT-seq">seq</a>, or <a href="#NT-Mixed">Mixed</a> construct, its replacement text should contain at
|
||
least one non-blank character, and neither the first nor last non-blank character
|
||
of the replacement text should be a connector (<code>|</code> or <code>,</code>).</p></div>
|
||
</div>
|
||
<p>Examples of element-content models:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ELEMENT spec (front, body, back?)>
|
||
<!ELEMENT div1 (head, (p | list | note)*, div2*)>
|
||
<!ELEMENT dictionary-body (%div.mix; | %dict.mix;)*></pre></td></tr></table>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="sec-mixed-content"></a>3.2.2 Mixed Content</h4>
|
||
<p>[<a name="dt-mixed" title="Mixed Content">Definition</a>: An element <a title="Start-Tag" href="#dt-stag">type</a>
|
||
has <b>mixed content</b> when elements of that type may contain character
|
||
data, optionally interspersed with <a title="Parent/Child" href="#dt-parentchild">child</a>
|
||
elements.] In this case, the types of the child elements may be constrained,
|
||
but not their order or their number of occurrences:</p>
|
||
|
||
<h5>Mixed-content Declaration</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-Mixed"></a>[51]<5D><><EFBFBD></td><td><code>Mixed</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'(' <a href="#NT-S">S</a>? '#PCDATA' (<a href="#NT-S">S</a>?
|
||
'|' <a href="#NT-S">S</a>? <a href="#NT-Name">Name</a>)* <a href="#NT-S">S</a>?
|
||
')*' </code></td><xsltdebug></xsltdebug></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| '(' <a href="#NT-S">S</a>? '#PCDATA' <a href="#NT-S">S</a>? ')' </code></td><td><a href="#vc-PEinGroup">[VC: Proper Group/PE Nesting]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#vc-MixedChildrenUnique">[VC: No Duplicate Types]</a></td></tr>
|
||
</tbody></table>
|
||
<p>where the <a href="#NT-Name">Name</a>s give the types of elements that
|
||
may appear as children. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E10">[E10]</a>The
|
||
keyword <b>#PCDATA</b> derives historically from the term "parsed
|
||
character data."</span></p>
|
||
<div class="constraint"><p class="prefix"><a name="vc-MixedChildrenUnique"></a><b>Validity constraint: No Duplicate Types</b></p><p>The
|
||
same name must not appear more than once in a single mixed-content declaration.</p>
|
||
</div>
|
||
<p>Examples of mixed content declarations:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ELEMENT p (#PCDATA|a|ul|b|i|em)*>
|
||
<!ELEMENT p (#PCDATA | %font; | %phrase; | %special; | %form;)* >
|
||
<!ELEMENT b (#PCDATA)></pre></td></tr></table>
|
||
</div>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="attdecls"></a>3.3 Attribute-List Declarations</h3>
|
||
<p><a title="Attribute" href="#dt-attr">Attributes</a> are used to associate name-value
|
||
pairs with <a title="Element" href="#dt-element">elements</a>. Attribute specifications
|
||
may appear only within <a title="Start-Tag" href="#dt-stag">start-tags</a> and <a title="empty-element tag" href="#dt-eetag">empty-element tags</a>; thus, the productions used to
|
||
recognize them appear in <a href="#sec-starttags"><b>3.1 Start-Tags, End-Tags, and Empty-Element Tags</b></a>. Attribute-list declarations
|
||
may be used:</p>
|
||
<ul>
|
||
<li><p>To define the set of attributes pertaining to a given element type.</p>
|
||
</li>
|
||
<li><p>To establish type constraints for these attributes.</p></li>
|
||
<li><p>To provide <a title="Attribute Default" href="#dt-default">default values</a> for
|
||
attributes.</p></li>
|
||
</ul>
|
||
<p>[<a name="dt-attdecl" title="Attribute-List Declaration">Definition</a>: <b>Attribute-list
|
||
declarations</b> specify the name, data type, and default value (if any)
|
||
of each attribute associated with a given element type:]</p>
|
||
|
||
<h5>Attribute-list Declaration</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-AttlistDecl"></a>[52]<5D><><EFBFBD></td><td><code>AttlistDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<!ATTLIST' <a href="#NT-S">S</a> <a href="#NT-Name">Name</a> <a href="#NT-AttDef">AttDef</a>* <a href="#NT-S">S</a>? '>'</code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-AttDef"></a>[53]<5D><><EFBFBD></td><td><code>AttDef</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-S">S</a> <a href="#NT-Name">Name</a> <a href="#NT-S">S</a> <a href="#NT-AttType">AttType</a> <a href="#NT-S">S</a> <a href="#NT-DefaultDecl">DefaultDecl</a></code></td><xsltdebug></xsltdebug></tr></tbody></table>
|
||
<p>The <a href="#NT-Name">Name</a> in the <a href="#NT-AttlistDecl">AttlistDecl</a>
|
||
rule is the type of an element. At user option, an XML processor may issue
|
||
a warning if attributes are declared for an element type not itself declared,
|
||
but this is not an error. The <a href="#NT-Name">Name</a> in the <a href="#NT-AttDef">AttDef</a>
|
||
rule is the name of the attribute.</p>
|
||
<p>When more than one <a href="#NT-AttlistDecl">AttlistDecl</a> is provided
|
||
for a given element type, the contents of all those provided are merged. When
|
||
more than one definition is provided for the same attribute of a given element
|
||
type, the first declaration is binding and later declarations are ignored. <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E9">[E9]</a><a title="For interoperability" href="#dt-interop">For interoperability,</a> writers of DTDs may choose
|
||
to provide at most one attribute-list declaration for a given element type,
|
||
at most one attribute definition for a given attribute name in an attribute-list
|
||
declaration, and at least one attribute definition in each attribute-list
|
||
declaration.</span> For interoperability, an XML processor may at user option
|
||
issue a warning when more than one attribute-list declaration is provided
|
||
for a given element type, or more than one attribute definition is provided
|
||
for a given attribute, but this is not an error.</p>
|
||
<div class="div3">
|
||
|
||
<h4><a name="sec-attribute-types"></a>3.3.1 Attribute Types</h4>
|
||
<p>XML attribute types are of three kinds: a string type, a set of tokenized
|
||
types, and enumerated types. The string type may take any literal string as
|
||
a value; the tokenized types have varying lexical and semantic constraints<span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E8">[E8]</a>.
|
||
The validity constraints noted in the grammar are applied after the attribute
|
||
value has been normalized as described in <a href="#attdecls"><b>3.3 Attribute-List Declarations</b></a>.</span></p>
|
||
|
||
<h5>Attribute Types</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-AttType"></a>[54]<5D><><EFBFBD></td><td><code>AttType</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-StringType">StringType</a> | <a href="#NT-TokenizedType">TokenizedType</a>
|
||
| <a href="#NT-EnumeratedType">EnumeratedType</a> </code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-StringType"></a>[55]<5D><><EFBFBD></td><td><code>StringType</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'CDATA'</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-TokenizedType"></a>[56]<5D><><EFBFBD></td><td><code>TokenizedType</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'ID'</code></td><xsltdebug></xsltdebug><td><a href="#id">[VC: ID]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#one-id-per-el">[VC: One ID per Element Type]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#id-default">[VC: ID Attribute Default]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| 'IDREF'</code></td><td><a href="#idref">[VC: IDREF]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| 'IDREFS'</code></td><td><a href="#idref">[VC: IDREF]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| 'ENTITY'</code></td><td><a href="#entname">[VC: Entity Name]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| 'ENTITIES'</code></td><td><a href="#entname">[VC: Entity Name]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| 'NMTOKEN'</code></td><td><a href="#nmtok">[VC: Name Token]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| 'NMTOKENS'</code></td><td><a href="#nmtok">[VC: Name Token]</a></td></tr>
|
||
</tbody></table>
|
||
<div class="constraint"><p class="prefix"><a name="id"></a><b>Validity constraint: ID</b></p><p>Values of type <b>ID</b> must match the <a href="#NT-Name">Name</a> production. A name must not appear more than once
|
||
in an XML document as a value of this type; i.e., ID values must uniquely
|
||
identify the elements which bear them.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="one-id-per-el"></a><b>Validity constraint: One ID per Element Type</b></p><p>No element
|
||
type may have more than one ID attribute specified.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="id-default"></a><b>Validity constraint: ID Attribute Default</b></p><p>An ID attribute
|
||
must have a declared default of <b>#IMPLIED</b> or <b>#REQUIRED</b>.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="idref"></a><b>Validity constraint: IDREF</b></p><p>Values of type <b>IDREF</b> must
|
||
match the <a href="#NT-Name">Name</a> production, and values of type <b>IDREFS</b>
|
||
must match <a href="#NT-Names">Names</a>; each <a href="#NT-Name">Name</a>
|
||
must match the value of an ID attribute on some element in the XML document;
|
||
i.e. <b>IDREF</b> values must match the value of some ID attribute.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="entname"></a><b>Validity constraint: Entity Name</b></p><p>Values of type <b>ENTITY</b>
|
||
must match the <a href="#NT-Name">Name</a> production, values of type <b>ENTITIES</b>
|
||
must match <a href="#NT-Names">Names</a>; each <a href="#NT-Name">Name</a>
|
||
must match the name of an <a title="Unparsed Entity" href="#dt-unparsed">unparsed entity</a>
|
||
declared in the <a title="Document Type Declaration" href="#dt-doctype">DTD</a>.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="nmtok"></a><b>Validity constraint: Name Token</b></p><p>Values of type <b>NMTOKEN</b>
|
||
must match the <a href="#NT-Nmtoken">Nmtoken</a> production; values of type <b>NMTOKENS</b>
|
||
must match <a title="" href="#NT-Nmtokens">Nmtokens</a>.</p>
|
||
</div>
|
||
|
||
<p>[<a name="dt-enumerated" title="Enumerated Attribute Values">Definition</a>: <b>Enumerated attributes</b> can take one of a list of values
|
||
provided in the declaration]. There are two kinds of enumerated types:</p>
|
||
|
||
<h5>Enumerated Attribute Types</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-EnumeratedType"></a>[57]<5D><><EFBFBD></td><td><code>EnumeratedType</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-NotationType">NotationType</a>
|
||
| <a href="#NT-Enumeration">Enumeration</a> </code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-NotationType"></a>[58]<5D><><EFBFBD></td><td><code>NotationType</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'NOTATION' <a href="#NT-S">S</a> '(' <a href="#NT-S">S</a>? <a href="#NT-Name">Name</a> (<a href="#NT-S">S</a>? '|' <a href="#NT-S">S</a>? <a href="#NT-Name">Name</a>)* <a href="#NT-S">S</a>? ')' </code></td><xsltdebug></xsltdebug><td><a href="#notatn">[VC: Notation Attributes]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td class="diff-add"><a href="#OneNotationPer">[VC: One
|
||
Notation Per Element Type]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td class="diff-add"><a href="#NoNotationEmpty">[VC: No
|
||
Notation on Empty Element]</a></td></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-Enumeration"></a>[59]<5D><><EFBFBD></td><td><code>Enumeration</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'(' <a href="#NT-S">S</a>? <a href="#NT-Nmtoken">Nmtoken</a>
|
||
(<a href="#NT-S">S</a>? '|' <a href="#NT-S">S</a>? <a href="#NT-Nmtoken">Nmtoken</a>)* <a href="#NT-S">S</a>? ')'</code></td><xsltdebug></xsltdebug><td><a href="#enum">[VC: Enumeration]</a></td></tr></tbody></table>
|
||
<p>A <b>NOTATION</b> attribute identifies a <a title="Notation" href="#dt-notation">notation</a>,
|
||
declared in the DTD with associated system and/or public identifiers, to be
|
||
used in interpreting the element to which the attribute is attached.</p>
|
||
<div class="constraint"><p class="prefix"><a name="notatn"></a><b>Validity constraint: Notation Attributes</b></p><p>Values of this type
|
||
must match one of the <a href="#Notations"><cite>notation</cite></a> names
|
||
included in the declaration; all notation names in the declaration must be
|
||
declared.</p>
|
||
</div>
|
||
<div class="diff-add"><div class="constraint"><p class="prefix"><a name="OneNotationPer"></a><b>Validity constraint: <a href="http://www.w3.org/XML/xml-19980210-errata#E7">[E7]</a>One
|
||
Notation Per Element Type</b></p><p>No element type may have more than one <b>NOTATION</b>
|
||
attribute specified.</p>
|
||
</div></div>
|
||
<div class="diff-add"><div class="constraint"><p class="prefix"><a name="NoNotationEmpty"></a><b>Validity constraint: <a href="http://www.w3.org/XML/xml-19980210-errata#E68">[E68]</a>No
|
||
Notation on Empty Element</b></p><p><a title="For Compatibility" href="#dt-compat">For compatibility</a>,
|
||
an attribute of type <b>NOTATION</b> must not be declared on an element
|
||
declared <b>EMPTY</b>.</p>
|
||
</div></div>
|
||
<div class="constraint"><p class="prefix"><a name="enum"></a><b>Validity constraint: Enumeration</b></p><p>Values of this type must match
|
||
one of the <a href="#NT-Nmtoken">Nmtoken</a> tokens in the declaration.</p>
|
||
</div>
|
||
<p><a title="For interoperability" href="#dt-interop">For interoperability,</a> the same <a href="#NT-Nmtoken">Nmtoken</a> should not occur more than once in the enumerated
|
||
attribute types of a single element type.</p>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="sec-attr-defaults"></a>3.3.2 Attribute Defaults</h4>
|
||
<p>An <a title="Attribute-List Declaration" href="#dt-attdecl">attribute declaration</a> provides information
|
||
on whether the attribute's presence is required, and if not, how an XML processor
|
||
should react if a declared attribute is absent in a document.</p>
|
||
|
||
<h5>Attribute Defaults</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-DefaultDecl"></a>[60]<5D><><EFBFBD></td><td><code>DefaultDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'#REQUIRED' |<7C>'#IMPLIED' </code></td><xsltdebug></xsltdebug></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| (('#FIXED' S)? <a href="#NT-AttValue">AttValue</a>)</code></td><td><a href="#RequiredAttr">[VC: Required Attribute]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#defattrvalid">[VC: Attribute Default Legal]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#CleanAttrVals">[WFC: No < in Attribute Values]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#FixedAttr">[VC: Fixed Attribute Default]</a></td></tr>
|
||
</tbody></table>
|
||
<p>In an attribute declaration, <b>#REQUIRED</b> means that the attribute
|
||
must always be provided, <b>#IMPLIED</b> that no default value is provided. [<a name="dt-default" title="Attribute Default">Definition</a>: If
|
||
the declaration is neither <b>#REQUIRED</b> nor <b>#IMPLIED</b>, then
|
||
the <a href="#NT-AttValue">AttValue</a> value contains the declared <b>default</b>
|
||
value; the <b>#FIXED</b> keyword states that the attribute must always have
|
||
the default value. If a default value is declared, when an XML processor encounters
|
||
an omitted attribute, it is to behave as though the attribute were present
|
||
with the declared default value.]</p>
|
||
<div class="constraint"><p class="prefix"><a name="RequiredAttr"></a><b>Validity constraint: Required Attribute</b></p><p>If the default
|
||
declaration is the keyword <b>#REQUIRED</b>, then the attribute must be
|
||
specified for all elements of the type in the attribute-list declaration.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="defattrvalid"></a><b>Validity constraint: Attribute Default Legal</b></p><p>The declared
|
||
default value must meet the lexical constraints of the declared attribute
|
||
type.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="FixedAttr"></a><b>Validity constraint: Fixed Attribute Default</b></p><p>If an attribute
|
||
has a default value declared with the <b>#FIXED</b> keyword, instances of
|
||
that attribute must match the default value.</p>
|
||
</div>
|
||
<p>Examples of attribute-list declarations:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ATTLIST termdef
|
||
id ID #REQUIRED
|
||
name CDATA #IMPLIED>
|
||
<!ATTLIST list
|
||
type (bullets|ordered|glossary) "ordered">
|
||
<!ATTLIST form
|
||
method CDATA #FIXED "POST"></pre></td></tr></table>
|
||
</div>
|
||
<div class="diff-chg"><div class="div3">
|
||
|
||
<h4><a name="AVNormalize"></a>3.3.3 <a href="http://www.w3.org/XML/xml-19980210-errata#E70">[E70]</a>Attribute-Value
|
||
Normalization</h4>
|
||
<p>Before the value of an attribute is passed to the application or checked
|
||
for validity, the XML processor must normalize the attribute value by applying
|
||
the algorithm below, or by using some other method such that the value passed
|
||
to the application is the same as that produced by the algorithm.</p>
|
||
<ol>
|
||
<li><p>All line breaks must have been normalized on input to #xA as described
|
||
in <a href="#sec-line-ends"><b>2.11 End-of-Line Handling</b></a>, so the rest of this algorithm operates
|
||
on text normalized in this way.</p></li>
|
||
<li><p>Begin with a normalized value consisting of the empty string.</p>
|
||
</li>
|
||
<li><p>For each character, entity reference, or character reference in the
|
||
unnormalized attribute value, beginning with the first and continuing to the
|
||
last, do the following:</p>
|
||
<ul>
|
||
<li><p>For a character reference, append the referenced character to the
|
||
normalized value.</p></li>
|
||
<li><p>For an entity reference, recursively apply step 3 of this algorithm
|
||
to the replacement text of the entity.</p></li>
|
||
<li><p>For a white space character (#x20, #xD, #xA, #x9), append a space
|
||
character (#x20) to the normalized value.</p></li>
|
||
<li><p>For another character, append the character to the normalized value.</p>
|
||
</li>
|
||
</ul>
|
||
</li>
|
||
</ol>
|
||
<p>If the attribute type is not CDATA, then the XML processor must further
|
||
process the normalized attribute value by discarding any leading and trailing
|
||
space (#x20) characters, and by replacing sequences of space (#x20) characters
|
||
by a single space (#x20) character.</p>
|
||
<p>Note that if the unnormalized attribute value contains a character reference
|
||
to a white space character other than space (#x20), the normalized value contains
|
||
the referenced character itself (#xD, #xA or #x9). This contrasts with the
|
||
case where the unnormalized value contains a white space character (not a
|
||
reference), which is replaced with a space character (#x20) in the normalized
|
||
value and also contrasts with the case where the unnormalized value contains
|
||
an entity reference whose replacement text contains a white space character;
|
||
being recursively processed, the white space character is replaced with a
|
||
space character (#x20) in the normalized value.</p>
|
||
<p>All attributes for which no declaration has been read should be treated
|
||
by a non-validating <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E95">[E95]</a>processor</span>
|
||
as if declared <b>CDATA</b>.</p>
|
||
<p>Following are examples of attribute normalization. Given the following
|
||
declarations:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ENTITY d "&#xD;">
|
||
<!ENTITY a "&#xA;">
|
||
<!ENTITY da "&#xD;&#xA;"></pre></td></tr></table>
|
||
<p>the attribute specifications in the left column below would be normalized
|
||
to the character sequences of the middle column if the attribute <code>a</code>
|
||
is declared <b>NMTOKENS</b> and to those of the right columns if <code>a</code>
|
||
is declared <b>CDATA</b>.</p>
|
||
<table border="1" frame="border"><thead><tr><th rowspan="1" colspan="1">Attribute specification</th>
|
||
<th rowspan="1" colspan="1">a is NMTOKENS</th><th rowspan="1" colspan="1">a is CDATA</th></tr></thead><tbody><tr><td rowspan="1" colspan="1"><table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre>a="
|
||
|
||
xyz"</pre></td></tr></table></td><td rowspan="1" colspan="1"><code>x y z</code></td><td rowspan="1" colspan="1"><code>#x20 #x20 x y z</code></td>
|
||
</tr><tr><td rowspan="1" colspan="1"><table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre>a="&d;&d;A&a;&a;B&da;"</pre></td></tr></table></td><td rowspan="1" colspan="1"><code>A
|
||
#x20 B</code></td><td rowspan="1" colspan="1"><code>#x20 #x20 A #x20 #x20 B #x20 #x20</code></td>
|
||
</tr><tr><td rowspan="1" colspan="1"><table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre>a=
|
||
"&#xd;&#xd;A&#xa;&#xa;B&#xd;&#xa;"</pre></td></tr></table></td><td rowspan="1" colspan="1"><code>#xD
|
||
#xD A #xA #xA B #xD #xA</code></td><td rowspan="1" colspan="1"><code>#xD #xD A #xA #xA B #xD #xD</code></td>
|
||
</tr></tbody></table>
|
||
<p>Note that the last example is invalid (but well-formed) if <code>a</code>
|
||
is declared to be of type <b>NMTOKENS</b>.</p>
|
||
</div></div>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-condition-sect"></a>3.4 Conditional Sections</h3>
|
||
<p>[<a name="dt-cond-section" title="conditional section">Definition</a>: <b>Conditional
|
||
sections</b> are portions of the <a title="Document Type Declaration" href="#dt-doctype">document type
|
||
declaration external subset</a> which are included in, or excluded from,
|
||
the logical structure of the DTD based on the keyword which governs them.]</p>
|
||
|
||
<h5>Conditional Section</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-conditionalSect"></a>[61]<5D><><EFBFBD></td><td><code>conditionalSect</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-includeSect">includeSect</a> | <a href="#NT-ignoreSect">ignoreSect</a> </code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-includeSect"></a>[62]<5D><><EFBFBD></td><td><code>includeSect</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<![' S? 'INCLUDE' S? '[' <a href="#NT-extSubsetDecl">extSubsetDecl</a>
|
||
']]>' </code></td><xsltdebug></xsltdebug><td><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</a> */</i></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td class="diff-add"><a href="#condsec-nesting">[VC: Proper
|
||
Conditional Section/PE Nesting]</a></td></tr>
|
||
<tr valign="baseline"><td><a name="NT-ignoreSect"></a>[63]<5D><><EFBFBD></td><td><code>ignoreSect</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<![' S? 'IGNORE' S? '[' <a href="#NT-ignoreSectContents">ignoreSectContents</a>*
|
||
']]>'</code></td><xsltdebug></xsltdebug><td><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</a> */</i></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td class="diff-add"><a href="#condsec-nesting">[VC: Proper
|
||
Conditional Section/PE Nesting]</a></td></tr>
|
||
<tr valign="baseline"><td><a name="NT-ignoreSectContents"></a>[64]<5D><><EFBFBD></td><td><code>ignoreSectContents</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-Ignore">Ignore</a> ('<![' <a href="#NT-ignoreSectContents">ignoreSectContents</a> ']]>' <a href="#NT-Ignore">Ignore</a>)*</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-Ignore"></a>[65]<5D><><EFBFBD></td><td><code>Ignore</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-Char">Char</a>* - (<a href="#NT-Char">Char</a>*
|
||
('<![' | ']]>') <a href="#NT-Char">Char</a>*) </code></td><xsltdebug></xsltdebug></tr>
|
||
</tbody></table>
|
||
<div class="diff-add"><div class="constraint"><p class="prefix"><a name="condsec-nesting"></a><b>Validity constraint: <a href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</a>Proper
|
||
Conditional Section/PE Nesting</b></p><p>If any of the "<code><![</code>",
|
||
"<code>[</code>", or "<code>]]></code>" of a conditional section is contained
|
||
in the replacement text for a parameter-entity reference, all of them must
|
||
be contained in the same replacement text.</p>
|
||
</div></div>
|
||
<p>Like the internal and external DTD subsets, a conditional section may contain
|
||
one or more complete declarations, comments, processing instructions, or nested
|
||
conditional sections, intermingled with white space.</p>
|
||
<p>If the keyword of the conditional section is <b>INCLUDE</b>, then the
|
||
contents of the conditional section are part of the DTD. If the keyword of
|
||
the conditional section is <b>IGNORE</b>, then the contents of the conditional
|
||
section are not logically part of the DTD. <span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</a>Note that
|
||
for reliable parsing, the contents of even ignored conditional sections must
|
||
be read in order to detect nested conditional sections and ensure that the
|
||
end of the outermost (ignored) conditional section is properly detected.</span>
|
||
If a conditional section with a keyword of <b>INCLUDE</b> occurs within
|
||
a larger conditional section with a keyword of <b>IGNORE</b>, both the outer
|
||
and the inner conditional sections are ignored.<span class="diff-add"> <a href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</a>The contents
|
||
of an ignored conditional section are parsed by ignoring all characters after
|
||
the "<code>[</code>" following the keyword, except conditional section starts
|
||
"<code><![</code>" and ends "<code>]]></code>", until the matching conditional
|
||
section end is found. Parameter entity references are not recognized in this
|
||
process.</span></p>
|
||
<p>If the keyword of the conditional section is a parameter-entity reference,
|
||
the parameter entity must be replaced by its content before the processor
|
||
decides whether to include or ignore the conditional section.</p>
|
||
<p>An example:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ENTITY % draft 'INCLUDE' >
|
||
<!ENTITY % final 'IGNORE' >
|
||
|
||
<![%draft;[
|
||
<!ELEMENT book (comments*, title, body, supplements?)>
|
||
]]>
|
||
<![%final;[
|
||
<!ELEMENT book (title, body, supplements?)>
|
||
]]></pre></td></tr></table>
|
||
</div>
|
||
|
||
</div>
|
||
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-physical-struct"></a>4 Physical Structures</h2>
|
||
<p>[<a name="dt-entity" title="Entity">Definition</a>: An XML document may consist of one
|
||
or many storage units. <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E6">[E6]</a>These
|
||
are called <b>entities</b>; they all have <b>content</b> and are
|
||
all (except for the <a title="Document Entity" href="#dt-docent">document entity</a> and
|
||
the <a title="Document Type Declaration" href="#dt-doctype">external DTD subset</a>) identified by
|
||
entity <b>name</b></span>.] Each XML document has one entity
|
||
called the <a title="Document Entity" href="#dt-docent">document entity</a>, which serves
|
||
as the starting point for the <a title="XML Processor" href="#dt-xml-proc">XML processor</a>
|
||
and may contain the whole document.</p>
|
||
<p>Entities may be either parsed or unparsed. [<a name="dt-parsedent" title="Text Entity">Definition</a>: A <b>parsed
|
||
entity's</b> contents are referred to as its <a title="Replacement Text" href="#dt-repltext">replacement
|
||
text</a>; this <a title="Text" href="#dt-text">text</a> is considered an
|
||
integral part of the document.]</p>
|
||
<p>[<a name="dt-unparsed" title="Unparsed Entity">Definition</a>: An <b>unparsed entity</b>
|
||
is a resource whose contents may or may not be <a title="Text" href="#dt-text">text</a>,
|
||
and if text, <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E25">[E25]</a>may
|
||
be other than</span> XML. Each unparsed entity has an associated <a title="Notation" href="#dt-notation">notation</a>, identified by name. Beyond a requirement
|
||
that an XML processor make the identifiers for the entity and notation available
|
||
to the application, XML places no constraints on the contents of unparsed
|
||
entities.]</p>
|
||
<p>Parsed entities are invoked by name using entity references; unparsed entities
|
||
by name, given in the value of <b>ENTITY</b> or <b>ENTITIES</b> attributes.</p>
|
||
<p>[<a name="gen-entity" title="general entity">Definition</a>: <b>General entities</b>
|
||
are entities for use within the document content. In this specification, general
|
||
entities are sometimes referred to with the unqualified term <em>entity</em>
|
||
when this leads to no ambiguity.] [<a name="dt-PE" title="Parameter entity">Definition</a>: <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E53">[E53]</a><b>Parameter
|
||
entities</b></span> are parsed entities for use within the DTD.]
|
||
These two types of entities use different forms of reference and are recognized
|
||
in different contexts. Furthermore, they occupy different namespaces; a parameter
|
||
entity and a general entity with the same name are two distinct entities.</p>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-references"></a>4.1 Character and Entity References</h3>
|
||
<p>[<a name="dt-charref" title="Character Reference">Definition</a>: A <b>character
|
||
reference</b> refers to a specific character in the ISO/IEC 10646 character
|
||
set, for example one not directly accessible from available input devices.]</p>
|
||
|
||
<h5>Character Reference</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-CharRef"></a>[66]<5D><><EFBFBD></td><td><code>CharRef</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'&#' [0-9]+ ';' </code></td><xsltdebug></xsltdebug></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| '&#x' [0-9a-fA-F]+ ';'</code></td><td><a href="#wf-Legalchar">[WFC: Legal Character]</a></td></tr></tbody></table>
|
||
<div class="constraint"><p class="prefix"><a name="wf-Legalchar"></a><b>Well-formedness constraint: Legal Character</b></p><p>Characters referred
|
||
to using character references must match the production for <a title="" href="#NT-Char">Char</a>.</p>
|
||
</div>
|
||
<p>If the character reference begins with "<code>&#x</code>",
|
||
the digits and letters up to the terminating <code>;</code> provide a hexadecimal
|
||
representation of the character's code point in ISO/IEC 10646. If it begins
|
||
just with "<code>&#</code>", the digits up to the terminating <code>;</code>
|
||
provide a decimal representation of the character's code point.</p>
|
||
<p>[<a name="dt-entref" title="Entity Reference">Definition</a>: An <b>entity reference</b>
|
||
refers to the content of a named entity.] [<a name="dt-GERef" title="General Entity Reference">Definition</a>: References to parsed general entities use
|
||
ampersand (<code>&</code>) and semicolon (<code>;</code>) as delimiters.] [<a name="dt-PERef" title="Parameter-entity reference">Definition</a>: <b>Parameter-entity references</b>
|
||
use percent-sign (<code>%</code>) and semicolon (<code>;</code>) as delimiters.]</p>
|
||
|
||
<h5>Entity Reference</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-Reference"></a>[67]<5D><><EFBFBD></td><td><code>Reference</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-EntityRef">EntityRef</a> | <a href="#NT-CharRef">CharRef</a></code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-EntityRef"></a>[68]<5D><><EFBFBD></td><td><code>EntityRef</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'&' <a href="#NT-Name">Name</a> ';'</code></td><xsltdebug></xsltdebug><td><a href="#wf-entdeclared">[WFC: Entity Declared]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#vc-entdeclared">[VC: Entity Declared]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#textent">[WFC: Parsed Entity]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#norecursion">[WFC: No Recursion]</a></td></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-PEReference"></a>[69]<5D><><EFBFBD></td><td><code>PEReference</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'%' <a href="#NT-Name">Name</a> ';'</code></td><xsltdebug></xsltdebug><td><a href="#vc-entdeclared">[VC: Entity Declared]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#norecursion">[WFC: No Recursion]</a></td></tr><tr valign="baseline"><td></td><td></td><td></td><td></td><td><a href="#indtd">[WFC: In DTD]</a></td></tr></tbody></table>
|
||
<div class="constraint"><p class="prefix"><a name="wf-entdeclared"></a><b>Well-formedness constraint: Entity Declared</b></p><p>In a document
|
||
without any DTD, a document with only an internal DTD subset which contains
|
||
no parameter entity references, or a document with "<code>standalone='yes'</code>", <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E34">[E34]</a>for
|
||
an entity reference that does not occur within the external subset or a parameter
|
||
entity, the <a href="#NT-Name">Name</a> given in the entity reference must <a title="match" href="#dt-match">match</a> that in an <a href="#sec-entity-decl"><cite>entity
|
||
declaration</cite></a> that does not occur within the external subset or a
|
||
parameter entity</span>, except that well-formed documents need not declare
|
||
any of the following entities: <code>amp</code>,
|
||
<code>lt</code>,
|
||
<code>gt</code>,
|
||
<code>apos</code>,
|
||
<code>quot</code>. <span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E29">[E29]</a>The declaration
|
||
of a parameter entity must precede any reference to it. Similarly, </span>The
|
||
declaration of a general entity must precede any reference to it which appears
|
||
in a default value in an attribute-list declaration.</p>
|
||
<p>Note that if entities are declared in the external subset or in external
|
||
parameter entities, a non-validating processor is <a href="#include-if-valid"><cite>not
|
||
obligated to</cite></a> read and process their declarations; for such documents,
|
||
the rule that an entity must be declared is a well-formedness constraint only
|
||
if <a href="#sec-rmd"><cite>standalone='yes'</cite></a>.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="vc-entdeclared"></a><b>Validity constraint: Entity Declared</b></p><p>In a document with
|
||
an external subset or external parameter entities with "<code>standalone='no'</code>",
|
||
the <a href="#NT-Name">Name</a> given in the entity reference must <a title="match" href="#dt-match">match</a> that in an <a href="#sec-entity-decl"><cite>entity
|
||
declaration</cite></a>. For interoperability, valid documents should declare
|
||
the entities <code>amp</code>,
|
||
<code>lt</code>,
|
||
<code>gt</code>,
|
||
<code>apos</code>,
|
||
<code>quot</code>, in the form specified in <a href="#sec-predefined-ent"><b>4.6 Predefined Entities</b></a>.
|
||
The declaration of a parameter entity must precede any reference to it. Similarly,
|
||
the declaration of a general entity must precede any <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E92">[E92]</a>attribute-list
|
||
declaration containing a default value with a direct or indirect reference
|
||
to that general entity.</span></p>
|
||
</div>
|
||
|
||
<div class="constraint"><p class="prefix"><a name="textent"></a><b>Well-formedness constraint: Parsed Entity</b></p><p>An entity reference must
|
||
not contain the name of an <a title="Unparsed Entity" href="#dt-unparsed">unparsed entity</a>.
|
||
Unparsed entities may be referred to only in <a title="Attribute Value" href="#dt-attrval">attribute
|
||
values</a> declared to be of type <b>ENTITY</b> or <b>ENTITIES</b>.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="norecursion"></a><b>Well-formedness constraint: No Recursion</b></p><p>A parsed entity must
|
||
not contain a recursive reference to itself, either directly or indirectly.</p>
|
||
</div>
|
||
<div class="constraint"><p class="prefix"><a name="indtd"></a><b>Well-formedness constraint: In DTD</b></p><p>Parameter-entity references may
|
||
only appear in the <a title="Document Type Declaration" href="#dt-doctype">DTD</a>.</p>
|
||
</div>
|
||
<p>Examples of character and entity references:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre>Type <key>less-than</key> (&#x3C;) to save options.
|
||
This document was prepared on &docdate; and
|
||
is classified &security-level;.</pre></td></tr></table>
|
||
<p>Example of a parameter-entity reference:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!-- declare the parameter entity "ISOLat2"... -->
|
||
<!ENTITY % ISOLat2
|
||
SYSTEM "http://www.xml.com/iso/isolat2-xml.entities" >
|
||
<!-- ... now reference it. -->
|
||
%ISOLat2;</pre></td></tr></table>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-entity-decl"></a>4.2 Entity Declarations</h3>
|
||
<p>[<a name="dt-entdecl" title="entity declaration">Definition</a>: Entities are declared
|
||
thus:]</p>
|
||
|
||
<h5>Entity Declaration</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-EntityDecl"></a>[70]<5D><><EFBFBD></td><td><code>EntityDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-GEDecl">GEDecl</a> | <a href="#NT-PEDecl">PEDecl</a></code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-GEDecl"></a>[71]<5D><><EFBFBD></td><td><code>GEDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<!ENTITY' <a href="#NT-S">S</a> <a href="#NT-Name">Name</a> <a href="#NT-S">S</a> <a href="#NT-EntityDef">EntityDef</a> <a href="#NT-S">S</a>?
|
||
'>'</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-PEDecl"></a>[72]<5D><><EFBFBD></td><td><code>PEDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<!ENTITY' <a href="#NT-S">S</a> '%' <a href="#NT-S">S</a> <a href="#NT-Name">Name</a> <a href="#NT-S">S</a> <a href="#NT-PEDef">PEDef</a> <a href="#NT-S">S</a>? '>'</code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-EntityDef"></a>[73]<5D><><EFBFBD></td><td><code>EntityDef</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-EntityValue">EntityValue</a> | (<a href="#NT-ExternalID">ExternalID</a> <a href="#NT-NDataDecl">NDataDecl</a>?)</code></td><xsltdebug></xsltdebug></tr>
|
||
|
||
<tr valign="baseline"><td><a name="NT-PEDef"></a>[74]<5D><><EFBFBD></td><td><code>PEDef</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-EntityValue">EntityValue</a> | <a href="#NT-ExternalID">ExternalID</a></code></td><xsltdebug></xsltdebug></tr>
|
||
</tbody></table>
|
||
<p>The <a href="#NT-Name">Name</a> identifies the entity in an <a title="Entity Reference" href="#dt-entref">entity
|
||
reference</a> or, in the case of an unparsed entity, in the value of
|
||
an <b>ENTITY</b> or <b>ENTITIES</b> attribute. If the same entity is declared
|
||
more than once, the first declaration encountered is binding; at user option,
|
||
an XML processor may issue a warning if entities are declared multiple times.</p>
|
||
<div class="div3">
|
||
|
||
<h4><a name="sec-internal-ent"></a>4.2.1 Internal Entities</h4>
|
||
<p>[<a name="dt-internent" title="Internal Entity Replacement Text">Definition</a>: If the
|
||
entity definition is an <a href="#NT-EntityValue">EntityValue</a>, the defined
|
||
entity is called an <b>internal entity</b>. There is no separate physical
|
||
storage object, and the content of the entity is given in the declaration.]
|
||
Note that some processing of entity and character references in the <a title="Literal Entity Value" href="#dt-litentval">literal entity value</a> may be required to produce
|
||
the correct <a title="Replacement Text" href="#dt-repltext">replacement text</a>: see <a href="#intern-replacement"><b>4.5 Construction of Internal Entity Replacement Text</b></a>.</p>
|
||
<p>An internal entity is a <a title="Text Entity" href="#dt-parsedent">parsed entity</a>.</p>
|
||
<p>Example of an internal entity declaration:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ENTITY Pub-Status "This is a pre-release of the
|
||
specification."></pre></td></tr></table>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="sec-external-ent"></a>4.2.2 External Entities</h4>
|
||
<p>[<a name="dt-extent" title="External Entity">Definition</a>: If the entity is not internal,
|
||
it is an <b>external entity</b>, declared as follows:]</p>
|
||
|
||
<h5>External Entity Declaration</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-ExternalID"></a>[75]<5D><><EFBFBD></td><td><code>ExternalID</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'SYSTEM' <a href="#NT-S">S</a> <a href="#NT-SystemLiteral">SystemLiteral</a></code></td><xsltdebug></xsltdebug></tr><tr valign="baseline"><td></td><td></td><td></td><td><code>| 'PUBLIC' <a href="#NT-S">S</a> <a href="#NT-PubidLiteral">PubidLiteral</a> <a href="#NT-S">S</a> <a href="#NT-SystemLiteral">SystemLiteral</a> </code></td></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-NDataDecl"></a>[76]<5D><><EFBFBD></td><td><code>NDataDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-S">S</a> 'NDATA' <a href="#NT-S">S</a> <a href="#NT-Name">Name</a></code></td><xsltdebug></xsltdebug><td><a href="#not-declared">[VC: Notation Declared]</a></td></tr></tbody></table>
|
||
<p>If the <a href="#NT-NDataDecl">NDataDecl</a> is present, this is a general <a title="Unparsed Entity" href="#dt-unparsed">unparsed entity</a>; otherwise it is a parsed entity.</p>
|
||
<div class="constraint"><p class="prefix"><a name="not-declared"></a><b>Validity constraint: Notation Declared</b></p><p>The <a href="#NT-Name">Name</a>
|
||
must match the declared name of a <a title="Notation" href="#dt-notation">notation</a>.</p>
|
||
</div>
|
||
<p><span class="diff-chg">[<a name="dt-sysid" title="System Identifier">Definition</a>: The <a href="#NT-SystemLiteral">SystemLiteral</a> is called the entity's <b>system
|
||
identifier</b>. It is a <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E88">[E88]</a>URI
|
||
reference</span><span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E66">[E66]</a>
|
||
(as defined in <a href="#rfc2396">[IETF RFC 2396]</a>, updated by <a href="#rfc2732">[IETF RFC 2732]</a>)</span>, <a href="http://www.w3.org/XML/xml-19980210-errata#E76">[E76]</a>meant
|
||
to be dereferenced to obtain input for the XML processor to construct the
|
||
entity's replacement text.] It is an error for a fragment identifier
|
||
(beginning with a <code>#</code> character) to be part of a system identifier.</span>
|
||
Unless otherwise provided by information outside the scope of this specification
|
||
(e.g. a special XML element type defined by a particular DTD, or a processing
|
||
instruction defined by a particular application specification), relative URIs
|
||
are relative to the location of the resource within which the entity declaration
|
||
occurs. A URI might thus be relative to the <a title="Document Entity" href="#dt-docent">document
|
||
entity</a>, to the entity containing the <a title="Document Type Declaration" href="#dt-doctype">external
|
||
DTD subset</a>, or to some other <a title="External Entity" href="#dt-extent">external parameter
|
||
entity</a>.</p>
|
||
<div class="diff-chg"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E78">[E78]</a>URI
|
||
references require encoding and escaping of certain characters. The disallowed
|
||
characters include all non-ASCII characters, plus the excluded characters
|
||
listed in Section 2.4 of <a href="#rfc2396">[IETF RFC 2396]</a>, except for the number sign
|
||
(<code>#</code>) and percent sign (<code>%</code>) characters and the square
|
||
bracket characters re-allowed in <a href="#rfc2732">[IETF RFC 2732]</a>. Disallowed characters
|
||
must be escaped as follows:</p></div>
|
||
<div class="diff-add"><ol>
|
||
<li><p>Each disallowed character is converted to UTF-8 <a href="#rfc2279">[IETF RFC 2279]</a>
|
||
as one or more bytes.</p></li>
|
||
<li><p>Any octets corresponding to a disallowed character are escaped with
|
||
the URI escaping mechanism (that is, converted to <code>%</code><var>HH</var>,
|
||
where HH is the hexadecimal notation of the byte value).</p></li>
|
||
<li><p>The original character is replaced by the resulting character sequence.</p>
|
||
</li>
|
||
</ol></div>
|
||
<p>[<a name="dt-pubid" title="Public identifier">Definition</a>: In addition to a system
|
||
identifier, an external identifier may include a <b>public identifier</b>.]
|
||
An XML processor attempting to retrieve the entity's content may use the public
|
||
identifier to try to generate an alternative <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E88">[E88]</a>URI reference</span>.
|
||
If the processor is unable to do so, it must use the <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E88">[E88]</a>URI
|
||
reference</span> specified in the system literal. Before a match is attempted,
|
||
all strings of white space in the public identifier must be normalized to
|
||
single space characters (#x20), and leading and trailing white space must
|
||
be removed.</p>
|
||
<p>Examples of external entity declarations:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ENTITY open-hatch
|
||
SYSTEM "http://www.textuality.com/boilerplate/OpenHatch.xml">
|
||
<!ENTITY open-hatch
|
||
PUBLIC "-//Textuality//TEXT Standard open-hatch boilerplate//EN"
|
||
"http://www.textuality.com/boilerplate/OpenHatch.xml">
|
||
<!ENTITY hatch-pic
|
||
SYSTEM "../grafix/OpenHatch.gif"
|
||
NDATA gif ></pre></td></tr></table>
|
||
</div>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="TextEntities"></a>4.3 Parsed Entities</h3>
|
||
<div class="div3">
|
||
|
||
<h4><a name="sec-TextDecl"></a>4.3.1 The Text Declaration</h4>
|
||
<p>External parsed entities <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E107">[E107]</a>should</span> each begin with a <b>text declaration</b>.</p>
|
||
|
||
<h5>Text Declaration</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-TextDecl"></a>[77]<5D><><EFBFBD></td><td><code>TextDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<?xml' <a href="#NT-VersionInfo">VersionInfo</a>? <a href="#NT-EncodingDecl">EncodingDecl</a> <a href="#NT-S">S</a>? '?>'</code></td><xsltdebug></xsltdebug></tr>
|
||
</tbody></table>
|
||
<p>The text declaration must be provided literally, not by reference to a
|
||
parsed entity. No text declaration may appear at any position other than the
|
||
beginning of an external parsed entity. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E94">[E94]</a>The text declaration
|
||
in an external parsed entity is not considered part of its <a title="Replacement Text" href="#dt-repltext">replacement
|
||
text</a>.</span></p>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="wf-entities"></a>4.3.2 Well-Formed Parsed Entities</h4>
|
||
<p>The document entity is well-formed if it matches the production labeled <a href="#NT-document">document</a>. An external general parsed entity is well-formed
|
||
if it matches the production labeled <a href="#NT-extParsedEnt">extParsedEnt</a>. <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</a>All
|
||
external parameter entities are well-formed by definition.</span></p>
|
||
|
||
<h5>Well-Formed External Parsed Entity</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-extParsedEnt"></a>[78]<5D><><EFBFBD></td><td><code>extParsedEnt</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-TextDecl">TextDecl</a>? <a href="#NT-content">content</a></code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td class="diff-del"><a name="NT-extPE"></a>[79]<5D><><EFBFBD></td><td class="diff-del"><code>extPE</code></td><td class="diff-del"><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td class="diff-del"><code><a href="#NT-TextDecl">TextDecl</a>? <a href="#NT-extSubsetDecl">extSubsetDecl</a></code></td><xsltdebug></xsltdebug><td class="diff-del"><i>/* <a href="http://www.w3.org/XML/xml-19980210-errata#E109">[E109]</a> */</i></td></tr></tbody></table>
|
||
<p>An internal general parsed entity is well-formed if its replacement text
|
||
matches the production labeled <a href="#NT-content">content</a>. All internal
|
||
parameter entities are well-formed by definition.</p>
|
||
<p>A consequence of well-formedness in entities is that the logical and physical
|
||
structures in an XML document are properly nested; no <a title="Start-Tag" href="#dt-stag">start-tag</a>, <a title="End Tag" href="#dt-etag">end-tag</a>, <a title="Empty" href="#dt-empty">empty-element tag</a>, <a title="Element" href="#dt-element">element</a>, <a title="Comment" href="#dt-comment">comment</a>, <a title="Processing instruction" href="#dt-pi">processing instruction</a>, <a title="Character Reference" href="#dt-charref">character
|
||
reference</a>, or <a title="Entity Reference" href="#dt-entref">entity reference</a>
|
||
can begin in one entity and end in another.</p>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="charencoding"></a>4.3.3 Character Encoding in Entities</h4>
|
||
<p>Each external parsed entity in an XML document may use a different encoding
|
||
for its characters. All XML processors must be able to read entities in <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E56">[E56]</a>both
|
||
the UTF-8 and UTF-16 encodings.</span> <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E77">[E77]</a>The terms "UTF-8"
|
||
and "UTF-16" in this specification do not apply to character
|
||
encodings with any other labels, even if the encodings or labels are very
|
||
similar to UTF-8 or UTF-16.</span></p>
|
||
<p>Entities encoded in UTF-16 must begin with the Byte Order Mark described
|
||
by <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</a>Annex
|
||
F of <a href="#ISO10646">[ISO/IEC 10646]</a>, Annex H of <a href="#ISO10646-2000">[ISO/IEC 10646-2000]</a>, section
|
||
2.4 of <a href="#Unicode">[Unicode]</a>, and section 2.7 of <a href="#Unicode3">[Unicode3]</a></span>
|
||
(the ZERO WIDTH NO-BREAK SPACE character, #xFEFF). This is an encoding signature,
|
||
not part of either the markup or the character data of the XML document. XML
|
||
processors must be able to use this character to differentiate between UTF-8
|
||
and UTF-16 encoded documents.</p>
|
||
<p>Although an XML processor is required to read only entities in the UTF-8
|
||
and UTF-16 encodings, it is recognized that other encodings are used around
|
||
the world, and it may be desired for XML processors to read entities that
|
||
use them. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E47">[E47]</a>In
|
||
the absence of external character encoding information (such as MIME headers),</span>
|
||
parsed entities which are stored in an encoding other than UTF-8 or UTF-16
|
||
must begin with a text declaration <span class="diff-add">(see <a href="#sec-TextDecl"><b>4.3.1 The Text Declaration</b></a>) </span>containing
|
||
an encoding declaration:</p>
|
||
|
||
<h5>Encoding Declaration</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-EncodingDecl"></a>[80]<5D><><EFBFBD></td><td><code>EncodingDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-S">S</a> 'encoding' <a href="#NT-Eq">Eq</a>
|
||
('"' <a href="#NT-EncName">EncName</a> '"' | "'" <a href="#NT-EncName">EncName</a>
|
||
"'" ) </code></td><xsltdebug></xsltdebug></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-EncName"></a>[81]<5D><><EFBFBD></td><td><code>EncName</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>[A-Za-z] ([A-Za-z0-9._] | '-')*</code></td><xsltdebug></xsltdebug><td><i>/* Encoding
|
||
name contains only Latin characters */</i></td></tr></tbody></table>
|
||
<p>In the <a title="Document Entity" href="#dt-docent">document entity</a>, the encoding
|
||
declaration is part of the <a title="XML Declaration" href="#dt-xmldecl">XML declaration</a>.
|
||
The <a href="#NT-EncName">EncName</a> is the name of the encoding used.</p>
|
||
|
||
<p>In an encoding declaration, the values "<code>UTF-8</code>", "<code>UTF-16</code>", "<code>ISO-10646-UCS-2</code>", and "<code>ISO-10646-UCS-4</code>" should be used
|
||
for the various encodings and transformations of Unicode / ISO/IEC 10646,
|
||
the values "<code>ISO-8859-1</code>", "<code>ISO-8859-2</code>",
|
||
... <a href="http://www.w3.org/XML/xml-19980210-errata#E106">[E106]</a><span class="diff-chg">"<code>ISO-8859-</code><var>n</var>" (where <var>n</var>
|
||
is the part number)</span> should be used for the parts of ISO 8859, and
|
||
the values "<code>ISO-2022-JP</code>", "<code>Shift_JIS</code>",
|
||
and "<code>EUC-JP</code>" should be used for the various encoded
|
||
forms of JIS X-0208-1997. <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E57">[E57]</a>It
|
||
is recommended that character encodings registered (as <em>charset</em>s)
|
||
with the Internet Assigned Numbers Authority <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E58">[E58]</a><a href="#IANA">[IANA-CHARSETS]</a></span>,
|
||
other than those just listed, be referred to using their registered names;
|
||
other encodings should use names starting with an "x-" prefix.
|
||
XML processors should match character encoding names in a case-insensitive
|
||
way and should either interpret an IANA-registered name as the encoding registered
|
||
at IANA for that name or treat it as unknown (processors are, of course, not
|
||
required to support all IANA-registered encodings).</span></p>
|
||
<p>In the absence of information provided by an external transport protocol
|
||
(e.g. HTTP or MIME), it is an <a title="Error" href="#dt-error">error</a> for
|
||
an entity including an encoding declaration to be presented to the XML processor
|
||
in an encoding other than that named in the declaration, <span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E5">[E5]</a>for
|
||
an encoding declaration to occur other than at the beginning of an external
|
||
entity, </span>or for an entity which begins with neither a Byte Order Mark
|
||
nor an encoding declaration to use an encoding other than UTF-8. Note that
|
||
since ASCII is a subset of UTF-8, ordinary ASCII entities do not strictly
|
||
need an encoding declaration.</p>
|
||
<div class="diff-add"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E5">[E5]</a>It
|
||
is <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E36">[E36]</a>a
|
||
fatal</span> error for a <a href="#NT-TextDecl">TextDecl</a> to occur other
|
||
than at the beginning of an external entity.</p></div>
|
||
<p>It is a <a title="Fatal Error" href="#dt-fatal">fatal error</a> when an XML processor
|
||
encounters an entity with an encoding that it is unable to process. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E79">[E79]</a>It
|
||
is a fatal error if an XML entity is determined (via default, encoding declaration,
|
||
or higher-level protocol) to be in a certain encoding but contains octet sequences
|
||
that are not legal in that encoding. It is also a fatal error if an XML entity
|
||
contains no encoding declaration and its content is not legal UTF-8 or UTF-16.</span></p>
|
||
<p>Examples of <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E23">[E23]</a>text
|
||
declarations containing </span>encoding declarations:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><?xml encoding='UTF-8'?>
|
||
<?xml encoding='EUC-JP'?></pre></td></tr></table>
|
||
</div>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="entproc"></a>4.4 XML Processor Treatment of Entities and References</h3>
|
||
<p>The table below summarizes the contexts in which character references,
|
||
entity references, and invocations of unparsed entities might appear and the
|
||
required behavior of an <a title="XML Processor" href="#dt-xml-proc">XML processor</a>
|
||
in each case. The labels in the leftmost column describe the recognition context: </p><dl>
|
||
<dt class="label">Reference in Content</dt>
|
||
<dd>
|
||
<p>as a reference anywhere after the <a title="Start-Tag" href="#dt-stag">start-tag</a>
|
||
and before the <a title="End Tag" href="#dt-etag">end-tag</a> of an element; corresponds
|
||
to the nonterminal <a href="#NT-content">content</a>.</p>
|
||
</dd>
|
||
<dt class="label">Reference in Attribute Value</dt>
|
||
<dd>
|
||
<p>as a reference within either the value of an attribute in a <a title="Start-Tag" href="#dt-stag">start-tag</a>,
|
||
or a default value in an <a title="Attribute-List Declaration" href="#dt-attdecl">attribute declaration</a>;
|
||
corresponds to the nonterminal <a href="#NT-AttValue">AttValue</a>.</p>
|
||
</dd>
|
||
<dt class="label">Occurs as Attribute Value</dt>
|
||
<dd>
|
||
<p>as a <a href="#NT-Name">Name</a>, not a reference, appearing either as
|
||
the value of an attribute which has been declared as type <b>ENTITY</b>,
|
||
or as one of the space-separated tokens in the value of an attribute which
|
||
has been declared as type <b>ENTITIES</b>.</p>
|
||
</dd>
|
||
<dt class="label">Reference in Entity Value</dt>
|
||
<dd>
|
||
<p>as a reference within a parameter or internal entity's <a title="Literal Entity Value" href="#dt-litentval">literal
|
||
entity value</a> in the entity's declaration; corresponds to the nonterminal <a href="#NT-EntityValue">EntityValue</a>.</p>
|
||
</dd>
|
||
<dt class="label">Reference in DTD</dt>
|
||
<dd>
|
||
<div class="diff-chg"><p><a href="http://www.w3.org/XML/xml-19980210-errata#E90">[E90]</a>as
|
||
a reference within either the internal or external subsets of the <a title="Document Type Declaration" href="#dt-doctype">DTD</a>, but outside of an <a href="#NT-EntityValue">EntityValue</a>, <a href="#NT-AttValue">AttValue</a>, <a href="#NT-PI">PI</a>, <a href="#NT-Comment">Comment</a>, <a href="#NT-SystemLiteral">SystemLiteral</a>, <a href="#NT-PubidLiteral">PubidLiteral</a>,
|
||
or the contents of an ignored conditional section (see <a href="#sec-condition-sect"><b>3.4 Conditional Sections</b></a>).</p></div>
|
||
<p>.</p>
|
||
</dd>
|
||
</dl><p></p>
|
||
<table border="1" frame="border" cellpadding="7"><tbody align="center"><tr>
|
||
<td rowspan="2" colspan="1"></td><td colspan="4" align="center" valign="bottom" rowspan="1">Entity
|
||
Type</td><td rowspan="2" align="center" colspan="1">Character</td></tr><tr align="center" valign="bottom"><td rowspan="1" colspan="1">Parameter</td><td rowspan="1" colspan="1">Internal General</td><td rowspan="1" colspan="1">External Parsed
|
||
General</td><td rowspan="1" colspan="1">Unparsed</td></tr><tr align="center" valign="middle"><td align="right" rowspan="1" colspan="1">Reference
|
||
in Content</td><td rowspan="1" colspan="1"><a href="#not-recognized"><cite>Not recognized</cite></a></td>
|
||
<td rowspan="1" colspan="1"><a href="#included"><cite>Included</cite></a></td><td rowspan="1" colspan="1"><a href="#include-if-valid"><cite>Included
|
||
if validating</cite></a></td><td rowspan="1" colspan="1"><a href="#forbidden"><cite>Forbidden</cite></a></td>
|
||
<td rowspan="1" colspan="1"><a href="#included"><cite>Included</cite></a></td></tr><tr align="center" valign="middle"><td align="right" rowspan="1" colspan="1">Reference in Attribute Value</td><td rowspan="1" colspan="1"><a href="#not-recognized"><cite>Not recognized</cite></a></td><td rowspan="1" colspan="1"><a href="#inliteral"><cite>Included
|
||
in literal</cite></a></td><td rowspan="1" colspan="1"><a href="#forbidden"><cite>Forbidden</cite></a></td>
|
||
<td rowspan="1" colspan="1"><a href="http://www.w3.org/XML/xml-19980210-errata#E51">[E51]</a><div class="diff-chg"><a href="#forbidden"><cite>Forbidden</cite></a></div></td><td rowspan="1" colspan="1"><a href="#included"><cite>Included</cite></a></td>
|
||
</tr><tr align="center" valign="middle"><td align="right" rowspan="1" colspan="1">Occurs as Attribute
|
||
Value</td><td rowspan="1" colspan="1"><a href="#not-recognized"><cite>Not recognized</cite></a></td>
|
||
<td rowspan="1" colspan="1"><a href="#forbidden"><cite>Forbidden</cite></a></td><td rowspan="1" colspan="1"><a href="http://www.w3.org/XML/xml-19980210-errata#E51">[E51]</a><div class="diff-chg"><a href="#forbidden"><cite>Forbidden</cite></a></div></td><td rowspan="1" colspan="1"><a href="#notify"><cite>Notify</cite></a></td>
|
||
<td rowspan="1" colspan="1"><a href="http://www.w3.org/XML/xml-19980210-errata#E51">[E51]</a><div class="diff-chg"><a href="#not-recognized"><cite>Not recognized</cite></a></div></td></tr><tr align="center" valign="middle"><td align="right" rowspan="1" colspan="1">Reference in EntityValue</td><td rowspan="1" colspan="1"><a href="#inliteral"><cite>Included in literal</cite></a></td><td rowspan="1" colspan="1"><a href="#bypass"><cite>Bypassed</cite></a></td>
|
||
<td rowspan="1" colspan="1"><a href="#bypass"><cite>Bypassed</cite></a></td><td rowspan="1" colspan="1"><a href="#forbidden"><cite>Forbidden</cite></a></td>
|
||
<td rowspan="1" colspan="1"><a href="#included"><cite>Included</cite></a></td></tr><tr align="center" valign="middle"><td align="right" rowspan="1" colspan="1">Reference in DTD</td><td rowspan="1" colspan="1"><a href="#as-PE"><cite>Included
|
||
as PE</cite></a></td><td rowspan="1" colspan="1"><a href="#forbidden"><cite>Forbidden</cite></a></td>
|
||
<td rowspan="1" colspan="1"><a href="#forbidden"><cite>Forbidden</cite></a></td><td rowspan="1" colspan="1"><a href="#forbidden"><cite>Forbidden</cite></a></td>
|
||
<td rowspan="1" colspan="1"><a href="#forbidden"><cite>Forbidden</cite></a></td></tr></tbody></table>
|
||
<div class="div3">
|
||
|
||
<h4><a name="not-recognized"></a>4.4.1 Not Recognized</h4>
|
||
<p>Outside the DTD, the <code>%</code> character has no special significance;
|
||
thus, what would be parameter entity references in the DTD are not recognized
|
||
as markup in <a href="#NT-content">content</a>. Similarly, the names of unparsed
|
||
entities are not recognized except when they appear in the value of an appropriately
|
||
declared attribute.</p>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="included"></a>4.4.2 Included</h4>
|
||
<p>[<a name="dt-include" title="Include">Definition</a>: An entity is <b>included</b>
|
||
when its <a title="Replacement Text" href="#dt-repltext">replacement text</a> is retrieved
|
||
and processed, in place of the reference itself, as though it were part of
|
||
the document at the location the reference was recognized.] The replacement
|
||
text may contain both <a title="Character Data" href="#dt-chardata">character data</a>
|
||
and (except for parameter entities) <a title="Markup" href="#dt-markup">markup</a>,
|
||
which must be recognized in the usual way<span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E65">[E65]</a>, except that
|
||
the replacement text of entities used to escape markup delimiters (the entities <code>amp</code>,
|
||
<code>lt</code>,
|
||
<code>gt</code>,
|
||
<code>apos</code>,
|
||
<code>quot</code>)
|
||
is always treated as data</span>. (The string "<code>AT&amp;T;</code>"
|
||
expands to "<code>AT&T;</code>" and the remaining ampersand
|
||
is not recognized as an entity-reference delimiter.) A character reference
|
||
is <b>included</b> when the indicated character is processed in place
|
||
of the reference itself. </p>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="include-if-valid"></a>4.4.3 Included If Validating</h4>
|
||
<p>When an XML processor recognizes a reference to a parsed entity, in order
|
||
to <a title="Validity" href="#dt-valid">validate</a> the document, the processor
|
||
must <a title="Include" href="#dt-include">include</a> its replacement text. If
|
||
the entity is external, and the processor is not attempting to validate the
|
||
XML document, the processor <a title="May" href="#dt-may">may</a>, but need
|
||
not, include the entity's replacement text. If a non-validating <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E95">[E95]</a>processor</span>
|
||
does not include the replacement text, it must inform the application that
|
||
it recognized, but did not read, the entity.</p>
|
||
<p>This rule is based on the recognition that the automatic inclusion provided
|
||
by the SGML and XML entity mechanism, primarily designed to support modularity
|
||
in authoring, is not necessarily appropriate for other applications, in particular
|
||
document browsing. Browsers, for example, when encountering an external parsed
|
||
entity reference, might choose to provide a visual indication of the entity's
|
||
presence and retrieve it for display only on demand.</p>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="forbidden"></a>4.4.4 Forbidden</h4>
|
||
<p>The following are forbidden, and constitute <a title="Fatal Error" href="#dt-fatal">fatal</a>
|
||
errors:</p>
|
||
<ul>
|
||
<li><p>the appearance of a reference to an <a title="Unparsed Entity" href="#dt-unparsed">unparsed
|
||
entity</a>.</p></li>
|
||
<li><p>the appearance of any character or general-entity reference in the
|
||
DTD except within an <a href="#NT-EntityValue">EntityValue</a> or <a href="#NT-AttValue">AttValue</a>.</p>
|
||
</li>
|
||
<li><p>a reference to an external entity in an attribute value.</p></li>
|
||
</ul>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="inliteral"></a>4.4.5 Included in Literal</h4>
|
||
<p>When an <a title="Entity Reference" href="#dt-entref">entity reference</a> appears in
|
||
an attribute value, or a parameter entity reference appears in a literal entity
|
||
value, its <a title="Replacement Text" href="#dt-repltext">replacement text</a> is processed
|
||
in place of the reference itself as though it were part of the document at
|
||
the location the reference was recognized, except that a single or double
|
||
quote character in the replacement text is always treated as a normal data
|
||
character and will not terminate the literal. For example, this is well-formed:</p>
|
||
<div class="diff-chg"><table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td class="diff-chg"><pre><!-- <a href="http://www.w3.org/XML/xml-19980210-errata#E4">[E4]</a> -->
|
||
<!ENTITY % YN '"Yes"' >
|
||
<!ENTITY WhatHeSaid "He said %YN;" ></pre></td></tr></table></div>
|
||
<p>while this is not:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ENTITY EndAttr "27'" >
|
||
<element attribute='a-&EndAttr;></pre></td></tr></table>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="notify"></a>4.4.6 Notify</h4>
|
||
<p>When the name of an <a title="Unparsed Entity" href="#dt-unparsed">unparsed entity</a>
|
||
appears as a token in the value of an attribute of declared type <b>ENTITY</b>
|
||
or <b>ENTITIES</b>, a validating processor must inform the application of
|
||
the <a title="System Identifier" href="#dt-sysid">system</a> and <a title="Public identifier" href="#dt-pubid">public</a>
|
||
(if any) identifiers for both the entity and its associated <a title="Notation" href="#dt-notation">notation</a>.</p>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="bypass"></a>4.4.7 Bypassed</h4>
|
||
<p>When a general entity reference appears in the <a href="#NT-EntityValue">EntityValue</a>
|
||
in an entity declaration, it is bypassed and left as is.</p>
|
||
</div>
|
||
<div class="div3">
|
||
|
||
<h4><a name="as-PE"></a>4.4.8 Included as PE</h4>
|
||
<p>Just as with external parsed entities, parameter entities need only be <a href="#include-if-valid"><cite>included if validating</cite></a>. When a parameter-entity
|
||
reference is recognized in the DTD and included, its <a title="Replacement Text" href="#dt-repltext">replacement
|
||
text</a> is enlarged by the attachment of one leading and one following
|
||
space (#x20) character; the intent is to constrain the replacement text of
|
||
parameter entities to contain an integral number of grammatical tokens in
|
||
the DTD. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E96">[E96]</a>This
|
||
behavior does not apply to parameter entity references within entity values;
|
||
these are described in <a href="#inliteral"><b>4.4.5 Included in Literal</b></a>.</span></p>
|
||
</div>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="intern-replacement"></a>4.5 Construction of Internal Entity Replacement Text</h3>
|
||
<p>In discussing the treatment of internal entities, it is useful to distinguish
|
||
two forms of the entity's value. [<a name="dt-litentval" title="Literal Entity Value">Definition</a>: The <b>literal
|
||
entity value</b> is the quoted string actually present in the entity declaration,
|
||
corresponding to the non-terminal <a href="#NT-EntityValue">EntityValue</a>.] [<a name="dt-repltext" title="Replacement Text">Definition</a>: The <b>replacement text</b>
|
||
is the content of the entity, after replacement of character references and
|
||
parameter-entity references.]</p>
|
||
<p>The literal entity value as given in an internal entity declaration (<a href="#NT-EntityValue">EntityValue</a>) may contain character, parameter-entity,
|
||
and general-entity references. Such references must be contained entirely
|
||
within the literal entity value. The actual replacement text that is <a title="Include" href="#dt-include">included</a> as described above must contain the <em>replacement
|
||
text</em> of any parameter entities referred to, and must contain the character
|
||
referred to, in place of any character references in the literal entity value;
|
||
however, general-entity references must be left as-is, unexpanded. For example,
|
||
given the following declarations:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ENTITY % pub "&#xc9;ditions Gallimard" >
|
||
<!ENTITY rights "All rights reserved" >
|
||
<!ENTITY book "La Peste: Albert Camus,
|
||
&#xA9; 1947 %pub;. &rights;" ></pre></td></tr></table>
|
||
<p>then the replacement text for the entity "<code>book</code>"
|
||
is:</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre>La Peste: Albert Camus,
|
||
<EFBFBD> 1947 <20>ditions Gallimard. &rights;</pre></td></tr></table>
|
||
<p>The general-entity reference "<code>&rights;</code>" would
|
||
be expanded should the reference "<code>&book;</code>" appear
|
||
in the document's content or an attribute value.</p>
|
||
<p>These simple rules may have complex interactions; for a detailed discussion
|
||
of a difficult example, see <a href="#sec-entexpand"><b>D Expansion of Entity and Character References</b></a>.</p>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-predefined-ent"></a>4.6 Predefined Entities</h3>
|
||
<p>[<a name="dt-escape" title="escape">Definition</a>: Entity and character references can
|
||
both be used to <b>escape</b> the left angle bracket, ampersand, and
|
||
other delimiters. A set of general entities (<code>amp</code>,
|
||
<code>lt</code>,
|
||
<code>gt</code>,
|
||
<code>apos</code>,
|
||
<code>quot</code>) is specified for
|
||
this purpose. Numeric character references may also be used; they are expanded
|
||
immediately when recognized and must be treated as character data, so the
|
||
numeric character references "<code>&#60;</code>" and "<code>&#38;</code>"
|
||
may be used to escape <code><</code> and <code>&</code> when they occur
|
||
in character data.]</p>
|
||
<p>All XML processors must recognize these entities whether they are declared
|
||
or not. <a title="For interoperability" href="#dt-interop">For interoperability</a>, valid XML
|
||
documents should declare these entities, like any others, before using them. <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E80">[E80]</a>If
|
||
the entities <code>lt</code> or <code>amp</code> are declared, they must be
|
||
declared as internal entities whose replacement text is a character reference
|
||
to the <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E103">[E103]</a>respective
|
||
character (less-than sign or ampersand)</span> being escaped; the double
|
||
escaping is required for these entities so that references to them produce
|
||
a well-formed result. If the entities <code>gt</code>, <code>apos</code>,
|
||
or <code>quot</code> are declared, they must be declared as internal entities
|
||
whose replacement text is the single character being escaped (or a character
|
||
reference to that character; the double escaping here is unnecessary but harmless).
|
||
For example:</span></p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ENTITY lt "&#38;#60;">
|
||
<!ENTITY gt "&#62;">
|
||
<!ENTITY amp "&#38;#38;">
|
||
<!ENTITY apos "&#39;">
|
||
<!ENTITY quot "&#34;"></pre></td></tr></table>
|
||
<div class="diff-del"><p>Note that the <code><</code> and <code>&</code> characters
|
||
in the declarations of "<code>lt</code>" and "<code>amp</code>"
|
||
are doubly escaped to meet the requirement that entity replacement be well-formed.</p></div>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="Notations"></a>4.7 Notation Declarations</h3>
|
||
<p>[<a name="dt-notation" title="Notation">Definition</a>: <b>Notations</b> identify
|
||
by name the format of <a title="External Entity" href="#dt-extent">unparsed entities</a>,
|
||
the format of elements which bear a notation attribute, or the application
|
||
to which a <a title="Processing instruction" href="#dt-pi">processing instruction</a> is addressed.]</p>
|
||
<p>[<a name="dt-notdecl" title="Notation Declaration">Definition</a>: <b>Notation declarations</b>
|
||
provide a name for the notation, for use in entity and attribute-list declarations
|
||
and in attribute specifications, and an external identifier for the notation
|
||
which may allow an XML processor or its client application to locate a helper
|
||
application capable of processing data in the given notation.]</p>
|
||
|
||
<h5>Notation Declarations</h5><table class="scrap" summary="Scrap"><tbody><tr valign="baseline"><td><a name="NT-NotationDecl"></a>[82]<5D><><EFBFBD></td><td><code>NotationDecl</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'<!NOTATION' <a href="#NT-S">S</a> <a href="#NT-Name">Name</a> <a href="#NT-S">S</a> (<a href="#NT-ExternalID">ExternalID</a> | <a href="#NT-PublicID">PublicID</a>) <a href="#NT-S">S</a>? '>'</code></td><xsltdebug></xsltdebug><td class="diff-add"><a href="#UniqueNotationName">[VC: Unique
|
||
Notation Name]</a></td></tr></tbody><tbody><tr valign="baseline"><td><a name="NT-PublicID"></a>[83]<5D><><EFBFBD></td><td><code>PublicID</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>'PUBLIC' <a href="#NT-S">S</a> <a href="#NT-PubidLiteral">PubidLiteral</a> </code></td><xsltdebug></xsltdebug></tr></tbody></table>
|
||
<div class="diff-add"><div class="constraint"><p class="prefix"><a name="UniqueNotationName"></a><b>Validity constraint: <a href="http://www.w3.org/XML/xml-19980210-errata#E22">[E22]</a>Unique
|
||
Notation Name</b></p><p>Only one notation declaration can declare a given <a href="#NT-Name">Name</a>.</p>
|
||
</div></div>
|
||
<p>XML processors must provide applications with the name and external identifier(s)
|
||
of any notation declared and referred to in an attribute value, attribute
|
||
definition, or entity declaration. They may additionally resolve the external
|
||
identifier into the <a title="System Identifier" href="#dt-sysid">system identifier</a>, file
|
||
name, or other information needed to allow the application to call a processor
|
||
for data in the notation described. (It is not an error, however, for XML
|
||
documents to declare and refer to notations for which notation-specific applications
|
||
are not available on the system where the XML processor or application is
|
||
running.)</p>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-doc-entity"></a>4.8 Document Entity</h3>
|
||
<p>[<a name="dt-docent" title="Document Entity">Definition</a>: The <b>document entity</b>
|
||
serves as the root of the entity tree and a starting-point for an <a title="XML Processor" href="#dt-xml-proc">XML processor</a>.] This specification does
|
||
not specify how the document entity is to be located by an XML processor;
|
||
unlike other entities, the document entity has no name and might well appear
|
||
on a processor input stream without any identification at all.</p>
|
||
</div>
|
||
</div>
|
||
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-conformance"></a>5 Conformance</h2>
|
||
<div class="div2">
|
||
|
||
<h3><a name="proc-types"></a>5.1 Validating and Non-Validating Processors</h3>
|
||
<p>Conforming <a title="XML Processor" href="#dt-xml-proc">XML processors</a> fall into
|
||
two classes: validating and non-validating.</p>
|
||
<p>Validating and non-validating processors alike must report violations of
|
||
this specification's well-formedness constraints in the content of the <a title="Document Entity" href="#dt-docent">document entity</a> and any other <a title="Text Entity" href="#dt-parsedent">parsed
|
||
entities</a> that they read.</p>
|
||
<p>[<a name="dt-validating" title="Validating Processor">Definition</a>: <b>Validating
|
||
processors</b> must<span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E21">[E21]</a>,
|
||
at user option,</span> report violations of the constraints expressed by
|
||
the declarations in the <a title="Document Type Declaration" href="#dt-doctype">DTD</a>, and failures
|
||
to fulfill the validity constraints given in this specification.]
|
||
To accomplish this, validating XML processors must read and process the entire
|
||
DTD and all external parsed entities referenced in the document.</p>
|
||
<p>Non-validating processors are required to check only the <a title="Document Entity" href="#dt-docent">document
|
||
entity</a>, including the entire internal DTD subset, for well-formedness. [<a name="dt-use-mdecl" title="Process Declarations">Definition</a>: While they are not required
|
||
to check the document for validity, they are required to <b>process</b>
|
||
all the declarations they read in the internal DTD subset and in any parameter
|
||
entity that they read, up to the first reference to a parameter entity that
|
||
they do <em>not</em> read; that is to say, they must use the information
|
||
in those declarations to <a href="#AVNormalize"><cite>normalize</cite></a>
|
||
attribute values, <a href="#included"><cite>include</cite></a> the replacement
|
||
text of internal entities, and supply <a href="#sec-attr-defaults"><cite>default
|
||
attribute values</cite></a>.] <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E33">[E33]</a>Except when <code>standalone="yes"</code>, </span>they
|
||
must not <a title="Process Declarations" href="#dt-use-mdecl">process</a> <a title="entity declaration" href="#dt-entdecl">entity
|
||
declarations</a> or <a title="Attribute-List Declaration" href="#dt-attdecl">attribute-list declarations</a>
|
||
encountered after a reference to a parameter entity that is not read, since
|
||
the entity may have contained overriding declarations.</p>
|
||
</div>
|
||
<div class="div2">
|
||
|
||
<h3><a name="safe-behavior"></a>5.2 Using XML Processors</h3>
|
||
<p>The behavior of a validating XML processor is highly predictable; it must
|
||
read every piece of a document and report all well-formedness and validity
|
||
violations. Less is required of a non-validating processor; it need not read
|
||
any part of the document other than the document entity. This has two effects
|
||
that may be important to users of XML processors:</p>
|
||
<ul>
|
||
<li><p>Certain well-formedness errors, specifically those that require reading
|
||
external entities, may not be detected by a non-validating processor. Examples
|
||
include the constraints entitled <a href="#wf-entdeclared"><cite>Entity Declared</cite></a>, <a href="#textent"><cite>Parsed Entity</cite></a>, and <a href="#norecursion"><cite>No
|
||
Recursion</cite></a>, as well as some of the cases described as <a href="#forbidden"><cite>forbidden</cite></a> in <a href="#entproc"><b>4.4 XML Processor Treatment of Entities and References</b></a>.</p></li>
|
||
<li><p>The information passed from the processor to the application may
|
||
vary, depending on whether the processor reads parameter and external entities.
|
||
For example, a non-validating processor may not <a href="#AVNormalize"><cite>normalize</cite></a>
|
||
attribute values, <a href="#included"><cite>include</cite></a> the replacement
|
||
text of internal entities, or supply <a href="#sec-attr-defaults"><cite>default
|
||
attribute values</cite></a>, where doing so depends on having read declarations
|
||
in external or parameter entities.</p></li>
|
||
</ul>
|
||
<p>For maximum reliability in interoperating between different XML processors,
|
||
applications which use non-validating processors should not rely on any behaviors
|
||
not required of such processors. Applications which require facilities such
|
||
as the use of default attributes or internal entities which are declared in
|
||
external entities should use validating XML processors.</p>
|
||
</div>
|
||
</div>
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-notation"></a>6 Notation</h2>
|
||
<p>The formal grammar of XML is given in this specification using a simple
|
||
Extended Backus-Naur Form (EBNF) notation. Each rule in the grammar defines
|
||
one symbol, in the form</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre>symbol ::= expression</pre></td></tr></table>
|
||
<p>Symbols are written with an initial capital letter if they are <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E42">[E42]</a>the
|
||
start symbol of a regular language,</span> otherwise with an initial lower
|
||
case letter. Literal strings are quoted.</p>
|
||
<p>Within the expression on the right-hand side of a rule, the following expressions
|
||
are used to match strings of one or more characters: </p><dl>
|
||
<dt class="label"><code>#xN</code></dt>
|
||
<dd>
|
||
<p>where <code>N</code> is a hexadecimal integer, the expression matches the
|
||
character in ISO/IEC 10646 whose canonical (UCS-4) code value, when interpreted
|
||
as an unsigned binary number, has the value indicated. The number of leading
|
||
zeros in the <code>#xN</code> form is insignificant; the number of leading
|
||
zeros in the corresponding code value is governed by the character encoding
|
||
in use and is not significant for XML.</p>
|
||
</dd>
|
||
<dt class="label"><code>[a-zA-Z]</code>, <code>[#xN-#xN]</code></dt>
|
||
<dd>
|
||
<p>matches any <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E93">[E93]</a><a href="#NT-Char">Char</a></span> with a value in the range(s) indicated (inclusive).</p>
|
||
</dd>
|
||
<dt class="label"><span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E3">[E3]</a><code>[abc]</code>, <code>[#xN#xN#xN]</code></span></dt>
|
||
<dd><div class="diff-add">
|
||
<p>matches any <a href="#NT-Char">Char</a> with a value among the characters
|
||
enumerated. Enumerations and ranges can be mixed in one set of brackets.</p>
|
||
</div></dd>
|
||
<dt class="label"><code>[^a-z]</code>, <code>[^#xN-#xN]</code></dt>
|
||
<dd>
|
||
<p>matches any <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E93">[E93]</a><a href="#NT-Char">Char</a></span> with a value <em>outside</em> the range
|
||
indicated.</p>
|
||
</dd>
|
||
<dt class="label"><code>[^abc]</code>, <code>[^#xN#xN#xN]</code></dt>
|
||
<dd>
|
||
<p>matches any <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E93">[E93]</a><a href="#NT-Char">Char</a></span> with a value not among the characters given. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E3">[E3]</a>Enumerations
|
||
and ranges of forbidden values can be mixed in one set of brackets.</span></p>
|
||
</dd>
|
||
<dt class="label"><code>"string"</code></dt>
|
||
<dd>
|
||
<p>matches a literal string <a title="match" href="#dt-match">matching</a> that
|
||
given inside the double quotes.</p>
|
||
</dd>
|
||
<dt class="label"><code>'string'</code></dt>
|
||
<dd>
|
||
<p>matches a literal string <a title="match" href="#dt-match">matching</a> that
|
||
given inside the single quotes.</p>
|
||
</dd>
|
||
</dl><p> These symbols may be combined to match more complex patterns as follows,
|
||
where <code>A</code> and <code>B</code> represent simple expressions: </p><dl>
|
||
<dt class="label">(<code>expression</code>)</dt>
|
||
<dd>
|
||
<p><code>expression</code> is treated as a unit and may be combined as described
|
||
in this list.</p>
|
||
</dd>
|
||
<dt class="label"><code>A?</code></dt>
|
||
<dd>
|
||
<p>matches <code>A</code> or nothing; optional <code>A</code>.</p>
|
||
</dd>
|
||
<dt class="label"><code>A B</code></dt>
|
||
<dd>
|
||
<p>matches <code>A</code> followed by <code>B</code>. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E20">[E20]</a>This
|
||
operator has higher precedence than alternation; thus <code>A B | C D</code>
|
||
is identical to <code>(A B) | (C D)</code>.</span></p>
|
||
</dd>
|
||
<dt class="label"><code>A | B</code></dt>
|
||
<dd>
|
||
<p>matches <code>A</code> or <code>B</code> but not both.</p>
|
||
</dd>
|
||
<dt class="label"><code>A - B</code></dt>
|
||
<dd>
|
||
<p>matches any string that matches <code>A</code> but does not match <code>B</code>.</p>
|
||
</dd>
|
||
<dt class="label"><code>A+</code></dt>
|
||
<dd>
|
||
<p>matches one or more occurrences of <code>A</code>.<span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E20">[E20]</a>Concatenation
|
||
has higher precedence than alternation; thus <code>A+ | B+</code> is identical
|
||
to <code>(A+) | (B+)</code>.</span></p>
|
||
</dd>
|
||
<dt class="label"><code>A*</code></dt>
|
||
<dd>
|
||
<p>matches zero or more occurrences of <code>A</code>. <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E20">[E20]</a>Concatenation
|
||
has higher precedence than alternation; thus <code>A* | B*</code> is identical
|
||
to <code>(A*) | (B*)</code>.</span></p>
|
||
</dd>
|
||
</dl><p> Other notations used in the productions are: </p><dl>
|
||
<dt class="label"><code>/* ... */</code></dt>
|
||
<dd>
|
||
<p>comment.</p>
|
||
</dd>
|
||
<dt class="label"><code>[ wfc: ... ]</code></dt>
|
||
<dd>
|
||
<p>well-formedness constraint; this identifies by name a constraint on <a title="Well-Formed" href="#dt-wellformed">well-formed</a> documents associated with a production.</p>
|
||
</dd>
|
||
<dt class="label"><code>[ vc: ... ]</code></dt>
|
||
<dd>
|
||
<p>validity constraint; this identifies by name a constraint on <a title="Validity" href="#dt-valid">valid</a>
|
||
documents associated with a production.</p>
|
||
</dd>
|
||
</dl><p></p>
|
||
</div>
|
||
</div><div class="back">
|
||
|
||
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-bibliography"></a>A References</h2>
|
||
<div class="div2">
|
||
|
||
<h3><a name="sec-existing-stds"></a>A.1 Normative References</h3>
|
||
<dl>
|
||
<dt class="label"><span class="diff-chg"><a name="IANA"></a>IANA-CHARSETS</span></dt><dd><div class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E58">[E58]</a>(Internet
|
||
Assigned Numbers Authority) <cite>Official Names for Character Sets</cite>,
|
||
ed. Keld Simonsen et al. See <a href="ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets">ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets</a>. </div></dd>
|
||
<dt class="label"><a name="RFC1766"></a>IETF RFC 1766</dt><dd>IETF
|
||
(Internet Engineering Task Force). <cite>RFC 1766: Tags for the Identification
|
||
of Languages</cite>, ed. H. Alvestrand. 1995. (See <a href="http://www.ietf.org/rfc/rfc1766.txt">http://www.ietf.org/rfc/rfc1766.txt</a>.)</dd>
|
||
<dt class="label"><span class="diff-del"><a name="ISO639-old"></a>ISO 639</span></dt><dd><div class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E38">[E38]</a>
|
||
(International Organization for Standardization). <cite>ISO 639:1988 (E).
|
||
Code for the representation of names of languages.</cite> [Geneva]: International
|
||
Organization for Standardization, 1988.</div></dd>
|
||
<dt class="label"><span class="diff-del"><a name="ISO3166-old"></a>ISO 3166</span></dt><dd><div class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E38">[E38]</a>
|
||
(International Organization for Standardization). <cite>ISO 3166-1:1997
|
||
(E). Codes for the representation of names of countries and their subdivisions --
|
||
Part 1: Country codes</cite> [Geneva]: International Organization for
|
||
Standardization, 1997.</div></dd>
|
||
<dt class="label"><a name="ISO10646"></a>ISO/IEC 10646</dt><dd>ISO (International Organization for
|
||
Standardization). <cite>ISO/IEC 10646-1993 (E). Information technology --
|
||
Universal Multiple-Octet Coded Character Set (UCS) -- Part 1: Architecture
|
||
and Basic Multilingual Plane.</cite> [Geneva]: International Organization
|
||
for Standardization, 1993 (plus amendments AM 1 through AM 7).</dd>
|
||
<dt class="label"><span class="diff-add"><a name="ISO10646-2000"></a>ISO/IEC 10646-2000</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</a> ISO (International
|
||
Organization for Standardization). <cite>ISO/IEC 10646-1:2000. Information
|
||
technology -- Universal Multiple-Octet Coded Character Set (UCS) --
|
||
Part 1: Architecture and Basic Multilingual Plane.</cite> [Geneva]: International
|
||
Organization for Standardization, 2000.</div></dd>
|
||
<dt class="label"><a name="Unicode"></a>Unicode</dt><dd>The Unicode Consortium. <em>The Unicode
|
||
Standard, Version 2.0.</em> Reading, Mass.: Addison-Wesley Developers Press,
|
||
1996.</dd>
|
||
<dt class="label"><span class="diff-add"><a name="Unicode3"></a>Unicode3</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</a>
|
||
The Unicode Consortium. <em>The Unicode Standard, Version 3.0.</em> Reading,
|
||
Mass.: Addison-Wesley Developers Press, 2000. ISBN 0-201-61633-5.</div></dd>
|
||
</dl></div>
|
||
<div class="div2">
|
||
|
||
|
||
<h3><a name="null"></a>A.2 Other References</h3>
|
||
<dl>
|
||
<dt class="label"><a name="Aho"></a>Aho/Ullman</dt><dd>Aho, Alfred V., Ravi Sethi, and Jeffrey D.
|
||
Ullman. <cite>Compilers: Principles, Techniques, and Tools</cite>.
|
||
Reading: Addison-Wesley, 1986, rpt. corr. 1988.</dd>
|
||
<dt class="label"><a name="Berners-Lee"></a>Berners-Lee et al.</dt><dd> Berners-Lee, T., R. Fielding,
|
||
and L. Masinter. <cite>Uniform Resource Identifiers (URI): Generic Syntax
|
||
and Semantics</cite>. 1997. (Work in progress; see updates to RFC1738.)</dd>
|
||
<dt class="label"><span class="diff-chg"><a name="ABK"></a>Br<EFBFBD>ggemann-Klein</span></dt><dd><div class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E2">[E2]</a>Br<EFBFBD>ggemann-Klein,
|
||
Anne. Formal Models in Document Processing. Habilitationsschrift. Faculty
|
||
of Mathematics at the University of Freiburg, 1993. (See <a href="ftp://ftp.informatik.uni-freiburg.de/documents/papers/brueggem/habil.ps">ftp://ftp.informatik.uni-freiburg.de/documents/papers/brueggem/habil.ps</a>.)</div></dd>
|
||
<dt class="label"><span class="diff-chg"><a name="ABKDW"></a>Br<EFBFBD>ggemann-Klein and Wood</span></dt><dd><div class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E2">[E2]</a>Br<EFBFBD>ggemann-Klein,
|
||
Anne, and Derick Wood. <cite>Deterministic Regular Languages</cite>.
|
||
Universit<EFBFBD>t Freiburg, Institut f<>r Informatik, Bericht 38, Oktober 1991. Extended
|
||
abstract in A. Finkel, M. Jantzen, Hrsg., STACS 1992, S. 173-184. Springer-Verlag,
|
||
Berlin 1992. Lecture Notes in Computer Science 577. Full version titled <cite>One-Unambiguous
|
||
Regular Languages</cite> in Information and Computation 140 (2): 229-253,
|
||
February 1998.</div></dd>
|
||
<dt class="label"><a name="Clark"></a>Clark</dt><dd>James Clark. Comparison of SGML and XML. See <a href="http://www.w3.org/TR/NOTE-sgml-xml-971215">http://www.w3.org/TR/NOTE-sgml-xml-971215</a>. </dd>
|
||
<dt class="label"><span class="diff-add"><a name="IANA-LANGCODES"></a>IANA-LANGCODES</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E58">[E58]</a>(Internet
|
||
Assigned Numbers Authority) <cite>Registry of Language Tags</cite>,
|
||
ed. Keld Simonsen et al. (See <a href="http://www.isi.edu/in-notes/iana/assignments/languages/">http://www.isi.edu/in-notes/iana/assignments/languages/</a>.)</div></dd>
|
||
<dt class="label"><span class="diff-del"><a name="RFC1738"></a>IETF RFC1738</span></dt><dd><div class="diff-del">IETF
|
||
(Internet Engineering Task Force). <cite>RFC 1738: Uniform Resource Locators
|
||
(URL)</cite>, ed. T. Berners-Lee, L. Masinter, M. McCahill. 1994. (See <a href="http://www.ietf.org/rfc/rfc1738.txt">http://www.ietf.org/rfc/rfc1738.txt</a>.)</div></dd>
|
||
<dt class="label"><span class="diff-del"><a name="RFC1808"></a>IETF RFC1808</span></dt><dd><div class="diff-del">IETF
|
||
(Internet Engineering Task Force). <cite>RFC 1808: Relative Uniform Resource
|
||
Locators</cite>, ed. R. Fielding. 1995. (See <a href="http://www.ietf.org/rfc/rfc1808.txt">http://www.ietf.org/rfc/rfc1808.txt</a>.)</div></dd>
|
||
<dt class="label"><a name="RFC2141"></a>IETF RFC2141</dt><dd>IETF
|
||
(Internet Engineering Task Force). <em>RFC 2141: URN Syntax</em>, ed.
|
||
R. Moats. 1997. (See <a href="http://www.ietf.org/rfc/rfc2141.txt">http://www.ietf.org/rfc/rfc2141.txt</a>.)</dd>
|
||
<dt class="label"><span class="diff-add"><a name="rfc2279"></a>IETF RFC 2279</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E78">[E78]</a>IETF
|
||
(Internet Engineering Task Force). <cite>RFC 2279: UTF-8, a transformation
|
||
format of ISO 10646</cite>, <span class="diff-add">ed. F. Yergeau, </span>1998. (See <a href="http://www.ietf.org/rfc/rfc2279.txt">http://www.ietf.org/rfc/rfc2279.txt</a>.)</div></dd>
|
||
<dt class="label"><span class="diff-add"><a name="rfc2376"></a>IETF RFC 2376</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E48">[E48]</a>IETF
|
||
(Internet Engineering Task Force). <cite>RFC 2376: XML Media Types</cite>.
|
||
ed. E. Whitehead, M. Murata. 1998. (See <a href="http://www.ietf.org/rfc/rfc2376.txt">http://www.ietf.org/rfc/rfc2376.txt</a>.)</div></dd>
|
||
<dt class="label"><span class="diff-add"><a name="rfc2396"></a>IETF RFC 2396</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E66">[E66]</a>IETF
|
||
(Internet Engineering Task Force). <cite>RFC 2396: Uniform Resource Identifiers
|
||
(URI): Generic Syntax</cite>. T. Berners-Lee, R. Fielding, L. Masinter.
|
||
1998. (See <a href="http://www.ietf.org/rfc/rfc2396.txt">http://www.ietf.org/rfc/rfc2396.txt</a>.)</div></dd>
|
||
<dt class="label"><span class="diff-add"><a name="rfc2732"></a>IETF RFC 2732</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E66">[E66]</a>IETF
|
||
(Internet Engineering Task Force). <cite>RFC 2732: Format for Literal
|
||
IPv6 Addresses in URL's</cite>. R. Hinden, B. Carpenter, L. Masinter.
|
||
1999. (See <a href="http://www.ietf.org/rfc/rfc2732.txt">http://www.ietf.org/rfc/rfc2732.txt</a>.)</div></dd>
|
||
<dt class="label"><span class="diff-add"><a name="rfc2781"></a>IETF RFC 2781</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E77">[E77]</a>
|
||
IETF (Internet Engineering Task Force). <em>RFC 2781: UTF-16, an encoding
|
||
of ISO 10646</em>, ed. P. Hoffman, F. Yergeau. 2000. (See <a href="http://www.ietf.org/rfc/rfc2781.txt">http://www.ietf.org/rfc/rfc2781.txt</a>.)</div></dd>
|
||
<dt class="label"><span class="diff-add"><a name="ISO639"></a>ISO 639</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E38">[E38]</a>
|
||
(International Organization for Standardization). <cite>ISO 639:1988 (E).
|
||
Code for the representation of names of languages.</cite> [Geneva]: International
|
||
Organization for Standardization, 1988.</div></dd>
|
||
<dt class="label"><span class="diff-add"><a name="ISO3166"></a>ISO 3166</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E38">[E38]</a>
|
||
(International Organization for Standardization). <cite>ISO 3166-1:1997
|
||
(E). Codes for the representation of names of countries and their subdivisions --
|
||
Part 1: Country codes</cite> [Geneva]: International Organization for
|
||
Standardization, 1997.</div></dd>
|
||
<dt class="label"><a name="ISO8879"></a>ISO 8879</dt><dd>ISO (International Organization for Standardization). <cite>ISO
|
||
8879:1986(E). Information processing -- Text and Office Systems --
|
||
Standard Generalized Markup Language (SGML).</cite> First edition --
|
||
1986-10-15. [Geneva]: International Organization for Standardization, 1986. </dd>
|
||
<dt class="label"><a name="ISO10744"></a>ISO/IEC 10744</dt><dd>ISO (International Organization for
|
||
Standardization). <cite>ISO/IEC 10744-1992 (E). Information technology --
|
||
Hypermedia/Time-based Structuring Language (HyTime). </cite> [Geneva]:
|
||
International Organization for Standardization, 1992. <em>Extended Facilities
|
||
Annexe.</em> [Geneva]: International Organization for Standardization, 1996. </dd>
|
||
<dt class="label"><span class="diff-add"><a name="websgml"></a>WEBSGML</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E43">[E43]</a>ISO
|
||
(International Organization for Standardization). <cite>ISO 8879:1986
|
||
TC2. Information technology -- Document Description and Processing Languages. </cite>
|
||
[Geneva]: International Organization for Standardization, 1998. (See <a href="http://www.sgmlsource.com/8879rev/n0029.htm">http://www.sgmlsource.com/8879rev/n0029.htm</a>.)</div></dd>
|
||
<dt class="label"><span class="diff-add"><a name="xml-names"></a>XML Names</span></dt><dd><div class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E98">[E98]</a>Tim Bray,
|
||
Dave Hollander, and Andrew Layman, editors. <cite>Namespaces in XML</cite>.
|
||
Textuality, Hewlett-Packard, and Microsoft. World Wide Web Consortium, 1999. (See <a href="http://www.w3.org/TR/REC-xml-names/">http://www.w3.org/TR/REC-xml-names/</a>.)</div></dd>
|
||
</dl></div>
|
||
</div>
|
||
<div class="div1">
|
||
|
||
<h2><a name="CharClasses"></a>B Character Classes</h2>
|
||
<p>Following the characteristics defined in the Unicode standard, characters
|
||
are classed as base characters (among others, these contain the alphabetic
|
||
characters of the Latin alphabet<span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E84">[E84]</a>, without
|
||
diacritics</span>), ideographic characters, and combining characters (among
|
||
others, this class contains most diacritics)<span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E30">[E30]</a>; these classes
|
||
combine to form the class of letters.</span> Digits and extenders are also
|
||
distinguished.</p>
|
||
|
||
<h5>Characters</h5><table class="scrap" summary="Scrap"><tbody>
|
||
<tr valign="baseline"><td><a name="NT-Letter"></a>[84]<5D><><EFBFBD></td><td><code>Letter</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code><a href="#NT-BaseChar">BaseChar</a> | <a href="#NT-Ideographic">Ideographic</a></code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-BaseChar"></a>[85]<5D><><EFBFBD></td><td><code>BaseChar</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>[#x0041-#x005A] |<7C>[#x0061-#x007A] |<7C>[#x00C0-#x00D6]
|
||
|<7C>[#x00D8-#x00F6] |<7C>[#x00F8-#x00FF] |<7C>[#x0100-#x0131] |<7C>[#x0134-#x013E]
|
||
|<7C>[#x0141-#x0148] |<7C>[#x014A-#x017E] |<7C>[#x0180-#x01C3] |<7C>[#x01CD-#x01F0]
|
||
|<7C>[#x01F4-#x01F5] |<7C>[#x01FA-#x0217] |<7C>[#x0250-#x02A8] |<7C>[#x02BB-#x02C1]
|
||
|<7C>#x0386 |<7C>[#x0388-#x038A] |<7C>#x038C |<7C>[#x038E-#x03A1]
|
||
|<7C>[#x03A3-#x03CE] |<7C>[#x03D0-#x03D6] |<7C>#x03DA |<7C>#x03DC
|
||
|<7C>#x03DE |<7C>#x03E0 |<7C>[#x03E2-#x03F3] |<7C>[#x0401-#x040C]
|
||
|<7C>[#x040E-#x044F] |<7C>[#x0451-#x045C] |<7C>[#x045E-#x0481] |<7C>[#x0490-#x04C4]
|
||
|<7C>[#x04C7-#x04C8] |<7C>[#x04CB-#x04CC] |<7C>[#x04D0-#x04EB] |<7C>[#x04EE-#x04F5]
|
||
|<7C>[#x04F8-#x04F9] |<7C>[#x0531-#x0556] |<7C>#x0559 |<7C>[#x0561-#x0586]
|
||
|<7C>[#x05D0-#x05EA] |<7C>[#x05F0-#x05F2] |<7C>[#x0621-#x063A] |<7C>[#x0641-#x064A]
|
||
|<7C>[#x0671-#x06B7] |<7C>[#x06BA-#x06BE] |<7C>[#x06C0-#x06CE] |<7C>[#x06D0-#x06D3]
|
||
|<7C>#x06D5 |<7C>[#x06E5-#x06E6] |<7C>[#x0905-#x0939] |<7C>#x093D
|
||
|<7C>[#x0958-#x0961] |<7C>[#x0985-#x098C] |<7C>[#x098F-#x0990] |<7C>[#x0993-#x09A8]
|
||
|<7C>[#x09AA-#x09B0] |<7C>#x09B2 |<7C>[#x09B6-#x09B9] |<7C>[#x09DC-#x09DD]
|
||
|<7C>[#x09DF-#x09E1] |<7C>[#x09F0-#x09F1] |<7C>[#x0A05-#x0A0A] |<7C>[#x0A0F-#x0A10]
|
||
|<7C>[#x0A13-#x0A28] |<7C>[#x0A2A-#x0A30] |<7C>[#x0A32-#x0A33] |<7C>[#x0A35-#x0A36]
|
||
|<7C>[#x0A38-#x0A39] |<7C>[#x0A59-#x0A5C] |<7C>#x0A5E |<7C>[#x0A72-#x0A74]
|
||
|<7C>[#x0A85-#x0A8B] |<7C>#x0A8D |<7C>[#x0A8F-#x0A91] |<7C>[#x0A93-#x0AA8]
|
||
|<7C>[#x0AAA-#x0AB0] |<7C>[#x0AB2-#x0AB3] |<7C>[#x0AB5-#x0AB9] |<7C>#x0ABD
|
||
|<7C>#x0AE0 |<7C>[#x0B05-#x0B0C] |<7C>[#x0B0F-#x0B10] |<7C>[#x0B13-#x0B28]
|
||
|<7C>[#x0B2A-#x0B30] |<7C>[#x0B32-#x0B33] |<7C>[#x0B36-#x0B39] |<7C>#x0B3D
|
||
|<7C>[#x0B5C-#x0B5D] |<7C>[#x0B5F-#x0B61] |<7C>[#x0B85-#x0B8A] |<7C>[#x0B8E-#x0B90]
|
||
|<7C>[#x0B92-#x0B95] |<7C>[#x0B99-#x0B9A] |<7C>#x0B9C |<7C>[#x0B9E-#x0B9F]
|
||
|<7C>[#x0BA3-#x0BA4] |<7C>[#x0BA8-#x0BAA] |<7C>[#x0BAE-#x0BB5] |<7C>[#x0BB7-#x0BB9]
|
||
|<7C>[#x0C05-#x0C0C] |<7C>[#x0C0E-#x0C10] |<7C>[#x0C12-#x0C28] |<7C>[#x0C2A-#x0C33]
|
||
|<7C>[#x0C35-#x0C39] |<7C>[#x0C60-#x0C61] |<7C>[#x0C85-#x0C8C] |<7C>[#x0C8E-#x0C90]
|
||
|<7C>[#x0C92-#x0CA8] |<7C>[#x0CAA-#x0CB3] |<7C>[#x0CB5-#x0CB9] |<7C>#x0CDE
|
||
|<7C>[#x0CE0-#x0CE1] |<7C>[#x0D05-#x0D0C] |<7C>[#x0D0E-#x0D10] |<7C>[#x0D12-#x0D28]
|
||
|<7C>[#x0D2A-#x0D39] |<7C>[#x0D60-#x0D61] |<7C>[#x0E01-#x0E2E] |<7C>#x0E30
|
||
|<7C>[#x0E32-#x0E33] |<7C>[#x0E40-#x0E45] |<7C>[#x0E81-#x0E82] |<7C>#x0E84
|
||
|<7C>[#x0E87-#x0E88] |<7C>#x0E8A |<7C>#x0E8D |<7C>[#x0E94-#x0E97]
|
||
|<7C>[#x0E99-#x0E9F] |<7C>[#x0EA1-#x0EA3] |<7C>#x0EA5 |<7C>#x0EA7
|
||
|<7C>[#x0EAA-#x0EAB] |<7C>[#x0EAD-#x0EAE] |<7C>#x0EB0 |<7C>[#x0EB2-#x0EB3]
|
||
|<7C>#x0EBD |<7C>[#x0EC0-#x0EC4] |<7C>[#x0F40-#x0F47] |<7C>[#x0F49-#x0F69]
|
||
|<7C>[#x10A0-#x10C5] |<7C>[#x10D0-#x10F6] |<7C>#x1100 |<7C>[#x1102-#x1103]
|
||
|<7C>[#x1105-#x1107] |<7C>#x1109 |<7C>[#x110B-#x110C] |<7C>[#x110E-#x1112]
|
||
|<7C>#x113C |<7C>#x113E |<7C>#x1140 |<7C>#x114C |<7C>#x114E |<7C>#x1150
|
||
|<7C>[#x1154-#x1155] |<7C>#x1159 |<7C>[#x115F-#x1161] |<7C>#x1163
|
||
|<7C>#x1165 |<7C>#x1167 |<7C>#x1169 |<7C>[#x116D-#x116E] |<7C>[#x1172-#x1173]
|
||
|<7C>#x1175 |<7C>#x119E |<7C>#x11A8 |<7C>#x11AB |<7C>[#x11AE-#x11AF]
|
||
|<7C>[#x11B7-#x11B8] |<7C>#x11BA |<7C>[#x11BC-#x11C2] |<7C>#x11EB
|
||
|<7C>#x11F0 |<7C>#x11F9 |<7C>[#x1E00-#x1E9B] |<7C>[#x1EA0-#x1EF9]
|
||
|<7C>[#x1F00-#x1F15] |<7C>[#x1F18-#x1F1D] |<7C>[#x1F20-#x1F45] |<7C>[#x1F48-#x1F4D]
|
||
|<7C>[#x1F50-#x1F57] |<7C>#x1F59 |<7C>#x1F5B |<7C>#x1F5D |<7C>[#x1F5F-#x1F7D]
|
||
|<7C>[#x1F80-#x1FB4] |<7C>[#x1FB6-#x1FBC] |<7C>#x1FBE |<7C>[#x1FC2-#x1FC4]
|
||
|<7C>[#x1FC6-#x1FCC] |<7C>[#x1FD0-#x1FD3] |<7C>[#x1FD6-#x1FDB] |<7C>[#x1FE0-#x1FEC]
|
||
|<7C>[#x1FF2-#x1FF4] |<7C>[#x1FF6-#x1FFC] |<7C>#x2126 |<7C>[#x212A-#x212B]
|
||
|<7C>#x212E |<7C>[#x2180-#x2182] |<7C>[#x3041-#x3094] |<7C>[#x30A1-#x30FA]
|
||
|<7C>[#x3105-#x312C] |<7C>[#xAC00-#xD7A3] </code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-Ideographic"></a>[86]<5D><><EFBFBD></td><td><code>Ideographic</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>[#x4E00-#x9FA5] |<7C>#x3007 |<7C>[#x3021-#x3029] </code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-CombiningChar"></a>[87]<5D><><EFBFBD></td><td><code>CombiningChar</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>[#x0300-#x0345] |<7C>[#x0360-#x0361] |<7C>[#x0483-#x0486]
|
||
|<7C>[#x0591-#x05A1] |<7C>[#x05A3-#x05B9] |<7C>[#x05BB-#x05BD] |<7C>#x05BF
|
||
|<7C>[#x05C1-#x05C2] |<7C>#x05C4 |<7C>[#x064B-#x0652] |<7C>#x0670
|
||
|<7C>[#x06D6-#x06DC] |<7C>[#x06DD-#x06DF] |<7C>[#x06E0-#x06E4] |<7C>[#x06E7-#x06E8]
|
||
|<7C>[#x06EA-#x06ED] |<7C>[#x0901-#x0903] |<7C>#x093C |<7C>[#x093E-#x094C]
|
||
|<7C>#x094D |<7C>[#x0951-#x0954] |<7C>[#x0962-#x0963] |<7C>[#x0981-#x0983]
|
||
|<7C>#x09BC |<7C>#x09BE |<7C>#x09BF |<7C>[#x09C0-#x09C4] |<7C>[#x09C7-#x09C8]
|
||
|<7C>[#x09CB-#x09CD] |<7C>#x09D7 |<7C>[#x09E2-#x09E3] |<7C>#x0A02
|
||
|<7C>#x0A3C |<7C>#x0A3E |<7C>#x0A3F |<7C>[#x0A40-#x0A42] |<7C>[#x0A47-#x0A48]
|
||
|<7C>[#x0A4B-#x0A4D] |<7C>[#x0A70-#x0A71] |<7C>[#x0A81-#x0A83] |<7C>#x0ABC
|
||
|<7C>[#x0ABE-#x0AC5] |<7C>[#x0AC7-#x0AC9] |<7C>[#x0ACB-#x0ACD] |<7C>[#x0B01-#x0B03]
|
||
|<7C>#x0B3C |<7C>[#x0B3E-#x0B43] |<7C>[#x0B47-#x0B48] |<7C>[#x0B4B-#x0B4D]
|
||
|<7C>[#x0B56-#x0B57] |<7C>[#x0B82-#x0B83] |<7C>[#x0BBE-#x0BC2] |<7C>[#x0BC6-#x0BC8]
|
||
|<7C>[#x0BCA-#x0BCD] |<7C>#x0BD7 |<7C>[#x0C01-#x0C03] |<7C>[#x0C3E-#x0C44]
|
||
|<7C>[#x0C46-#x0C48] |<7C>[#x0C4A-#x0C4D] |<7C>[#x0C55-#x0C56] |<7C>[#x0C82-#x0C83]
|
||
|<7C>[#x0CBE-#x0CC4] |<7C>[#x0CC6-#x0CC8] |<7C>[#x0CCA-#x0CCD] |<7C>[#x0CD5-#x0CD6]
|
||
|<7C>[#x0D02-#x0D03] |<7C>[#x0D3E-#x0D43] |<7C>[#x0D46-#x0D48] |<7C>[#x0D4A-#x0D4D]
|
||
|<7C>#x0D57 |<7C>#x0E31 |<7C>[#x0E34-#x0E3A] |<7C>[#x0E47-#x0E4E]
|
||
|<7C>#x0EB1 |<7C>[#x0EB4-#x0EB9] |<7C>[#x0EBB-#x0EBC] |<7C>[#x0EC8-#x0ECD]
|
||
|<7C>[#x0F18-#x0F19] |<7C>#x0F35 |<7C>#x0F37 |<7C>#x0F39 |<7C>#x0F3E
|
||
|<7C>#x0F3F |<7C>[#x0F71-#x0F84] |<7C>[#x0F86-#x0F8B] |<7C>[#x0F90-#x0F95]
|
||
|<7C>#x0F97 |<7C>[#x0F99-#x0FAD] |<7C>[#x0FB1-#x0FB7] |<7C>#x0FB9
|
||
|<7C>[#x20D0-#x20DC] |<7C>#x20E1 |<7C>[#x302A-#x302F] |<7C>#x3099
|
||
|<7C>#x309A </code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-Digit"></a>[88]<5D><><EFBFBD></td><td><code>Digit</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>[#x0030-#x0039] |<7C>[#x0660-#x0669] |<7C>[#x06F0-#x06F9]
|
||
|<7C>[#x0966-#x096F] |<7C>[#x09E6-#x09EF] |<7C>[#x0A66-#x0A6F] |<7C>[#x0AE6-#x0AEF]
|
||
|<7C>[#x0B66-#x0B6F] |<7C>[#x0BE7-#x0BEF] |<7C>[#x0C66-#x0C6F] |<7C>[#x0CE6-#x0CEF]
|
||
|<7C>[#x0D66-#x0D6F] |<7C>[#x0E50-#x0E59] |<7C>[#x0ED0-#x0ED9] |<7C>[#x0F20-#x0F29] </code></td><xsltdebug></xsltdebug></tr>
|
||
<tr valign="baseline"><td><a name="NT-Extender"></a>[89]<5D><><EFBFBD></td><td><code>Extender</code></td><td><EFBFBD><EFBFBD><EFBFBD>::=<3D><><EFBFBD></td><td><code>#x00B7 |<7C>#x02D0 |<7C>#x02D1 |<7C>#x0387 |<7C>#x0640
|
||
|<7C>#x0E46 |<7C>#x0EC6 |<7C>#x3005 |<7C>[#x3031-#x3035] |<7C>[#x309D-#x309E]
|
||
|<7C>[#x30FC-#x30FE] </code></td><xsltdebug></xsltdebug></tr>
|
||
</tbody></table>
|
||
<p>The character classes defined here can be derived from the Unicode <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</a>2.0</span>
|
||
character database as follows:</p>
|
||
<ul>
|
||
<li><p>Name start characters must have one of the categories Ll, Lu, Lo,
|
||
Lt, Nl.</p></li>
|
||
<li><p>Name characters other than Name-start characters must have one of
|
||
the categories Mc, Me, Mn, Lm, or Nd.</p></li>
|
||
<li><p>Characters in the compatibility area (i.e. with character code greater
|
||
than #xF900 and less than #xFFFE) are not allowed in XML names.</p></li>
|
||
<li><p>Characters which have a font or compatibility decomposition (i.e.
|
||
those with a "compatibility formatting tag" in field 5 of the
|
||
database -- marked by field 5 beginning with a "<") are not
|
||
allowed.</p></li>
|
||
<li><p>The following characters are treated as name-start characters rather
|
||
than name characters, because the property file classifies them as Alphabetic:
|
||
[#x02BB-#x02C1], #x0559, #x06E5, #x06E6.</p></li>
|
||
<li><p>Characters #x20DD-#x20E0 are excluded (in accordance with Unicode <span class="diff-add"><a href="http://www.w3.org/XML/xml-19980210-errata#E67">[E67]</a>2.0</span>,
|
||
section 5.14).</p></li>
|
||
<li><p>Character #x00B7 is classified as an extender, because the property
|
||
list so identifies it.</p></li>
|
||
<li><p>Character #x0387 is added as a name character, because #x00B7 is
|
||
its canonical equivalent.</p></li>
|
||
<li><p>Characters ':' and '_' are allowed as name-start characters.</p>
|
||
</li>
|
||
<li><p>Characters '-' and '.' are allowed as name characters.</p></li>
|
||
</ul>
|
||
</div>
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-xml-and-sgml"></a>C XML and SGML (Non-Normative)</h2>
|
||
<p><span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E43">[E43]</a>XML
|
||
is designed to be a subset of SGML, in that every XML document should also
|
||
be a conforming SGML document.</span> For a detailed comparison of the additional
|
||
restrictions that XML places on documents beyond those of SGML, see <a href="#Clark">[Clark]</a>.</p>
|
||
</div>
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-entexpand"></a>D Expansion of Entity and Character References (Non-Normative)</h2>
|
||
<p>This appendix contains some examples illustrating the sequence of entity-
|
||
and character-reference recognition and expansion, as specified in <a href="#entproc"><b>4.4 XML Processor Treatment of Entities and References</b></a>.</p>
|
||
<p>If the DTD contains the declaration</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><!ENTITY example "<p>An ampersand (&#38;#38;) may be escaped
|
||
numerically (&#38;#38;#38;) or with a general entity
|
||
(&amp;amp;).</p>" ></pre></td></tr></table>
|
||
<p>then the XML processor will recognize the character references when it
|
||
parses the entity declaration, and resolve them before storing the following
|
||
string as the value of the entity "<code>example</code>":</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre><p>An ampersand (&#38;) may be escaped
|
||
numerically (&#38;#38;) or with a general entity
|
||
(&amp;amp;).</p></pre></td></tr></table>
|
||
<p>A reference in the document to "<code>&example;</code>"
|
||
will cause the text to be reparsed, at which time the start- and end-tags
|
||
of the <code>p</code> element will be recognized and the three references will
|
||
be recognized and expanded, resulting in a <code>p</code> element with the following
|
||
content (all data, no delimiters or markup):</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre>An ampersand (&) may be escaped
|
||
numerically (&#38;) or with a general entity
|
||
(&amp;).</pre></td></tr></table>
|
||
<p>A more complex example will illustrate the rules and their effects fully.
|
||
In the following example, the line numbers are solely for reference.</p>
|
||
<table class="eg" cellpadding="5" border="1" bgcolor="#99ffff" width="100%" summary="Example"><tr><td><pre>1 <?xml version='1.0'?>
|
||
2 <!DOCTYPE test [
|
||
3 <!ELEMENT test (#PCDATA) >
|
||
4 <!ENTITY % xx '&#37;zz;'>
|
||
5 <!ENTITY % zz '&#60;!ENTITY tricky "error-prone" >' >
|
||
6 %xx;
|
||
7 ]>
|
||
8 <test>This sample shows a &tricky; method.</test></pre></td></tr></table>
|
||
<p>This produces the following:</p>
|
||
<ul>
|
||
<li><p>in line 4, the reference to character 37 is expanded immediately,
|
||
and the parameter entity "<code>xx</code>" is stored in the symbol
|
||
table with the value "<code>%zz;</code>". Since the replacement
|
||
text is not rescanned, the reference to parameter entity "<code>zz</code>"
|
||
is not recognized. (And it would be an error if it were, since "<code>zz</code>"
|
||
is not yet declared.)</p></li>
|
||
<li><p>in line 5, the character reference "<code>&#60;</code>"
|
||
is expanded immediately and the parameter entity "<code>zz</code>"
|
||
is stored with the replacement text "<code><!ENTITY tricky "error-prone"
|
||
></code>", which is a well-formed entity declaration.</p></li>
|
||
<li><p>in line 6, the reference to "<code>xx</code>" is recognized,
|
||
and the replacement text of "<code>xx</code>" (namely "<code>%zz;</code>")
|
||
is parsed. The reference to "<code>zz</code>" is recognized in
|
||
its turn, and its replacement text ("<code><!ENTITY tricky "error-prone"
|
||
></code>") is parsed. The general entity "<code>tricky</code>"
|
||
has now been declared, with the replacement text "<code>error-prone</code>".</p>
|
||
</li>
|
||
<li><p>in line 8, the reference to the general entity "<code>tricky</code>"
|
||
is recognized, and it is expanded, so the full content of the <code>test</code>
|
||
element is the self-describing (and ungrammatical) string <em>This sample
|
||
shows a error-prone method.</em></p></li>
|
||
</ul>
|
||
</div>
|
||
<div class="div1">
|
||
|
||
<h2><a name="determinism"></a>E Deterministic Content Models (Non-Normative)</h2>
|
||
<p><span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E102">[E102]</a>As
|
||
noted in <a href="#sec-element-content"><b>3.2.1 Element Content</b></a>, it is required that content
|
||
models in element type declarations be deterministic. This requirement is <a title="For Compatibility" href="#dt-compat">for compatibility</a> with SGML (which calls deterministic
|
||
content models "unambiguous");</span> XML processors built
|
||
using SGML systems may flag non-deterministic content models as errors.</p>
|
||
<p>For example, the content model <code>((b, c) | (b, d))</code> is non-deterministic,
|
||
because given an initial <code>b</code> the <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E95">[E95]</a>XML processor</span>
|
||
cannot know which <code>b</code> in the model is being matched without looking
|
||
ahead to see which element follows the <code>b</code>. In this case, the two references
|
||
to <code>b</code> can be collapsed into a single reference, making the model read <code>(b,
|
||
(c | d))</code>. An initial <code>b</code> now clearly matches only a single name
|
||
in the content model. The <span class="diff-chg"><a href="http://www.w3.org/XML/xml-19980210-errata#E95">[E95]</a>processor</span> doesn't need to look ahead to see what follows; either <code>c</code> or <code>d</code>
|
||
would be accepted.</p>
|
||
<p>More formally: a finite state automaton may be constructed from the content
|
||
model using the standard algorithms, e.g. algorithm 3.5 in section 3.9 of
|
||
Aho, Sethi, and Ullman <a href="#Aho">[Aho/Ullman]</a>. In many such algorithms, a follow
|
||
set is constructed for each position in the regular expression (i.e., each
|
||
leaf node in the syntax tree for the regular expression); if any position
|
||
has a follow set in which more than one following position is labeled with
|
||
the same element type name, then the content model is in error and may be
|
||
reported as an error.</p>
|
||
<p>Algorithms exist which allow many but not all non-deterministic content
|
||
models to be reduced automatically to equivalent deterministic models; see
|
||
Br<EFBFBD>ggemann-Klein 1991 <a href="#ABK">[Br<42>ggemann-Klein]</a>.</p>
|
||
</div>
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-guessing"></a>F <a href="http://www.w3.org/XML/xml-19980210-errata#E105">[E105]</a><a href="http://www.w3.org/XML/xml-19980210-errata#E48">[E48]</a>Autodetection
|
||
of Character Encodings (Non-Normative)</h2>
|
||
<p>The XML encoding declaration functions as an internal label on each entity,
|
||
indicating which character encoding is in use. Before an XML processor can
|
||
read the internal label, however, it apparently has to know what character
|
||
encoding is in use--which is what the internal label is trying to indicate.
|
||
In the general case, this is a hopeless situation. It is not entirely hopeless
|
||
in XML, however, because XML limits the general case in two ways: each implementation
|
||
is assumed to support only a finite set of character encodings, and the XML
|
||
encoding declaration is restricted in position and content in order to make
|
||
it feasible to autodetect the character encoding in use in each entity in
|
||
normal cases. Also, in many cases other sources of information are available
|
||
in addition to the XML data stream itself. Two cases may be distinguished,
|
||
depending on whether the XML entity is presented to the processor without,
|
||
or with, any accompanying (external) information. We consider the first case
|
||
first.</p>
|
||
<div class="div2">
|
||
<div class="diff-add">
|
||
<h3><a name="sec-guessing-no-ext-info"></a>F.1 Detection Without External Encoding Information</h3></div>
|
||
<p>Because each XML entity <span class="diff-add">not accompanied by external
|
||
encoding information and </span>not in UTF-8 or UTF-16 <span class="diff-chg">encoding</span> <em>must</em>
|
||
begin with an XML encoding declaration, in which the first characters must
|
||
be '<code><?xml</code>', any conforming processor can detect, after two
|
||
to four octets of input, which of the following cases apply. In reading this
|
||
list, it may help to know that in UCS-4, '<' is "<code>#x0000003C</code>"
|
||
and '?' is "<code>#x0000003F</code>", and the Byte Order Mark
|
||
required of UTF-16 data streams is "<code>#xFEFF</code>". <span class="diff-add">The notation <var>##</var> is used to denote any byte value except <span class="diff-chg">that two consecutive <var>##</var>s cannot be both 00</span>.</span></p>
|
||
<div class="diff-add"><p>With a Byte Order Mark:</p></div>
|
||
<div class="diff-add"><table border="1" frame="border"><tbody><tr><td rowspan="1" colspan="1"><code>00 00 FE
|
||
FF</code></td><td rowspan="1" colspan="1">UCS-4, big-endian machine (1234 order)</td></tr><tr><td rowspan="1" colspan="1"><code>FF
|
||
FE 00 00</code></td><td rowspan="1" colspan="1">UCS-4, little-endian machine (4321 order)</td></tr>
|
||
<tr><td rowspan="1" colspan="1"><code>00 00 FF FE</code></td><td rowspan="1" colspan="1">UCS-4, unusual octet order (2143)</td>
|
||
</tr><tr><td rowspan="1" colspan="1"><code>FE FF 00 00</code></td><td rowspan="1" colspan="1">UCS-4, unusual octet order (3412)</td>
|
||
</tr><tr><td rowspan="1" colspan="1"><code>FE FF ## ##</code></td><td rowspan="1" colspan="1">UTF-16, big-endian</td></tr>
|
||
<tr><td rowspan="1" colspan="1"><code>FF FE ## ##</code></td><td rowspan="1" colspan="1">UTF-16, little-endian</td></tr><tr>
|
||
<td rowspan="1" colspan="1"><code>EF BB BF</code></td><td rowspan="1" colspan="1">UTF-8</td></tr></tbody></table></div>
|
||
<div class="diff-add"><p>Without a Byte Order Mark:</p></div>
|
||
<div class="diff-add"><table border="1" frame="border"><tbody><tr><td rowspan="1" colspan="1"><code>00<EFBFBD>00<EFBFBD>00<EFBFBD>3C</code></td>
|
||
<td rowspan="4" colspan="1">UCS-4 or other encoding with a 32-bit code unit and ASCII
|
||
characters encoded as ASCII values, in respectively big-endian (1234), little-endian
|
||
(4321) and two unusual byte orders (2143 and 3412). The encoding declaration
|
||
must be read to determine which of UCS-4 or other supported 32-bit encodings
|
||
applies.</td></tr><tr><td rowspan="1" colspan="1"><code>3C 00 00 00</code></td>
|
||
|
||
</tr><tr><td rowspan="1" colspan="1"><code>00 00 3C 00</code></td>
|
||
|
||
</tr><tr><td rowspan="1" colspan="1"><code>00 3C 00 00</code></td>
|
||
|
||
</tr><tr><td rowspan="1" colspan="1"><code>00 3C 00 3F</code></td><td rowspan="1" colspan="1">UTF-16BE or big-endian ISO-10646-UCS-2
|
||
or other encoding with a 16-bit code unit in big-endian order and ASCII characters
|
||
encoded as ASCII values (the encoding declaration must be read to determine
|
||
which)</td></tr><tr><td rowspan="1" colspan="1"><code>3C 00 3F 00</code></td><td rowspan="1" colspan="1">UTF-16LE or little-endian
|
||
ISO-10646-UCS-2 or other encoding with a 16-bit code unit in little-endian
|
||
order and ASCII characters encoded as ASCII values (the encoding declaration
|
||
must be read to determine which)</td></tr><tr><td rowspan="1" colspan="1"><code>3C 3F 78 6D</code></td>
|
||
<td rowspan="1" colspan="1">UTF-8, ISO 646, ASCII, some part of ISO 8859, Shift-JIS, EUC, or any other
|
||
7-bit, 8-bit, or mixed-width encoding which ensures that the characters of
|
||
ASCII have their normal positions, width, and values; the actual encoding
|
||
declaration must be read to detect which of these applies, but since all of
|
||
these encodings use the same bit patterns for the relevant ASCII characters,
|
||
the encoding declaration itself may be read reliably</td></tr><tr><td rowspan="1" colspan="1"><code>4C
|
||
6F A7 94</code></td><td rowspan="1" colspan="1">EBCDIC (in some flavor; the full encoding declaration
|
||
must be read to tell which code page is in use)</td></tr><tr><td rowspan="1" colspan="1">Other</td>
|
||
<td rowspan="1" colspan="1">UTF-8 without an encoding declaration, or else the data stream is mislabeled
|
||
(lacking a required encoding declaration), corrupt, fragmentary, or enclosed
|
||
in a wrapper of some kind</td></tr></tbody></table></div>
|
||
<div class="diff-add"><div class="note"><p class="prefix"><b>Note:</b></p>
|
||
<p>In cases above which do not require reading the encoding declaration to
|
||
determine the encoding, section 4.3.3 still requires that the encoding declaration,
|
||
if present, be read and that the encoding name be checked to match the actual
|
||
encoding of the entity. Also, it is possible that new character encodings
|
||
will be invented that will make it necessary to use the encoding declaration
|
||
to determine the encoding, in cases where this is not required at present.</p>
|
||
</div></div>
|
||
<p>This level of autodetection is enough to read the XML encoding declaration
|
||
and parse the character-encoding identifier, which is still necessary to distinguish
|
||
the individual members of each family of encodings (e.g. to tell UTF-8 from
|
||
8859, and the parts of 8859 from each other, or to distinguish the specific
|
||
EBCDIC code page in use, and so on).</p>
|
||
<p>Because the contents of the encoding declaration are restricted to <span class="diff-chg">characters from the ASCII repertoire (however encoded)</span>,
|
||
a processor can reliably read the entire encoding declaration as soon as it
|
||
has detected which family of encodings is in use. Since in practice, all widely
|
||
used character encodings fall into one of the categories above, the XML encoding
|
||
declaration allows reasonably reliable in-band labeling of character encodings,
|
||
even when external sources of information at the operating-system or transport-protocol
|
||
level are unreliable. <span class="diff-del">Note that since external parsed entities
|
||
in UTF-16 may begin with any character, this autodetection does not always
|
||
work. Also, </span><span class="diff-add">Character encodings such as UTF-7
|
||
that make overloaded usage of ASCII-valued bytes may fail to be reliably detected.</span></p>
|
||
<p>Once the processor has detected the character encoding in use, it can act
|
||
appropriately, whether by invoking a separate input routine for each case,
|
||
or by calling the proper conversion function on each character of input.</p>
|
||
<p>Like any self-labeling system, the XML encoding declaration will not work
|
||
if any software changes the entity's character set or encoding without updating
|
||
the encoding declaration. Implementors of character-encoding routines should
|
||
be careful to ensure the accuracy of the internal and external information
|
||
used to label the entity.</p>
|
||
</div>
|
||
<div class="div2">
|
||
<div class="diff-add">
|
||
<h3><a name="sec-guessing-with-ext-info"></a>F.2 Priorities in the Presence of External Encoding Information</h3></div>
|
||
<p>The second possible case occurs when the XML entity is accompanied by encoding
|
||
information, as in some file systems and some network protocols. When multiple
|
||
sources of information are available, their relative priority and the preferred
|
||
method of handling conflict should be specified as part of the higher-level
|
||
protocol used to deliver XML. <span class="diff-chg">In particular, please refer
|
||
to <a href="#rfc2376">[IETF RFC 2376]</a> or its successor, which defines the <code>text/xml</code>
|
||
and <code>application/xml</code> MIME types and provides some useful guidance.
|
||
In the interests of interoperability, however, the following rule is recommended.</span></p>
|
||
<ul>
|
||
<li><p>If an XML entity is in a file, the Byte-Order Mark and encoding declaration <span class="diff-del">PI </span>are used (if present) to determine the character encoding.<span class="diff-del"><a href="http://www.w3.org/XML/xml-19980210-errata#E74">[E74]</a>
|
||
All other heuristics and sources of information are solely for error recovery.</span></p>
|
||
</li>
|
||
</ul>
|
||
<div class="diff-del"><ul>
|
||
<li><p>If an XML entity is delivered with a MIME type of text/xml, then
|
||
the <code>charset</code> parameter on the MIME type determines the character
|
||
encoding method; all other heuristics and sources of information are solely
|
||
for error recovery.</p></li>
|
||
<li><p>If an XML entity is delivered with a MIME type of application/xml,
|
||
then the Byte-Order Mark and encoding-declaration PI are used (if present)
|
||
to determine the character encoding. All other heuristics and sources of information
|
||
are solely for error recovery.</p></li>
|
||
</ul></div>
|
||
<div class="diff-del"><p>These rules apply only in the absence of protocol-level documentation;
|
||
in particular, when the MIME types text/xml and application/xml are defined,
|
||
the recommendations of the relevant RFC will supersede these rules.</p></div>
|
||
</div>
|
||
</div>
|
||
<div class="div1">
|
||
|
||
<h2><a name="sec-xml-wg"></a>G W3C XML Working Group (Non-Normative)</h2>
|
||
<p>This specification was prepared and approved for publication by the W3C
|
||
XML Working Group (WG). WG approval of this specification does not necessarily
|
||
imply that all WG members voted for its approval. The current and former members
|
||
of the XML WG are:</p>
|
||
<ul>
|
||
<li>Jon Bosak, Sun (<i>Chair</i>)
|
||
</li>
|
||
<li>James Clark (<i>Technical Lead</i>) </li>
|
||
<li>Tim Bray, Textuality and Netscape
|
||
(<i>XML Co-editor</i>) </li>
|
||
<li>Jean Paoli, Microsoft (<i>XML
|
||
Co-editor</i>) </li>
|
||
<li>C. M. Sperberg-McQueen, U. of Ill.
|
||
(<i>XML Co-editor</i>) </li>
|
||
<li>Dan Connolly, W3C (<i>W3C Liaison</i>)
|
||
</li>
|
||
<li>Paula Angerstein, Texcel</li>
|
||
<li>Steve DeRose, INSO</li>
|
||
<li>Dave Hollander, HP</li>
|
||
<li>Eliot Kimber, ISOGEN</li>
|
||
<li>Eve Maler, ArborText</li>
|
||
<li>Tom Magliery, NCSA</li>
|
||
<li>Murray Maloney<span class="diff-chg">, SoftQuad, Grif
|
||
SA, Muzmo and Veo Systems</span></li>
|
||
<li><span class="diff-chg">MURATA Makoto (FAMILY Given)</span>, Fuji
|
||
Xerox Information Systems</li>
|
||
<li>Joel Nava, Adobe</li>
|
||
<li>Conleth O'Connell, Vignette
|
||
</li>
|
||
<li>Peter Sharpe, SoftQuad</li>
|
||
<li>John Tigue, DataChannel</li>
|
||
</ul>
|
||
</div>
|
||
<div class="diff-add"><div class="div1">
|
||
|
||
<h2><a name="sec-core-wg"></a>H W3C XML Core Group (Non-Normative)</h2>
|
||
<p>The second edition of this specification was prepared by the W3C XML Core
|
||
Working Group (WG). The members of the WG at the time of publication of this
|
||
edition were:</p>
|
||
<ul>
|
||
<li>Paula Angerstein, Vignette</li>
|
||
<li>Daniel Austin, Ask Jeeves</li>
|
||
<li>Tim Boland</li>
|
||
<li>Allen Brown, Microsoft</li>
|
||
<li>Dan Connolly, W3C (<i>Staff
|
||
Contact</i>) </li>
|
||
<li>John Cowan, Reuters Limited
|
||
</li>
|
||
<li>John Evdemon, XMLSolutions Corporation
|
||
</li>
|
||
<li>Paul Grosso, Arbortext (<i>Co-Chair</i>)
|
||
</li>
|
||
<li>Arnaud Le Hors, IBM (<i>Co-Chair</i>)
|
||
</li>
|
||
<li>Eve Maler, Sun Microsystems
|
||
(<i>Second Edition Editor</i>) </li>
|
||
<li>Jonathan Marsh, Microsoft</li>
|
||
<li>MURATA Makoto (FAMILY Given), IBM
|
||
</li>
|
||
<li>Mark Needleman, Data Research Associates
|
||
</li>
|
||
<li>David Orchard, Jamcracker</li>
|
||
<li>Lew Shannon, NCR</li>
|
||
<li>Richard Tobin, University of Edinburgh
|
||
</li>
|
||
<li>Daniel Veillard, W3C</li>
|
||
<li>Dan Vint, Lexica</li>
|
||
<li>Norman Walsh, Sun Microsystems
|
||
</li>
|
||
<li>Fran<EFBFBD>ois Yergeau, Alis Technologies
|
||
(<i>Errata List Editor</i>) </li>
|
||
<li>Kongyi Zhou, Oracle</li>
|
||
</ul>
|
||
</div></div>
|
||
<div class="diff-add"><div class="div1">
|
||
|
||
<h2><a name="id2683713"></a>I Production Notes (Non-Normative)</h2>
|
||
<p>This Second Edition was encoded in the <a href="http://www.w3.org/XML/1998/06/xmlspec-v21.dtd">XMLspec
|
||
DTD</a> (which has <a href="http://www.w3.org/XML/1998/06/xmlspec-report-v21.htm">documentation</a>
|
||
available). The HTML versions were produced with a combination of the <a href="http://www.w3.org/XML/1998/06/xmlspec.xsl">xmlspec.xsl</a>, <a href="http://www.w3.org/XML/1998/06/diffspec.xsl">diffspec.xsl</a>,
|
||
and <a href="http://www.w3.org/XML/1998/06/REC-xml-2e.xsl">REC-xml-2e.xsl</a>
|
||
XSLT stylesheets. The PDF version was produced with the <a href="http://www.tdb.uu.se/~jan/html2ps.html">html2ps</a>
|
||
facility and a distiller program.</p>
|
||
</div></div>
|
||
</div></body></html>
|