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gerrit-public.fairphone.software / platform / external / libxml2 / df4223ece455246e24d76b6617d086cb99ccb609 / . / result / valid / xhtml1.xhtml
blob: 907209bf687cd5079bbfc99c1425c81fc60c5d8a [file] [log] [blame]
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1<?xml version="1.0"?>
2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "dtds/xhtml1-strict.dtd">
3<?xml-stylesheet href="W3C-PR.css" type="text/css"?>
Daniel Veillard6f4561a2002-03-25 12:10:14 +0000[diff] [blame]4<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]5<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]6<title>XHTML 1.0: The Extensible HyperText Markup
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]7Language</title>
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]8<link rel="stylesheet" href="W3C-PR.css" type="text/css" />
Daniel Veillardef8dd7b2003-03-23 12:02:56 +0000[diff] [blame]9<style type="text/css">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]10span.term { font-style: italic; color: rgb(0, 0, 192) }
11code {
12 color: green;
13 font-family: monospace;
14 font-weight: bold;
15}
16
17code.greenmono {
18 color: green;
19 font-family: monospace;
20 font-weight: bold;
21}
22.good {
23 border: solid green;
24 border-width: 2px;
25 color: green;
26 font-weight: bold;
27 margin-right: 5%;
28 margin-left: 0;
29}
30.bad {
31 border: solid red;
32 border-width: 2px;
33 margin-left: 0;
34 margin-right: 5%;
35 color: rgb(192, 101, 101);
36}
37
38img {
39 color: white;
40 border: none;
41}
42
43div.navbar { text-align: center; }
44div.contents {
45 background-color: rgb(204,204,255);
46 padding: 0.5em;
47 border: none;
48 margin-right: 5%;
49}
50.tocline { list-style: none; }
51table.exceptions { background-color: rgb(255,255,153); }
Daniel Veillardef8dd7b2003-03-23 12:02:56 +0000[diff] [blame]52</style>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]53</head>
54<body>
55<div class="navbar">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]56 <a href="#toc">table of contents</a>
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]57 <hr />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]58</div>
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]59<div class="head"><p><a href="http://www.w3.org/"><img class="head" src="w3c_home.gif" alt="W3C" /></a></p>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]60
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]61<h1 class="head"><a name="title" id="title">XHTML</a><sup>&#x2122;</sup> 1.0:
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]62The Extensible HyperText Markup Language</h1>
63
64<h2>A Reformulation of HTML 4.0 in XML 1.0</h2>
65
66<h3>W3C Proposed Recommendation 10 December 1999</h3>
67
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]68<dl>
69<dt>This version:</dt>
70
71<dd><a href="http://www.w3.org/TR/1999/PR-xhtml1-19991210">
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]72http://www.w3.org/TR/1999/PR-xhtml1-19991210</a> <br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]73(<a href="xhtml1.ps">Postscript version</a>,
74<a href="xhtml1.pdf">PDF version</a>,
75<a href="xhtml1.zip">ZIP archive</a>, or
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]76<a href="xhtml1.tgz">Gzip'd TAR archive</a>)
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]77</dd>
78
79<dt>Latest version:</dt>
80
81<dd><a href="http://www.w3.org/TR/xhtml1">
82http://www.w3.org/TR/xhtml1</a></dd>
83
84<dt>Previous versions:</dt>
85
86<dd><a href="http://www.w3.org/TR/1999/WD-xhtml1-19991124">
87http://www.w3.org/TR/1999/WD-xhtml1-19991124</a></dd>
88<dd><a href="http://www.w3.org/TR/1999/PR-xhtml1-19990824">
89http://www.w3.org/TR/1999/PR-xhtml1-19990824</a></dd>
90
91<dt>Authors:</dt>
92
93<dd>See <a href="#acks">acknowledgements</a>.</dd>
94</dl>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]95
96<p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">
97Copyright</a> &copy; 1999 <a href="http://www.w3.org/">W3C</a><sup>&reg;</sup>
98(<a href="http://www.lcs.mit.edu/">MIT</a>, <a href="http://www.inria.fr/">INRIA</a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. <abbr title="World Wide Web Consortium">W3C</abbr> <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">
99liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">
100trademark</a>, <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document
101use</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-software">software
102licensing</a> rules apply.</p>
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]103<hr />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]104</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]105
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]106<h2 class="notoc">Abstract</h2>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]107
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]108<p>This specification defines <abbr title="Extensible Hypertext Markup Language">XHTML</abbr> 1.0, a reformulation of HTML
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1094.0 as an XML 1.0 application, and three <abbr title="Document Type Definition">DTDs</abbr> corresponding to
110the ones defined by HTML 4.0. The semantics of the elements and
111their attributes are defined in the W3C Recommendation for HTML
1124.0. These semantics provide the foundation for future
113extensibility of XHTML. Compatibility with existing HTML user
114agents is possible by following a small set of guidelines.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]115
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]116<h2>Status of this document</h2>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]117
118<p><em>This section describes the status of this document at the time
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]119of its publication. Other documents may supersede this document. The
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]120latest status of this document series is maintained at the W3C.</em></p>
121
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]122<p>This specification is a Proposed Recommendation of the HTML Working Group. It is
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]123a revision of the Proposed Recommendation dated <a href="http://www.w3.org/TR/1999/PR-xhtml1-19990824/">24 August
1241999</a> incorporating changes as a result of comments from the Proposed
125Recommendation review, and
126comments and further deliberations of the W3C HTML Working Group. A
127<a href="xhtml1-diff-19991210.html">diff-marked version</a> from the previous
128proposed recommendation is available for comparison purposes.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]129
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]130<p>On 10 December 1999, this document enters a
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]131<a href="http://www.w3.org/Consortium/Process/#RecsPR">
132Proposed Recommendation</a> review period. From that date until 8 January
1332000,
134W3C Advisory Committee representatives are encouraged
135to review this specification and return comments in their completed
136ballots to w3c-html-review@w3.org. Please send any comments of a
137confidential nature in separate email to w3t-html@w3.org, which is
138visible to the Team only.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]139
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]140<p>No sooner than 14 days after the end of the review period, the
141Director will announce the document's disposition: it may become a W3C
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]142Recommendation (possibly with minor changes), it may revert to Working
143Draft status, or it may be dropped as a W3C work item.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]144
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]145<p>Publication as a Proposed Recommendation does not imply endorsement
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]146by the W3C membership. This is still a draft document and may be
147updated, replaced or obsoleted by other documents at any time. It is
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]148inappropriate to cite W3C Proposed Recommendation as other than "work
149in progress."</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]150
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]151<p>This document has been produced as part of the <a href="http://www.w3.org/MarkUp/">W3C HTML Activity</a>. The goals of
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]152the <a href="http://www.w3.org/MarkUp/Group/">HTML Working
153Group</a> <i>(<a href="http://cgi.w3.org/MemberAccess/">members
154only</a>)</i> are discussed in the <a href="http://www.w3.org/MarkUp/Group/HTMLcharter">HTML Working Group
155charter</a> <i>(<a href="http://cgi.w3.org/MemberAccess/">members
156only</a>)</i>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]157
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]158<p>A list of current W3C Recommendations and other technical documents
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]159can be found at <a href="http://www.w3.org/TR">http://www.w3.org/TR</a>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]160
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]161<p>Public discussion on <abbr title="HyperText Markup Language">HTML</abbr> features takes place on the mailing list <a href="mailto:www-html@w3.org"> www-html@w3.org</a> (<a href="http://lists.w3.org/Archives/Public/www-html/">archive</a>). The W3C
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]162staff contact for work on HTML is <a href="mailto:dsr@w3.org">Dave
163Raggett</a>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]164
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]165<p>Please report errors in this document to <a href="mailto:www-html-editor@w3.org">www-html-editor@w3.org</a>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]166
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]167<p>The list of known errors in this specification is available at <a href="http://www.w3.org/1999/12/PR-xhtml1-19991210-errata">http://www.w3.org/1999/12/PR-xhtml1-19991210-errata</a>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]168
169<h2 class="notoc"><a id="toc" name="toc">Contents</a></h2>
170
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]171<div class="contents">
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]172<ul class="toc">
173<li class="tocline">1. <a href="#xhtml">What is XHTML?</a>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]174
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]175<ul class="toc">
176<li class="tocline">1.1 <a href="#html4">What is HTML 4.0?</a></li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]177
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]178<li class="tocline">1.2 <a href="#xml">What is XML?</a></li>
179
180<li class="tocline">1.3 <a href="#why">Why the need for XHTML?</a></li>
181</ul>
182</li>
183
184<li class="tocline">2. <a href="#defs">Definitions</a>
185
186<ul class="toc">
187<li class="tocline">2.1 <a href="#terms">Terminology</a></li>
188
189<li class="tocline">2.2 <a href="#general">General Terms</a></li>
190</ul>
191</li>
192
193<li class="tocline">3. <a href="#normative">Normative Definition of XHTML 1.0</a>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]194
195
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]196<ul class="toc">
197<li class="tocline">3.1 <a href="#docconf">Document Conformance</a></li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]198
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]199<li class="tocline">3.2 <a href="#uaconf">User Agent Conformance</a></li>
200</ul>
201</li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]202
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]203<li class="tocline">4. <a href="#diffs">Differences with HTML 4.0</a>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]204
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]205</li>
206
207<li class="tocline">5. <a href="#issues">Compatibility Issues</a>
208
209<ul class="toc">
210<li class="tocline">5.1 <a href="#media">Internet Media Types</a></li>
211</ul>
212</li>
213
214<li class="tocline">6. <a href="#future">Future Directions</a>
215
216<ul class="toc">
217<li class="tocline">6.1 <a href="#mods">Modularizing HTML</a></li>
218
219<li class="tocline">6.2 <a href="#extensions">Subsets and Extensibility</a></li>
220
221<li class="tocline">6.3 <a href="#profiles">Document Profiles</a></li>
222</ul>
223</li>
224
225<li class="tocline"><a href="#dtds">Appendix A. DTDs</a></li>
226
227<li class="tocline"><a href="#prohibitions">Appendix B. Element
228Prohibitions</a></li>
229
230<li class="tocline"><a href="#guidelines">Appendix C. HTML Compatibility Guidelines</a></li>
231
232<li class="tocline"><a href="#acks">Appendix D. Acknowledgements</a></li>
233
234<li class="tocline"><a href="#refs">Appendix E. References</a></li>
235</ul>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]236</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]237
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]238<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]239<h1><a name="xhtml" id="xhtml">1. What is XHTML?</a></h1>
240
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]241<p>XHTML is a family of current and future document types and modules that
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]242reproduce, subset, and extend HTML 4.0 <a href="#ref-html4">[HTML]</a>. XHTML family document types are <abbr title="Extensible Markup Language">XML</abbr> based,
243and ultimately are designed to work in conjunction with XML-based user agents.
244The details of this family and its evolution are
245discussed in more detail in the section on <a href="#future">Future
246Directions</a>. </p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]247
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]248<p>XHTML 1.0 (this specification) is the first document type in the XHTML
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]249family. It is a reformulation of the three HTML 4.0 document types as
250applications of XML 1.0 <a href="#ref-xml"> [XML]</a>. It is intended
251to be used as a language for content that is both XML-conforming and, if some
252simple <a href="#guidelines">guidelines</a> are followed,
253operates in HTML 4.0 conforming user agents. Developers who migrate
254their content to XHTML 1.0 will realize the following benefits:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]255
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]256<ul>
257<li>XHTML documents are XML conforming. As such, they are readily viewed,
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]258edited, and validated with standard XML tools.</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]259<li>XHTML documents can be written to
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]260to operate as well or better than they did before in existing
261HTML 4.0-conforming user agents as well as in new, XHTML 1.0 conforming user
262agents.</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]263<li>XHTML documents can utilize applications (e.g. scripts and applets) that rely
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]264upon either the HTML Document Object Model or the XML Document Object Model <a href="#ref-dom">[DOM]</a>.</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]265<li>As the XHTML family evolves, documents conforming to XHTML 1.0 will be more
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]266likely to interoperate within and among various XHTML environments.</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]267</ul>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]268
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]269<p>The XHTML family is the next step in the evolution of the Internet. By
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]270migrating to XHTML today, content developers can enter the XML world with all
271of its attendant benefits, while still remaining confident in their
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]272content's backward and future compatibility.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]273
274<h2><a name="html4" id="html4">1.1 What is HTML 4.0?</a></h2>
275
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]276<p>HTML 4.0 <a href="#ref-html4">[HTML]</a> is an <abbr title="Standard Generalized Markup Language">SGML</abbr> (Standard
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]277Generalized Markup Language) application conforming to
278International Standard <abbr title="Organization for International Standardization">ISO</abbr> 8879, and is widely regarded as the
279standard publishing language of the World Wide Web.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]280
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]281<p>SGML is a language for describing markup languages,
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]282particularly those used in electronic document exchange, document
283management, and document publishing. HTML is an example of a
284language defined in SGML.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]285
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]286<p>SGML has been around since the middle 1980's and has remained
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]287quite stable. Much of this stability stems from the fact that the
288language is both feature-rich and flexible. This flexibility,
289however, comes at a price, and that price is a level of
290complexity that has inhibited its adoption in a diversity of
291environments, including the World Wide Web.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]292
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]293<p>HTML, as originally conceived, was to be a language for the
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]294exchange of scientific and other technical documents, suitable
295for use by non-document specialists. HTML addressed the problem
296of SGML complexity by specifying a small set of structural and
297semantic tags suitable for authoring relatively simple documents.
298In addition to simplifying the document structure, HTML added
299support for hypertext. Multimedia capabilities were added
300later.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]301
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]302<p>In a remarkably short space of time, HTML became wildly
303popular and rapidly outgrew its original purpose. Since HTML's
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]304inception, there has been rapid invention of new elements for use
305within HTML (as a standard) and for adapting HTML to vertical,
306highly specialized, markets. This plethora of new elements has
307led to compatibility problems for documents across different
308platforms.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]309
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]310<p>As the heterogeneity of both software and platforms rapidly
311proliferate, it is clear that the suitability of 'classic' HTML
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]3124.0 for use on these platforms is somewhat limited.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]313
314<h2><a name="xml" id="xml">1.2 What is XML?</a></h2>
315
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]316<p>XML<sup>&#x2122;</sup> is the shorthand for Extensible Markup
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]317Language, and is an acronym of Extensible Markup Language <a href="#ref-xml">[XML]</a>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]318
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]319<p>XML was conceived as a means of regaining the power and
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]320flexibility of SGML without most of its complexity. Although a
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]321restricted form of SGML, XML nonetheless preserves most of SGML's
322power and richness, and yet still retains all of SGML's commonly
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]323used features.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]324
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]325<p>While retaining these beneficial features, XML removes many of
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]326the more complex features of SGML that make the authoring and
327design of suitable software both difficult and costly.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]328
329<h2><a name="why" id="why">1.3 Why the need for XHTML?</a></h2>
330
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]331<p>The benefits of migrating to XHTML 1.0 are described above. Some of the
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]332benefits of migrating to XHTML in general are:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]333
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]334<ul>
335<li>Document developers and user agent designers are constantly
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]336discovering new ways to express their ideas through new markup. In XML, it is
337relatively easy to introduce new elements or additional element
338attributes. The XHTML family is designed to accommodate these extensions
339through XHTML modules and techniques for developing new XHTML-conforming
340modules (described in the forthcoming XHTML Modularization specification).
341These modules will permit the combination of existing and
342new feature sets when developing content and when designing new user
343agents.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]344
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]345<li>Alternate ways of accessing the Internet are constantly being
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]346introduced. Some estimates indicate that by the year 2002, 75% of
347Internet document viewing will be carried out on these alternate
348platforms. The XHTML family is designed with general user agent
349interoperability in mind. Through a new user agent and document profiling
350mechanism, servers, proxies, and user agents will be able to perform
351best effort content transformation. Ultimately, it will be possible to
352develop XHTML-conforming content that is usable by any XHTML-conforming
353user agent.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]354
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]355</ul>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]356<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]357<h1><a name="defs" id="defs">2. Definitions</a></h1>
358
359<h2><a name="terms" id="terms">2.1 Terminology</a></h2>
360
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]361<p>The following terms are used in this specification. These
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]362terms extend the definitions in <a href="#ref-rfc2119">
363[RFC2119]</a> in ways based upon similar definitions in ISO/<abbr title="International Electro-technical Commission">IEC</abbr>
3649945-1:1990 <a href="#ref-posix">[POSIX.1]</a>:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]365
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]366<dl>
367<dt>Implementation-defined</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]368
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]369<dd>A value or behavior is implementation-defined when it is left
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]370to the implementation to define [and document] the corresponding
371requirements for correct document construction.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]372
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]373<dt>May</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]374
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]375<dd>With respect to implementations, the word "may" is to be
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]376interpreted as an optional feature that is not required in this
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]377specification but can be provided. With respect to <a href="#docconf">Document Conformance</a>, the word "may" means that
378the optional feature must not be used. The term "optional" has
379the same definition as "may".</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]380
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]381<dt>Must</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]382
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]383<dd>In this specification, the word "must" is to be interpreted
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]384as a mandatory requirement on the implementation or on Strictly
385Conforming XHTML Documents, depending upon the context. The term
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]386"shall" has the same definition as "must".</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]387
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]388<dt>Reserved</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]389
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]390<dd>A value or behavior is unspecified, but it is not allowed to
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]391be used by Conforming Documents nor to be supported by a
392Conforming User Agents.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]393
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]394<dt>Should</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]395
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]396<dd>With respect to implementations, the word "should" is to be
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]397interpreted as an implementation recommendation, but not a
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]398requirement. With respect to documents, the word "should" is to
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]399be interpreted as recommended programming practice for documents
400and a requirement for Strictly Conforming XHTML Documents.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]401
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]402<dt>Supported</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]403
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]404<dd>Certain facilities in this specification are optional. If a
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]405facility is supported, it behaves as specified by this
406specification.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]407
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]408<dt>Unspecified</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]409
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]410<dd>When a value or behavior is unspecified, the specification
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]411defines no portability requirements for a facility on an
412implementation even when faced with a document that uses the
413facility. A document that requires specific behavior in such an
414instance, rather than tolerating any behavior when using that
415facility, is not a Strictly Conforming XHTML Document.</dd>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]416</dl>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]417
418<h2><a name="general" id="general">2.2 General Terms</a></h2>
419
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]420<dl>
421<dt>Attribute</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]422
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]423<dd>An attribute is a parameter to an element declared in the
424DTD. An attribute's type and value range, including a possible
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]425default value, are defined in the DTD.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]426
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]427<dt>DTD</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]428
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]429<dd>A DTD, or document type definition, is a collection of XML
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]430declarations that, as a collection, defines the legal structure,
431<span class="term">elements</span>, and <span class="term">
432attributes</span> that are available for use in a document that
433complies to the DTD.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]434
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]435<dt>Document</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]436
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]437<dd>A document is a stream of data that, after being combined
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]438with any other streams it references, is structured such that it
439holds information contained within <span class="term">
440elements</span> that are organized as defined in the associated
441<span class="term">DTD</span>. See <a href="#docconf">Document
442Conformance</a> for more information.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]443
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]444<dt>Element</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]445
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]446<dd>An element is a document structuring unit declared in the
447<span class="term">DTD</span>. The element's content model is
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]448defined in the <span class="term">DTD</span>, and additional
449semantics may be defined in the prose description of the
450element.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]451
452<dt><a name="facilities" id="facilities">Facilities</a></dt>
453
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]454<dd>Functionality includes <span class="term">elements</span>,
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]455<span class="term">attributes</span>, and the semantics
456associated with those <span class="term">elements</span> and
457<span class="term">attributes</span>. An implementation
458supporting that functionality is said to provide the necessary
459facilities.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]460
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]461<dt>Implementation</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]462
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]463<dd>An implementation is a system that provides collection of
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]464<span class="term">facilities</span> and services that supports
465this specification. See <a href="#uaconf">User Agent
466Conformance</a> for more information.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]467
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]468<dt>Parsing</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]469
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]470<dd>Parsing is the act whereby a <span class="term">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]471document</span> is scanned, and the information contained within
472the <span class="term">document</span> is filtered into the
473context of the <span class="term">elements</span> in which the
474information is structured.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]475
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]476<dt>Rendering</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]477
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]478<dd>Rendering is the act whereby the information in a <span class="term">document</span> is presented. This presentation is
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]479done in the form most appropriate to the environment (e.g.
480aurally, visually, in print).</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]481
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]482<dt>User Agent</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]483
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]484<dd>A user agent is an <span class="term">implementation</span>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]485that retrieves and processes XHTML documents. See <a href="#uaconf">User Agent Conformance</a> for more information.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]486
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]487<dt>Validation</dt>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]488
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]489<dd>Validation is a process whereby <span class="term">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]490documents</span> are verified against the associated <span class="term">DTD</span>, ensuring that the structure, use of <span class="term">elements</span>, and use of <span class="term">
491attributes</span> are consistent with the definitions in the
492<span class="term">DTD</span>.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]493
494<dt><a name="wellformed" id="wellformed">Well-formed</a></dt>
495
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]496<dd>A <span class="term">document</span> is well-formed when it
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]497is structured according to the rules defined in <a href="http://www.w3.org/TR/REC-xml#sec-well-formed">Section 2.1</a> of
498the XML 1.0 Recommendation <a href="#ref-xml">[XML]</a>.
499Basically, this definition states that elements, delimited by
500their start and end tags, are nested properly within one
501another.</dd>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]502</dl>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]503
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]504<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]505<h1><a name="normative" id="normative">3. Normative Definition of
506XHTML 1.0</a></h1>
507
508<h2><a name="docconf" id="docconf">3.1 Document
509Conformance</a></h2>
510
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]511<p>This version of XHTML provides a definition of strictly
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]512conforming XHTML documents, which are restricted to tags and
513attributes from the XHTML namespace. See <a href="#well-formed">Section 3.1.2</a> for information on using XHTML
514with other namespaces, for instance, to include metadata
515expressed in <abbr title="Resource Description Format">RDF</abbr> within XHTML documents.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]516
517<h3><a name="strict" id="strict">3.1.1 Strictly Conforming
518Documents</a></h3>
519
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]520<p>A Strictly Conforming XHTML Document is a document that
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]521requires only the facilities described as mandatory in this
522specification. Such a document must meet all of the following
523criteria:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]524
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]525<ol>
526<li>
527<p>It must validate against one of the three DTDs found in <a href="#dtds">Appendix&#xA0;A</a>.</p>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]528</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]529
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]530<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]531<p>The root element of the document must be <code>
532&lt;html&gt;</code>.</p>
533</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]534
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]535<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]536<p>The root element of the document must designate the XHTML
537namespace using the <code>xmlns</code> attribute <a href="#ref-xmlns">[XMLNAMES]</a>. The namespace for XHTML is
538defined to be
539<code>http://www.w3.org/1999/xhtml</code>.</p>
540</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]541
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]542<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]543<p>There must be a DOCTYPE declaration in the document prior to
544the root element. The public identifier included in
545the DOCTYPE declaration must reference one of the three DTDs
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]546found in <a href="#dtds">Appendix&#xA0;A</a> using the respective
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]547Formal Public Identifier. The system identifier may be changed to reflect
548local system conventions.</p>
549
550<pre>
551&lt;!DOCTYPE html
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]552 PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
553 "http://www.w3.org/TR/1999/PR-xhtml1-19991210/DTD/xhtml1-strict.dtd&gt;
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]554
555&lt;!DOCTYPE html
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]556 PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
557 "http://www.w3.org/TR/1999/PR-xhtml1-19991210/DTD/xhtml1-transitional.dtd&gt;
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]558
559&lt;!DOCTYPE html
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]560 PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN"
561 "http://www.w3.org/TR/1999/PR-xhtml1-19991210/DTD/xhtml1-frameset.dtd&gt;
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]562</pre>
563</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]564</ol>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]565
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]566<p>Here is an example of a minimal XHTML document.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]567
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]568<div class="good">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]569<pre>
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]570&lt;?xml version="1.0" encoding="UTF-8"?&gt;
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]571&lt;!DOCTYPE html
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]572 PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
573 "http://www.w3.org/TR/1999/PR-xhtml1-19991210/DTD/xhtml1-strict.dtd"&gt;
574&lt;html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"&gt;
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]575 &lt;head&gt;
576 &lt;title&gt;Virtual Library&lt;/title&gt;
577 &lt;/head&gt;
578 &lt;body&gt;
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]579 &lt;p&gt;Moved to &lt;a href="http://vlib.org/"&gt;vlib.org&lt;/a&gt;.&lt;/p&gt;
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]580 &lt;/body&gt;
581&lt;/html&gt;</pre>
582</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]583
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]584<p>Note that in this example, the XML declaration is included. An XML
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]585declaration like the one above is
586not required in all XML documents. XHTML document authors are strongly encouraged to use XML declarations in all their documents. Such a declaration is required
587when the character encoding of the document is other than the default UTF-8 or
588UTF-16.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]589
590<h3><a name="well-formed" id="well-formed">3.1.2 Using XHTML with
591other namespaces</a></h3>
592
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]593<p>The XHTML namespace may be used with other XML namespaces
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]594as per <a href="#ref-xmlns">[XMLNAMES]</a>, although such
595documents are not strictly conforming XHTML 1.0 documents as
596defined above. Future work by W3C will address ways to specify
597conformance for documents involving multiple namespaces.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]598
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]599<p>The following example shows the way in which XHTML 1.0 could
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]600be used in conjunction with the MathML Recommendation:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]601
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]602<div class="good">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]603<pre>
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]604&lt;html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"&gt;
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]605 &lt;head&gt;
606 &lt;title&gt;A Math Example&lt;/title&gt;
607 &lt;/head&gt;
608 &lt;body&gt;
609 &lt;p&gt;The following is MathML markup:&lt;/p&gt;
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]610 &lt;math xmlns="http://www.w3.org/1998/Math/MathML"&gt;
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]611 &lt;apply&gt; &lt;log/&gt;
612 &lt;logbase&gt;
613 &lt;cn&gt; 3 &lt;/cn&gt;
614 &lt;/logbase&gt;
615 &lt;ci&gt; x &lt;/ci&gt;
616 &lt;/apply&gt;
617 &lt;/math&gt;
618 &lt;/body&gt;
619&lt;/html&gt;
620</pre>
621</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]622
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]623<p>The following example shows the way in which XHTML 1.0 markup
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]624could be incorporated into another XML namespace:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]625
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]626<div class="good">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]627<pre>
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]628&lt;?xml version="1.0" encoding="UTF-8"?&gt;
629&lt;!-- initially, the default namespace is "books" --&gt;
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]630&lt;book xmlns='urn:loc.gov:books'
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]631 xmlns:isbn='urn:ISBN:0-395-36341-6' xml:lang="en" lang="en"&gt;
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]632 &lt;title&gt;Cheaper by the Dozen&lt;/title&gt;
633 &lt;isbn:number&gt;1568491379&lt;/isbn:number&gt;
634 &lt;notes&gt;
635 &lt;!-- make HTML the default namespace for a hypertext commentary --&gt;
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]636 &lt;p xmlns='http://www.w3.org/1999/xhtml'&gt;
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]637 This is also available &lt;a href="http://www.w3.org/"&gt;online&lt;/a&gt;.
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]638 &lt;/p&gt;
639 &lt;/notes&gt;
640&lt;/book&gt;
641</pre>
642</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]643
644<h2><a name="uaconf" id="uaconf">3.2 User Agent
645Conformance</a></h2>
646
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]647<p>A conforming user agent must meet all of the following
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]648criteria:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]649
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]650<ol>
651<li>In order to be consistent with the XML 1.0 Recommendation <a href="#ref-xml">[XML]</a>, the user agent must parse and evaluate
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]652an XHTML document for well-formedness. If the user agent claims
653to be a validating user agent, it must also validate documents
654against their referenced DTDs according to <a href="#ref-xml">
655[XML]</a>.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]656
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]657<li>When the user agent claims to support <a href="#facilities">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]658facilities</a> defined within this specification or required by
659this specification through normative reference, it must do so in
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]660ways consistent with the facilities' definition.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]661
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]662<li>When a user agent processes an XHTML document as generic XML,
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]663it shall only recognize attributes of type
664<code>ID</code> (e.g. the <code>id</code> attribute on most XHTML elements)
665as fragment identifiers.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]666
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]667<li>If a user agent encounters an element it does not recognize,
668it must render the element's content.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]669
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]670<li>If a user agent encounters an attribute it does not
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]671recognize, it must ignore the entire attribute specification
672(i.e., the attribute and its value).</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]673
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]674<li>If a user agent encounters an attribute value it doesn't
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]675recognize, it must use the default attribute value.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]676
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]677<li>If it encounters an entity reference (other than one
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]678of the predefined entities) for which the User Agent has
679processed no declaration (which could happen if the declaration
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]680is in the external subset which the User Agent hasn't read), the entity
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]681reference should be rendered as the characters (starting
682with the ampersand and ending with the semi-colon) that
683make up the entity reference.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]684
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]685<li>When rendering content, User Agents that encounter
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]686characters or character entity references that are recognized but not renderable should display the document in such a way that it is obvious to the user that normal rendering has not taken place.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]687
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]688<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]689The following characters are defined in [XML] as whitespace characters:
690
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]691<ul>
692<li>Space (&amp;#x0020;)</li>
693<li>Tab (&amp;#x0009;)</li>
694<li>Carriage return (&amp;#x000D;)</li>
695<li>Line feed (&amp;#x000A;)</li>
696</ul>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]697
698<p>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]699The XML processor normalizes different system's line end codes into one
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]700single line-feed character, that is passed up to the application. The XHTML
701user agent in addition, must treat the following characters as whitespace:
702</p>
703
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]704<ul>
705<li>Form feed (&amp;#x000C;)</li>
706<li>Zero-width space (&amp;#x200B;)</li>
707</ul>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]708
709<p>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]710In elements where the 'xml:space' attribute is set to 'preserve', the user
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]711agent must leave all whitespace characters intact (with the exception of
712leading and trailing whitespace characters, which should be removed).
713Otherwise, whitespace
714is handled according to the following rules:
715</p>
716
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]717<ul>
718<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]719All whitespace surrounding block elements should be removed.
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]720</li>
721<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]722Comments are removed entirely and do not affect whitespace handling. One
723whitespace character on either side of a comment is treated as two white
724space characters.
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]725</li>
726<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]727Leading and trailing whitespace inside a block element must be removed.
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]728</li>
729<li>Line feed characters within a block element must be converted into a
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]730space (except when the 'xml:space' attribute is set to 'preserve').
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]731</li>
732<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]733A sequence of white space characters must be reduced to a single space
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]734character (except when the 'xml:space' attribute is set to 'preserve').
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]735</li>
736<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]737With regard to rendition,
738the User Agent should render the content in a
739manner appropriate to the language in which the content is written.
740In languages whose primary script is Latinate, the ASCII space
741character is typically used to encode both grammatical word boundaries and
742typographic whitespace; in languages whose script is related to Nagari
743(e.g., Sanskrit, Thai, etc.), grammatical boundaries may be encoded using
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]744the ZW 'space' character, but will not typically be represented by
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]745typographic whitespace in rendered output; languages using Arabiform scripts
746may encode typographic whitespace using a space character, but may also use
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]747the ZW space character to delimit 'internal' grammatical boundaries (what
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]748look like words in Arabic to an English eye frequently encode several words,
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]749e.g. 'kitAbuhum' = 'kitAbu-hum' = 'book them' == their book); and languages
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]750in the Chinese script tradition typically neither encode such delimiters nor
751use typographic whitespace in this way.
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]752</li>
753</ul>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]754
755<p>Whitespace in attribute values is processed according to <a href="#ref-xml">[XML]</a>.</p>
756</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]757</ol>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]758
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]759<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]760<h1><a name="diffs" id="diffs">4. Differences with HTML
7614.0</a></h1>
762
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]763<p>Due to the fact that XHTML is an XML application, certain
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]764practices that were perfectly legal in SGML-based HTML 4.0 <a href="#ref-html4">[HTML]</a> must be changed.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]765
766<h2><a name="h-4.1" id="h-4.1">4.1 Documents must be
767well-formed</a></h2>
768
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]769<p><a href="#wellformed">Well-formedness</a> is a new concept
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]770introduced by <a href="#ref-xml">[XML]</a>. Essentially this
771means that all elements must either have closing tags or be
772written in a special form (as described below), and that all the
773elements must nest.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]774
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]775<p>Although overlapping is illegal in SGML, it was widely
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]776tolerated in existing browsers.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]777
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]778<div class="good">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]779<p><strong><em>CORRECT: nested elements.</em></strong></p>
780
781<p>&lt;p&gt;here is an emphasized
782&lt;em&gt;paragraph&lt;/em&gt;.&lt;/p&gt;</p>
783</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]784
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]785<div class="bad">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]786<p><strong><em>INCORRECT: overlapping elements</em></strong></p>
787
788<p>&lt;p&gt;here is an emphasized
789&lt;em&gt;paragraph.&lt;/p&gt;&lt;/em&gt;</p>
790</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]791
792<h2><a name="h-4.2" id="h-4.2">4.2 Element and attribute
793names must be in lower case</a></h2>
794
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]795<p>XHTML documents must use lower case for all HTML element and
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]796attribute names. This difference is necessary because XML is
797case-sensitive e.g. &lt;li&gt; and &lt;LI&gt; are different
798tags.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]799
800<h2><a name="h-4.3" id="h-4.3">4.3 For non-empty elements,
801end tags are required</a></h2>
802
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]803<p>In SGML-based HTML 4.0 certain elements were permitted to omit
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]804the end tag; with the elements that followed implying closure.
805This omission is not permitted in XML-based XHTML. All elements
806other than those declared in the DTD as <code>EMPTY</code> must
807have an end tag.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]808
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]809<div class="good">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]810<p><strong><em>CORRECT: terminated elements</em></strong></p>
811
812<p>&lt;p&gt;here is a paragraph.&lt;/p&gt;&lt;p&gt;here is
813another paragraph.&lt;/p&gt;</p>
814</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]815
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]816<div class="bad">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]817<p><strong><em>INCORRECT: unterminated elements</em></strong></p>
818
819<p>&lt;p&gt;here is a paragraph.&lt;p&gt;here is another
820paragraph.</p>
821</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]822
823<h2><a name="h-4.4" id="h-4.4">4.4 Attribute values must
824always be quoted</a></h2>
825
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]826<p>All attribute values must be quoted, even those which appear
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]827to be numeric.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]828
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]829<div class="good">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]830<p><strong><em>CORRECT: quoted attribute values</em></strong></p>
831
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]832<p>&lt;table rows="3"&gt;</p>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]833</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]834
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]835<div class="bad">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]836<p><strong><em>INCORRECT: unquoted attribute values</em></strong></p>
837
838<p>&lt;table rows=3&gt;</p>
839</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]840
841<h2><a name="h-4.5" id="h-4.5">4.5 Attribute
842Minimization</a></h2>
843
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]844<p>XML does not support attribute minimization. Attribute-value
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]845pairs must be written in full. Attribute names such as <code>
846compact</code> and <code>checked</code> cannot occur in elements
847without their value being specified.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]848
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]849<div class="good">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]850<p><strong><em>CORRECT: unminimized attributes</em></strong></p>
851
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]852<p>&lt;dl compact="compact"&gt;</p>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]853</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]854
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]855<div class="bad">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]856<p><strong><em>INCORRECT: minimized attributes</em></strong></p>
857
858<p>&lt;dl compact&gt;</p>
859</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]860
861<h2><a name="h-4.6" id="h-4.6">4.6 Empty Elements</a></h2>
862
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]863<p>Empty elements must either have an end tag or the start tag must end with <code>/&gt;</code>. For instance,
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]864<code>&lt;br/&gt;</code> or <code>&lt;hr&gt;&lt;/hr&gt;</code>. See <a href="#guidelines">HTML Compatibility Guidelines</a> for information on ways to
865ensure this is backward compatible with HTML 4.0 user agents.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]866
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]867<div class="good">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]868<p><strong><em>CORRECT: terminated empty tags</em></strong></p>
869
870<p>&lt;br/&gt;&lt;hr/&gt;</p>
871</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]872
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]873<div class="bad">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]874<p><strong><em>INCORRECT: unterminated empty tags</em></strong></p>
875
876<p>&lt;br&gt;&lt;hr&gt;</p>
877</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]878
879<h2><a name="h-4.7" id="h-4.7">4.7 Whitespace handling in
880attribute values</a></h2>
881
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]882<p>In attribute values, user agents will strip leading and
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]883trailing whitespace from attribute values and map sequences
884of one or more whitespace characters (including line breaks) to
885a single inter-word space (an ASCII space character for western
886scripts). See <a href="http://www.w3.org/TR/REC-xml#AVNormalize">
887Section 3.3.3</a> of <a href="#ref-xml">[XML]</a>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]888
889<h2><a name="h-4.8" id="h-4.8">4.8 Script and Style
890elements</a></h2>
891
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]892<p>In XHTML, the script and style elements are declared as having
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]893<code>#PCDATA</code> content. As a result, <code>&lt;</code> and
894<code>&amp;</code> will be treated as the start of markup, and
895entities such as <code>&amp;lt;</code> and <code>&amp;amp;</code>
896will be recognized as entity references by the XML processor to
897<code>&lt;</code> and <code>&amp;</code> respectively. Wrapping
898the content of the script or style element within a <code>
899CDATA</code> marked section avoids the expansion of these
900entities.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]901
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]902<div class="good">
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]903<pre>
904&lt;script&gt;
905 &lt;![CDATA[
906 ... unescaped script content ...
907 ]]&gt;
908 &lt;/script&gt;
909</pre>
910</div>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]911
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]912<p><code>CDATA</code> sections are recognized by the XML
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]913processor and appear as nodes in the Document Object Model, see
914<a href="http://www.w3.org/TR/REC-DOM-Level-1/level-one-core.html#ID-E067D597">
915Section 1.3</a> of the DOM Level 1 Recommendation <a href="#ref-dom">[DOM]</a>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]916
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]917<p>An alternative is to use external script and style
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]918documents.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]919
920<h2><a name="h-4.9" id="h-4.9">4.9 SGML exclusions</a></h2>
921
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]922<p>SGML gives the writer of a DTD the ability to exclude specific
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]923elements from being contained within an element. Such
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]924prohibitions (called "exclusions") are not possible in XML.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]925
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]926<p>For example, the HTML 4.0 Strict DTD forbids the nesting of an
927'<code>a</code>' element within another '<code>a</code>' element
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]928to any descendant depth. It is not possible to spell out such
929prohibitions in XML. Even though these prohibitions cannot be
930defined in the DTD, certain elements should not be nested. A
931summary of such elements and the elements that should not be
932nested in them is found in the normative <a href="#prohibitions">
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]933Appendix&#xA0;B</a>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]934
935<h2><a name="h-4.10" id="h-4.10">4.10 The elements with 'id' and 'name'
936attributes</a></h2>
937
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]938<p>HTML 4.0 defined the <code>name</code> attribute for the elements
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]939<code>a</code>,
940<code>applet</code>, <code>frame</code>,
941<code>iframe</code>, <code>img</code>, and <code>map</code>.
942HTML 4.0 also introduced
943the <code>id</code> attribute. Both of these attributes are designed to be
944used as fragment identifiers.</p>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]945<p>In XML, fragment identifiers are of type <code>ID</code>, and
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]946there can only be a single attribute of type <code>ID</code> per element.
947Therefore, in XHTML 1.0 the <code>id</code>
948attribute is defined to be of type <code>ID</code>. In order to
949ensure that XHTML 1.0 documents are well-structured XML documents, XHTML 1.0
950documents MUST use the <code>id</code> attribute when defining fragment
951identifiers, even on elements that historically have also had a
952<code>name</code> attribute.
953See the <a href="#guidelines">HTML Compatibility
954Guidelines</a> for information on ensuring such anchors are backwards
955compatible when serving XHTML documents as media type <code>text/html</code>.
956</p>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]957<p>Note that in XHTML 1.0, the <code>name</code> attribute of these
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]958elements is formally deprecated, and will be removed in a
959subsequent version of XHTML.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]960
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]961<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]962<h1><a name="issues" id="issues">5. Compatibility Issues</a></h1>
963
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]964<p>Although there is no requirement for XHTML 1.0 documents to be
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]965compatible with existing user agents, in practice this is easy to
966accomplish. Guidelines for creating compatible documents can be
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]967found in <a href="#guidelines">Appendix&#xA0;C</a>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]968
969<h2><a name="media" id="media">5.1 Internet Media Type</a></h2>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]970<p>As of the publication of this recommendation, the general
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]971recommended MIME labeling for XML-based applications
972has yet to be resolved.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]973
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]974<p>However, XHTML Documents which follow the guidelines set forth
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]975in <a href="#guidelines">Appendix C</a>, "HTML Compatibility Guidelines" may be
976labeled with the Internet Media Type "text/html", as they
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]977are compatible with most HTML browsers. This document
978makes no recommendation about MIME labeling of other
979XHTML documents.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]980
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]981<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]982<h1><a name="future" id="future">6. Future Directions</a></h1>
983
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]984<p>XHTML 1.0 provides the basis for a family of document types
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]985that will extend and subset XHTML, in order to support a wide
986range of new devices and applications, by defining modules and
987specifying a mechanism for combining these modules. This
988mechanism will enable the extension and sub-setting of XHTML 1.0
989in a uniform way through the definition of new modules.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]990
991<h2><a name="mods" id="mods">6.1 Modularizing HTML</a></h2>
992
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]993<p>As the use of XHTML moves from the traditional desktop user
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]994agents to other platforms, it is clear that not all of the XHTML
995elements will be required on all platforms. For example a hand
996held device or a cell-phone may only support a subset of XHTML
997elements.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]998
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]999<p>The process of modularization breaks XHTML up into a series of
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1000smaller element sets. These elements can then be recombined to
1001meet the needs of different communities.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1002
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1003<p>These modules will be defined in a later W3C document.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1004
1005<h2><a name="extensions" id="extensions">6.2 Subsets and
1006Extensibility</a></h2>
1007
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1008<p>Modularization brings with it several advantages:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1009
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1010<ul>
1011<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1012<p>It provides a formal mechanism for sub-setting XHTML.</p>
1013</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1014
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1015<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1016<p>It provides a formal mechanism for extending XHTML.</p>
1017</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1018
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1019<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1020<p>It simplifies the transformation between document types.</p>
1021</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1022
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1023<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1024<p>It promotes the reuse of modules in new document types.</p>
1025</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1026</ul>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1027
1028<h2><a name="profiles" id="profiles">6.3 Document
1029Profiles</a></h2>
1030
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1031<p>A document profile specifies the syntax and semantics of a set
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1032of documents. Conformance to a document profile provides a basis
1033for interoperability guarantees. The document profile specifies
1034the facilities required to process documents of that type, e.g.
1035which image formats can be used, levels of scripting, style sheet
1036support, and so on.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1037
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1038<p>For product designers this enables various groups to define
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1039their own standard profile.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1040
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1041<p>For authors this will obviate the need to write several
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1042different versions of documents for different clients.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1043
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1044<p>For special groups such as chemists, medical doctors, or
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1045mathematicians this allows a special profile to be built using
1046standard HTML elements plus a group of elements geared to the
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1047specialist's needs.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1048
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1049<!--OddPage-->
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1050<h1><a name="appendices" id="appendices"></a>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1051<a name="dtds" id="dtds">Appendix A. DTDs</a></h1>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1052
1053<p><b>This appendix is normative.</b></p>
1054
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1055<p>These DTDs and entity sets form a normative part of this
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1056specification. The complete set of DTD files together with an XML
1057declaration and SGML Open Catalog is included in the <a href="xhtml1.zip">zip file</a> for this specification.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1058
1059<h2><a name="h-A1" id="h-A1">A.1 Document Type
1060Definitions</a></h2>
1061
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1062<p>These DTDs approximate the HTML 4.0 DTDs. It is likely that
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1063when the DTDs are modularized, a method of DTD construction will
1064be employed that corresponds more closely to HTML 4.0.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1065
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1066<ul>
1067<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1068<p><a href="DTD/xhtml1-strict.dtd" type="text/plain">
1069XHTML-1.0-Strict</a></p>
1070</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1071
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1072<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1073<p><a href="DTD/xhtml1-transitional.dtd" type="text/plain">
1074XHTML-1.0-Transitional</a></p>
1075</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1076
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1077<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1078<p><a href="DTD/xhtml1-frameset.dtd" type="text/plain">
1079XHTML-1.0-Frameset</a></p>
1080</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1081</ul>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1082
1083<h2><a name="h-A2" id="h-A2">A.2 Entity Sets</a></h2>
1084
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1085<p>The XHTML entity sets are the same as for HTML 4.0, but have
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1086been modified to be valid XML 1.0 entity declarations. Note the
1087entity for the Euro currency sign (<code>&amp;euro;</code> or
1088<code>&amp;#8364;</code> or <code>&amp;#x20AC;</code>) is defined
1089as part of the special characters.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1090
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1091<ul>
1092<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1093<p><a href="DTD/xhtml-lat1.ent">Latin-1 characters</a></p>
1094</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1095
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1096<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1097<p><a href="DTD/xhtml-special.ent">Special characters</a></p>
1098</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1099
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1100<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1101<p><a href="DTD/xhtml-symbol.ent">Symbols</a></p>
1102</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1103</ul>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1104
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1105<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1106<h1><a name="prohibitions" id="prohibitions">Appendix B. Element
1107Prohibitions</a></h1>
1108
1109<p><b>This appendix is normative.</b></p>
1110
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1111<p>The following elements have prohibitions on which elements
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1112they can contain (see <a href="#h-4.9">Section 4.9</a>). This
1113prohibition applies to all depths of nesting, i.e. it contains
1114all the descendant elements.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1115
1116<dl><dt><code class="tag">a</code></dt>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1117<dd>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1118cannot contain other <code>a</code> elements.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1119<dt><code class="tag">pre</code></dt>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1120<dd>cannot contain the <code>img</code>, <code>object</code>,
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1121<code>big</code>, <code>small</code>, <code>sub</code>, or <code>
1122sup</code> elements.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1123
1124<dt><code class="tag">button</code></dt>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1125<dd>cannot contain the <code>input</code>, <code>select</code>,
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1126<code>textarea</code>, <code>label</code>, <code>button</code>,
1127<code>form</code>, <code>fieldset</code>, <code>iframe</code> or
1128<code>isindex</code> elements.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1129<dt><code class="tag">label</code></dt>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1130<dd>cannot contain other <code class="tag">label</code> elements.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1131<dt><code class="tag">form</code></dt>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1132<dd>cannot contain other <code>form</code> elements.</dd>
1133</dl>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1134
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1135<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1136<h1><a name="guidelines" id="guidelines">Appendix C.
1137HTML Compatibility Guidelines</a></h1>
1138
1139<p><b>This appendix is informative.</b></p>
1140
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1141<p>This appendix summarizes design guidelines for authors who
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1142wish their XHTML documents to render on existing HTML user
1143agents.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1144
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1145<h2>C.1 Processing Instructions</h2>
1146<p>Be aware that processing instructions are rendered on some
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1147user agents. However, also note that when the XML declaration is not included
1148in a document, the document can only use the default character encodings UTF-8
1149or UTF-16.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1150
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1151<h2>C.2 Empty Elements</h2>
1152<p>Include a space before the trailing <code>/</code> and <code>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1153&gt;</code> of empty elements, e.g. <code class="greenmono">
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1154&lt;br&#xA0;/&gt;</code>, <code class="greenmono">
1155&lt;hr&#xA0;/&gt;</code> and <code class="greenmono">&lt;img
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1156src="karen.jpg" alt="Karen"&#xA0;/&gt;</code>. Also, use the
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1157minimized tag syntax for empty elements, e.g. <code class="greenmono">&lt;br /&gt;</code>, as the alternative syntax <code class="greenmono">&lt;br&gt;&lt;/br&gt;</code> allowed by XML
1158gives uncertain results in many existing user agents.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1159
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1160<h2>C.3 Element Minimization and Empty Element Content</h2>
1161<p>Given an empty instance of an element whose content model is
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1162not <code>EMPTY</code> (for example, an empty title or paragraph)
1163do not use the minimized form (e.g. use <code class="greenmono">
1164&lt;p&gt; &lt;/p&gt;</code> and not <code class="greenmono">
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1165&lt;p&#xA0;/&gt;</code>).</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1166
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1167<h2>C.4 Embedded Style Sheets and Scripts</h2>
1168<p>Use external style sheets if your style sheet uses <code>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1169&lt;</code> or <code>&amp;</code> or <code>]]&gt;</code> or <code>--</code>. Use
1170external scripts if your script uses <code>&lt;</code> or <code>
1171&amp;</code> or <code>]]&gt;</code> or <code>--</code>. Note that XML parsers
1172are permitted to silently remove the contents of comments. Therefore, the historical
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1173practice of "hiding" scripts and style sheets within comments to make the
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1174documents backward compatible is likely to not work as expected in XML-based
1175implementations.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1176
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1177<h2>C.5 Line Breaks within Attribute Values</h2>
1178<p>Avoid line breaks and multiple whitespace characters within
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1179attribute values. These are handled inconsistently by user
1180agents.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1181
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1182<h2>C.6 Isindex</h2>
1183<p>Don't include more than one <code>isindex</code> element in
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1184the document <code>head</code>. The <code>isindex</code> element
1185is deprecated in favor of the <code>input</code> element.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1186
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1187<h2>C.7 The <code>lang</code> and <code>xml:lang</code> Attributes</h2>
1188<p>Use both the <code>lang</code> and <code>xml:lang</code>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1189attributes when specifying the language of an element. The value
1190of the <code>xml:lang</code> attribute takes precedence.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1191
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1192<h2>C.8 Fragment Identifiers</h2>
1193<p>In XML, <abbr title="Uniform Resource Identifiers">URIs</abbr> [<a href="#ref-rfc2396">RFC2396</a>] that end with fragment identifiers of the form
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1194<code>"#foo"</code> do not refer to elements with an attribute
1195<code>name="foo"</code>; rather, they refer to elements with an
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1196attribute defined to be of type <code>ID</code>, e.g., the <code>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1197id</code> attribute in HTML 4.0. Many existing HTML clients don't
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1198support the use of <code>ID</code>-type attributes in this way,
1199so identical values may be supplied for both of these attributes to ensure
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1200maximum forward and backward compatibility (e.g., <code class="greenmono">&lt;a id="foo" name="foo"&gt;...&lt;/a&gt;</code>).</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1201
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1202<p>Further, since the set of
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1203legal values for attributes of type <code>ID</code> is much smaller than
1204for those of type <code>CDATA</code>, the type of the <code>name</code>
1205attribute has been changed to <code>NMTOKEN</code>. This attribute is
1206constrained such that it can only have the same values as type
1207<code>ID</code>, or as the <code>Name</code> production in XML 1.0 Section
12082.5, production 5. Unfortunately, this constraint cannot be expressed in the
1209XHTML 1.0 DTDs. Because of this change, care must be taken when
1210converting existing HTML documents. The values of these attributes
1211must be unique within the document, valid, and any references to these
1212fragment identifiers (both
1213internal and external) must be updated should the values be changed during
1214conversion.</p>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1215<p>Finally, note that XHTML 1.0 has deprecated the
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1216<code>name</code> attribute of the <code>a</code>, <code>applet</code>, <code>frame</code>, <code>iframe</code>, <code>img</code>, and <code>map</code>
1217elements, and it will be
1218removed from XHTML in subsequent versions.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1219
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1220<h2>C.9 Character Encoding</h2>
1221<p>To specify a character encoding in the document, use both the
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1222encoding attribute specification on the xml declaration (e.g.
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1223<code class="greenmono">&lt;?xml version="1.0"
1224encoding="EUC-JP"?&gt;</code>) and a meta http-equiv statement
1225(e.g. <code class="greenmono">&lt;meta http-equiv="Content-type"
1226content='text/html; charset="EUC-JP"'&#xA0;/&gt;</code>). The
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1227value of the encoding attribute of the xml processing instruction
1228takes precedence.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1229
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1230<h2>C.10 Boolean Attributes</h2>
1231<p>Some HTML user agents are unable to interpret boolean
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1232attributes when these appear in their full (non-minimized) form,
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1233as required by XML 1.0. Note this problem doesn't effect user
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1234agents compliant with HTML 4.0. The following attributes are
1235involved: <code>compact</code>, <code>nowrap</code>, <code>
1236ismap</code>, <code>declare</code>, <code>noshade</code>, <code>
1237checked</code>, <code>disabled</code>, <code>readonly</code>,
1238<code>multiple</code>, <code>selected</code>, <code>
1239noresize</code>, <code>defer</code>.</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1240
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1241<h2>C.11 Document Object Model and XHTML</h2>
1242<p>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1243The Document Object Model level 1 Recommendation [<a href="#ref-dom">DOM</a>]
1244defines document object model interfaces for XML and HTML 4.0. The HTML 4.0
1245document object model specifies that HTML element and attribute names are
1246returned in upper-case. The XML document object model specifies that
1247element and attribute names are returned in the case they are specified. In
1248XHTML 1.0, elements and attributes are specified in lower-case. This apparent difference can be
1249addressed in two ways:
1250</p>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1251<ol>
1252<li>Applications that access XHTML documents served as Internet media type
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1253<code>text/html</code>
1254via the <abbr title="Document Object Model">DOM</abbr> can use the HTML DOM,
1255and can rely upon element and attribute names being returned in
1256upper-case from those interfaces.</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1257<li>Applications that access XHTML documents served as Internet media types
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1258<code>text/xml</code> or <code>application/xml</code>
1259can also use the XML DOM. Elements and attributes will be returned in lower-case.
1260Also, some XHTML elements may or may
1261not appear
1262in the object tree because they are optional in the content model
1263(e.g. the <code>tbody</code> element within
1264<code>table</code>). This occurs because in HTML 4.0 some elements were
1265permitted to be minimized such that their start and end tags are both omitted
1266(an SGML feature).
1267This is not possible in XML. Rather than require document authors to insert
1268extraneous elements, XHTML has made the elements optional.
1269Applications need to adapt to this
1270accordingly.</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1271</ol>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1272
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1273<h2>C.12 Using Ampersands in Attribute Values</h2>
1274<p>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1275When an attribute value contains an ampersand, it must be expressed as a character
1276entity reference
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1277(e.g. "<code>&amp;amp;</code>"). For example, when the
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1278<code>href</code> attribute
1279of the <code>a</code> element refers to a
1280CGI script that takes parameters, it must be expressed as
1281<code>http://my.site.dom/cgi-bin/myscript.pl?class=guest&amp;amp;name=user</code>
1282rather than as
1283<code>http://my.site.dom/cgi-bin/myscript.pl?class=guest&amp;name=user</code>.
1284</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1285
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1286<h2>C.13 Cascading Style Sheets (CSS) and XHTML</h2>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1287
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1288<p>The Cascading Style Sheets level 2 Recommendation [<a href="#ref-css2">CSS2</a>] defines style
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1289properties which are applied to the parse tree of the HTML or XML
1290document. Differences in parsing will produce different visual or
1291aural results, depending on the selectors used. The following hints
1292will reduce this effect for documents which are served without
1293modification as both media types:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1294
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1295<ol>
1296<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1297CSS style sheets for XHTML should use lower case element and
1298attribute names.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1299
1300
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1301<li>In tables, the tbody element will be inferred by the parser of an
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1302HTML user agent, but not by the parser of an XML user agent. Therefore
1303you should always explicitely add a tbody element if it is referred to
1304in a CSS selector.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1305
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1306<li>Within the XHTML name space, user agents are expected to
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1307recognize the "id" attribute as an attribute of type ID.
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1308Therefore, style sheets should be able to continue using the
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1309shorthand "#" selector syntax even if the user agent does not read
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1310the DTD.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1311
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1312<li>Within the XHTML name space, user agents are expected to
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1313recognize the "class" attribute. Therefore, style sheets should be
1314able to continue using the shorthand "." selector syntax.</li>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1315
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1316<li>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1317CSS defines different conformance rules for HTML and XML documents;
1318be aware that the HTML rules apply to XHTML documents delivered as
1319HTML and the XML rules apply to XHTML documents delivered as XML.</li>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1320</ol>
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1321<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1322<h1><a name="acks" id="acks">Appendix D.
1323Acknowledgements</a></h1>
1324
1325<p><b>This appendix is informative.</b></p>
1326
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1327<p>This specification was written with the participation of the
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1328members of the W3C HTML working group:</p>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1329
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1330<dl>
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1331<dd>Steven Pemberton, CWI (HTML Working Group Chair)<br />
1332Murray Altheim, Sun Microsystems<br />
1333Daniel Austin, CNET: The Computer Network<br />
1334Frank Boumphrey, HTML Writers Guild<br />
1335John Burger, Mitre<br />
1336Andrew W. Donoho, IBM<br />
1337Sam Dooley, IBM<br />
1338Klaus Hofrichter, GMD<br />
1339Philipp Hoschka, W3C<br />
1340Masayasu Ishikawa, W3C<br />
1341Warner ten Kate, Philips Electronics<br />
1342Peter King, Phone.com<br />
1343Paula Klante, JetForm<br />
1344Shin'ichi Matsui, W3C/Panasonic<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1345Shane McCarron, Applied Testing and Technology (The Open Group through August
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]13461999)<br />
1347Ann Navarro, HTML Writers Guild<br />
1348Zach Nies, Quark<br />
1349Dave Raggett, W3C/HP (W3C lead for HTML)<br />
1350Patrick Schmitz, Microsoft<br />
1351Sebastian Schnitzenbaumer, Stack Overflow<br />
1352Chris Wilson, Microsoft<br />
1353Ted Wugofski, Gateway 2000<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1354Dan Zigmond, WebTV Networks</dd>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1355</dl>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1356
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1357<!--OddPage-->
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1358<h1><a name="refs" id="refs">Appendix E. References</a></h1>
1359
1360<p><b>This appendix is informative.</b></p>
1361
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1362<dl>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1363
1364<dt><a name="ref-css2" id="ref-css2"><b>[CSS2]</b></a></dt>
1365
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1366<dd><a href="http://www.w3.org/TR/REC-CSS2">"Cascading Style Sheets, level 2 (CSS2) Specification"</a>, B.
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1367Bos, H. W. Lie, C. Lilley, I. Jacobs, 12 May 1998.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1368Available at: <a href="http://www.w3.org/TR/REC-CSS2">
1369http://www.w3.org/TR/REC-CSS2</a></dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1370
1371<dt><a name="ref-dom" id="ref-dom"><b>[DOM]</b></a></dt>
1372
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1373<dd><a href="http://www.w3.org/TR/REC-DOM-Level-1">"Document Object Model (DOM) Level 1 Specification"</a>, Lauren
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1374Wood <i>et al.</i>, 1 October 1998.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1375Available at: <a href="http://www.w3.org/TR/REC-DOM-Level-1">
1376http://www.w3.org/TR/REC-DOM-Level-1</a></dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1377
1378<dt><a name="ref-html4" id="ref-html4"><b>[HTML]</b></a></dt>
1379
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1380<dd><a href="http://www.w3.org/TR/1999/PR-html40-19990824">"HTML 4.01 Specification"</a>, D. Raggett, A. Le&#xA0;Hors, I.
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1381Jacobs, 24 August 1999.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1382Available at: <a href="http://www.w3.org/TR/1999/PR-html40-19990824">
1383http://www.w3.org/TR/1999/PR-html40-19990824</a></dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1384
1385<dt><a name="ref-posix" id="ref-posix"><b>[POSIX.1]</b></a></dt>
1386
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1387<dd>"ISO/IEC 9945-1:1990 Information Technology - Portable
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1388Operating System Interface (POSIX) - Part 1: System Application
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1389Program Interface (API) [C Language]", Institute of Electrical
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1390and Electronics Engineers, Inc, 1990.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1391
1392<dt><a name="ref-rfc2046" id="ref-rfc2046"><b>
1393[RFC2046]</b></a></dt>
1394
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1395<dd><a href="http://www.ietf.org/rfc/rfc2046.txt">"RFC2046: Multipurpose Internet Mail Extensions (MIME) Part
1396Two: Media Types"</a>, N. Freed and N. Borenstein, November
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]13971996.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1398Available at <a href="http://www.ietf.org/rfc/rfc2046.txt">
1399http://www.ietf.org/rfc/rfc2046.txt</a>. Note that this RFC
1400obsoletes RFC1521, RFC1522, and RFC1590.</dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1401
1402<dt><a name="ref-rfc2119" id="ref-rfc2119"><b>
1403[RFC2119]</b></a></dt>
1404
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1405<dd><a href="http://www.ietf.org/rfc/rfc2119.txt">"RFC2119: Key words for use in RFCs to Indicate Requirement
1406Levels"</a>, S. Bradner, March 1997.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1407Available at: <a href="http://www.ietf.org/rfc/rfc2119.txt">
1408http://www.ietf.org/rfc/rfc2119.txt</a></dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1409
1410<dt><a name="ref-rfc2376" id="ref-rfc2376"><b>
1411[RFC2376]</b></a></dt>
1412
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1413<dd><a href="http://www.ietf.org/rfc/rfc2376.txt">"RFC2376: XML Media Types"</a>, E. Whitehead, M. Murata, July
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]14141998.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1415Available at: <a href="http://www.ietf.org/rfc/rfc2376.txt">
1416http://www.ietf.org/rfc/rfc2376.txt</a></dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1417
1418<dt><a name="ref-rfc2396" id="ref-rfc2396"><b>
1419[RFC2396]</b></a></dt>
1420
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1421<dd><a href="http://www.ietf.org/rfc/rfc2396.txt">"RFC2396: Uniform Resource Identifiers (URI): Generic
1422Syntax"</a>, T. Berners-Lee, R. Fielding, L. Masinter, August
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]14231998.<br />
1424This document updates RFC1738 and RFC1808.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1425Available at: <a href="http://www.ietf.org/rfc/rfc2396.txt">
1426http://www.ietf.org/rfc/rfc2396.txt</a></dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1427
1428<dt><a name="ref-xml" id="ref-xml"><b>[XML]</b></a></dt>
1429
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1430<dd><a href="http://www.w3.org/TR/REC-xml">"Extensible Markup Language (XML) 1.0 Specification"</a>, T.
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1431Bray, J. Paoli, C. M. Sperberg-McQueen, 10 February 1998.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1432Available at: <a href="http://www.w3.org/TR/REC-xml">
1433http://www.w3.org/TR/REC-xml</a></dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1434
1435<dt><a name="ref-xmlns" id="ref-xmlns"><b>[XMLNAMES]</b></a></dt>
1436
Daniel Veillard8265a182003-06-13 10:05:56 +0000[diff] [blame]1437<dd><a href="http://www.w3.org/TR/REC-xml-names">"Namespaces in XML"</a>, T. Bray, D. Hollander, A. Layman, 14
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1438January 1999.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1439XML namespaces provide a simple method for qualifying names used
1440in XML documents by associating them with namespaces identified
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1441by URI.<br />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1442Available at: <a href="http://www.w3.org/TR/REC-xml-names">
1443http://www.w3.org/TR/REC-xml-names</a></dd>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1444
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1445</dl>
Daniel Veillard2f362242001-03-02 17:36:21 +0000[diff] [blame]1446<p><a href="http://www.w3.org/WAI/WCAG1AAA-Conformance" title="Explanation of Level Triple-A Conformance">
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1447<img height="32" width="88" src="wcag1AAA.gif" alt="Level Triple-A conformance icon, W3C-WAI Web Content Accessibility Guidelines 1.0" /></a></p>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1448<div class="navbar">
Daniel Veillardd5c2f922002-11-21 14:10:52 +0000[diff] [blame]1449 <hr />
Daniel Veillard686d6b62000-01-03 11:08:02 +0000[diff] [blame]1450 <a href="#toc">table of contents</a>
1451</div>
Daniel Veillard75c29212000-03-14 18:33:47 +0000[diff] [blame]1452</body>
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