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diff --git a/test/valid/xhtml1.xhtml b/test/valid/xhtml1.xhtml new file mode 100644 index 0000000..24d68f4 --- /dev/null +++ b/test/valid/xhtml1.xhtml @@ -0,0 +1,1505 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "dtds/xhtml1-strict.dtd"> +<?xml-stylesheet href="W3C-PR.css" type="text/css"?> +<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"> +<head> +<title>XHTML 1.0: The Extensible HyperText Markup +Language</title> +<link rel="stylesheet" +href="W3C-PR.css" type="text/css" /> +<style type="text/css"> +span.term { font-style: italic; color: rgb(0, 0, 192) } +code { + color: green; + font-family: monospace; + font-weight: bold; +} + +code.greenmono { + color: green; + font-family: monospace; + font-weight: bold; +} +.good { + border: solid green; + border-width: 2px; + color: green; + font-weight: bold; + margin-right: 5%; + margin-left: 0; +} +.bad { + border: solid red; + border-width: 2px; + margin-left: 0; + margin-right: 5%; + color: rgb(192, 101, 101); +} + +img { + color: white; + border: none; +} + +div.navbar { text-align: center; } +div.contents { + background-color: rgb(204,204,255); + padding: 0.5em; + border: none; + margin-right: 5%; +} +.tocline { list-style: none; } +table.exceptions { background-color: rgb(255,255,153); } +</style> +</head> +<body> +<div class="navbar"> + <a href="#toc">table of contents</a> + <hr /> +</div> +<div class="head"><p><a href="http://www.w3.org/"><img class="head" +src="w3c_home.gif" alt="W3C" /></a></p> + +<h1 class="head"><a name="title" id="title">XHTML</a><sup>™</sup> 1.0: +The Extensible HyperText Markup Language</h1> + +<h2>A Reformulation of HTML 4.0 in XML 1.0</h2> + +<h3>W3C Proposed Recommendation 10 December 1999</h3> + +<dl> +<dt>This version:</dt> + +<dd><a href= +"http://www.w3.org/TR/1999/PR-xhtml1-19991210"> +http://www.w3.org/TR/1999/PR-xhtml1-19991210</a> <br /> +(<a href="xhtml1.ps">Postscript version</a>, +<a href="xhtml1.pdf">PDF version</a>, +<a href="xhtml1.zip">ZIP archive</a>, or +<a href="xhtml1.tgz">Gzip'd TAR archive</a>) +</dd> + +<dt>Latest version:</dt> + +<dd><a href="http://www.w3.org/TR/xhtml1"> +http://www.w3.org/TR/xhtml1</a></dd> + +<dt>Previous versions:</dt> + +<dd><a href= +"http://www.w3.org/TR/1999/WD-xhtml1-19991124"> +http://www.w3.org/TR/1999/WD-xhtml1-19991124</a></dd> +<dd><a href= +"http://www.w3.org/TR/1999/PR-xhtml1-19990824"> +http://www.w3.org/TR/1999/PR-xhtml1-19990824</a></dd> + +<dt>Authors:</dt> + +<dd>See <a href="#acks">acknowledgements</a>.</dd> +</dl> + +<p class="copyright"><a href= +"http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"> +Copyright</a> © 1999 <a href="http://www.w3.org/">W3C</a><sup>®</sup> +(<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"> +liability</a>, <a href= +"http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks"> +trademark</a>, <a href= +"http://www.w3.org/Consortium/Legal/copyright-documents">document +use</a> and <a href= +"http://www.w3.org/Consortium/Legal/copyright-software">software +licensing</a> rules apply.</p> +<hr /> +</div> + +<h2 class="notoc">Abstract</h2> + +<p>This specification defines <abbr title="Extensible Hypertext Markup +Language">XHTML</abbr> 1.0, a reformulation of HTML +4.0 as an XML 1.0 application, and three <abbr title="Document Type +Definition">DTDs</abbr> corresponding to +the ones defined by HTML 4.0. The semantics of the elements and +their attributes are defined in the W3C Recommendation for HTML +4.0. These semantics provide the foundation for future +extensibility of XHTML. Compatibility with existing HTML user +agents is possible by following a small set of guidelines.</p> + +<h2>Status of this document</h2> + +<p><em>This section describes the status of this document at the time +of its publication. Other documents may supersede this document. The +latest status of this document series is maintained at the W3C.</em></p> + +<p>This specification is a Proposed Recommendation of the HTML Working Group. It is +a revision of the Proposed Recommendation dated <a +href= "http://www.w3.org/TR/1999/PR-xhtml1-19990824/">24 August +1999</a> incorporating changes as a result of comments from the Proposed +Recommendation review, and +comments and further deliberations of the W3C HTML Working Group. A +<a href="xhtml1-diff-19991210.html">diff-marked version</a> from the previous +proposed recommendation is available for comparison purposes.</p> + +<p>On 10 December 1999, this document enters a +<a href="http://www.w3.org/Consortium/Process/#RecsPR"> +Proposed Recommendation</a> review period. From that date until 8 January +2000, +W3C Advisory Committee representatives are encouraged +to review this specification and return comments in their completed +ballots to w3c-html-review@w3.org. Please send any comments of a +confidential nature in separate email to w3t-html@w3.org, which is +visible to the Team only.</p> + +<p>No sooner than 14 days after the end of the review period, the +Director will announce the document's disposition: it may become a W3C +Recommendation (possibly with minor changes), it may revert to Working +Draft status, or it may be dropped as a W3C work item.</p> + +<p>Publication as a Proposed Recommendation does not imply endorsement +by the W3C membership. This is still a draft document and may be +updated, replaced or obsoleted by other documents at any time. It is +inappropriate to cite W3C Proposed Recommendation as other than "work +in progress."</p> + +<p>This document has been produced as part of the <a href= +"http://www.w3.org/MarkUp/">W3C HTML Activity</a>. The goals of +the <a href="http://www.w3.org/MarkUp/Group/">HTML Working +Group</a> <i>(<a href="http://cgi.w3.org/MemberAccess/">members +only</a>)</i> are discussed in the <a href= +"http://www.w3.org/MarkUp/Group/HTMLcharter">HTML Working Group +charter</a> <i>(<a href="http://cgi.w3.org/MemberAccess/">members +only</a>)</i>.</p> + +<p>A list of current W3C Recommendations and other technical documents +can be found at <a +href="http://www.w3.org/TR">http://www.w3.org/TR</a>.</p> + +<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 +staff contact for work on HTML is <a href= "mailto:dsr@w3.org">Dave +Raggett</a>.</p> + +<p>Please report errors in this document to <a +href="mailto:www-html-editor@w3.org">www-html-editor@w3.org</a>.</p> + +<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> + +<h2 class="notoc"><a id="toc" name="toc">Contents</a></h2> + +<div class="contents"> +<ul class="toc"> +<li class="tocline">1. <a href="#xhtml">What is XHTML?</a> + +<ul class="toc"> +<li class="tocline">1.1 <a href="#html4">What is HTML 4.0?</a></li> + +<li class="tocline">1.2 <a href="#xml">What is XML?</a></li> + +<li class="tocline">1.3 <a href="#why">Why the need for XHTML?</a></li> +</ul> +</li> + +<li class="tocline">2. <a href="#defs">Definitions</a> + +<ul class="toc"> +<li class="tocline">2.1 <a href="#terms">Terminology</a></li> + +<li class="tocline">2.2 <a href="#general">General Terms</a></li> +</ul> +</li> + +<li class="tocline">3. <a href="#normative">Normative Definition of XHTML 1.0</a> + + +<ul class="toc"> +<li class="tocline">3.1 <a href="#docconf">Document Conformance</a></li> + +<li class="tocline">3.2 <a href="#uaconf">User Agent Conformance</a></li> +</ul> +</li> + +<li class="tocline">4. <a href="#diffs">Differences with HTML 4.0</a> + +</li> + +<li class="tocline">5. <a href="#issues">Compatibility Issues</a> + +<ul class="toc"> +<li class="tocline">5.1 <a href="#media">Internet Media Types</a></li> +</ul> +</li> + +<li class="tocline">6. <a href="#future">Future Directions</a> + +<ul class="toc"> +<li class="tocline">6.1 <a href="#mods">Modularizing HTML</a></li> + +<li class="tocline">6.2 <a href="#extensions">Subsets and Extensibility</a></li> + +<li class="tocline">6.3 <a href="#profiles">Document Profiles</a></li> +</ul> +</li> + +<li class="tocline"><a href="#dtds">Appendix A. DTDs</a></li> + +<li class="tocline"><a href="#prohibitions">Appendix B. Element +Prohibitions</a></li> + +<li class="tocline"><a href="#guidelines">Appendix C. HTML Compatibility Guidelines</a></li> + +<li class="tocline"><a href="#acks">Appendix D. Acknowledgements</a></li> + +<li class="tocline"><a href="#refs">Appendix E. References</a></li> +</ul> +</div> + +<!--OddPage--> +<h1><a name="xhtml" id="xhtml">1. What is XHTML?</a></h1> + +<p>XHTML is a family of current and future document types and modules that +reproduce, 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, +and ultimately are designed to work in conjunction with XML-based user agents. +The details of this family and its evolution are +discussed in more detail in the section on <a href="#future">Future +Directions</a>. </p> + +<p>XHTML 1.0 (this specification) is the first document type in the XHTML +family. It is a reformulation of the three HTML 4.0 document types as +applications of XML 1.0 <a href="#ref-xml"> [XML]</a>. It is intended +to be used as a language for content that is both XML-conforming and, if some +simple <a href="#guidelines">guidelines</a> are followed, +operates in HTML 4.0 conforming user agents. Developers who migrate +their content to XHTML 1.0 will realize the following benefits:</p> + +<ul> +<li>XHTML documents are XML conforming. As such, they are readily viewed, +edited, and validated with standard XML tools.</li> +<li>XHTML documents can be written to +to operate as well or better than they did before in existing +HTML 4.0-conforming user agents as well as in new, XHTML 1.0 conforming user +agents.</li> +<li>XHTML documents can utilize applications (e.g. scripts and applets) that rely +upon either the HTML Document Object Model or the XML Document Object Model <a +href="#ref-dom">[DOM]</a>.</li> +<li>As the XHTML family evolves, documents conforming to XHTML 1.0 will be more +likely to interoperate within and among various XHTML environments.</li> +</ul> + +<p>The XHTML family is the next step in the evolution of the Internet. By +migrating to XHTML today, content developers can enter the XML world with all +of its attendant benefits, while still remaining confident in their +content's backward and future compatibility.</p> + +<h2><a name="html4" id="html4">1.1 What is HTML 4.0?</a></h2> + +<p>HTML 4.0 <a href="#ref-html4">[HTML]</a> is an <abbr title="Standard +Generalized Markup Language">SGML</abbr> (Standard +Generalized Markup Language) application conforming to +International Standard <abbr title="Organization for International +Standardization">ISO</abbr> 8879, and is widely regarded as the +standard publishing language of the World Wide Web.</p> + +<p>SGML is a language for describing markup languages, +particularly those used in electronic document exchange, document +management, and document publishing. HTML is an example of a +language defined in SGML.</p> + +<p>SGML has been around since the middle 1980's and has remained +quite stable. Much of this stability stems from the fact that the +language is both feature-rich and flexible. This flexibility, +however, comes at a price, and that price is a level of +complexity that has inhibited its adoption in a diversity of +environments, including the World Wide Web.</p> + +<p>HTML, as originally conceived, was to be a language for the +exchange of scientific and other technical documents, suitable +for use by non-document specialists. HTML addressed the problem +of SGML complexity by specifying a small set of structural and +semantic tags suitable for authoring relatively simple documents. +In addition to simplifying the document structure, HTML added +support for hypertext. Multimedia capabilities were added +later.</p> + +<p>In a remarkably short space of time, HTML became wildly +popular and rapidly outgrew its original purpose. Since HTML's +inception, there has been rapid invention of new elements for use +within HTML (as a standard) and for adapting HTML to vertical, +highly specialized, markets. This plethora of new elements has +led to compatibility problems for documents across different +platforms.</p> + +<p>As the heterogeneity of both software and platforms rapidly +proliferate, it is clear that the suitability of 'classic' HTML +4.0 for use on these platforms is somewhat limited.</p> + +<h2><a name="xml" id="xml">1.2 What is XML?</a></h2> + +<p>XML<sup>™</sup> is the shorthand for Extensible Markup +Language, and is an acronym of Extensible Markup Language <a +href="#ref-xml">[XML]</a>.</p> + +<p>XML was conceived as a means of regaining the power and +flexibility of SGML without most of its complexity. Although a +restricted form of SGML, XML nonetheless preserves most of SGML's +power and richness, and yet still retains all of SGML's commonly +used features.</p> + +<p>While retaining these beneficial features, XML removes many of +the more complex features of SGML that make the authoring and +design of suitable software both difficult and costly.</p> + +<h2><a name="why" id="why">1.3 Why the need for XHTML?</a></h2> + +<p>The benefits of migrating to XHTML 1.0 are described above. Some of the +benefits of migrating to XHTML in general are:</p> + +<ul> +<li>Document developers and user agent designers are constantly +discovering new ways to express their ideas through new markup. In XML, it is +relatively easy to introduce new elements or additional element +attributes. The XHTML family is designed to accommodate these extensions +through XHTML modules and techniques for developing new XHTML-conforming +modules (described in the forthcoming XHTML Modularization specification). +These modules will permit the combination of existing and +new feature sets when developing content and when designing new user +agents.</li> + +<li>Alternate ways of accessing the Internet are constantly being +introduced. Some estimates indicate that by the year 2002, 75% of +Internet document viewing will be carried out on these alternate +platforms. The XHTML family is designed with general user agent +interoperability in mind. Through a new user agent and document profiling +mechanism, servers, proxies, and user agents will be able to perform +best effort content transformation. Ultimately, it will be possible to +develop XHTML-conforming content that is usable by any XHTML-conforming +user agent.</li> + +</ul> +<!--OddPage--> +<h1><a name="defs" id="defs">2. Definitions</a></h1> + +<h2><a name="terms" id="terms">2.1 Terminology</a></h2> + +<p>The following terms are used in this specification. These +terms extend the definitions in <a href="#ref-rfc2119"> +[RFC2119]</a> in ways based upon similar definitions in ISO/<abbr +title="International Electro-technical Commission">IEC</abbr> +9945-1:1990 <a href="#ref-posix">[POSIX.1]</a>:</p> + +<dl> +<dt>Implementation-defined</dt> + +<dd>A value or behavior is implementation-defined when it is left +to the implementation to define [and document] the corresponding +requirements for correct document construction.</dd> + +<dt>May</dt> + +<dd>With respect to implementations, the word "may" is to be +interpreted as an optional feature that is not required in this +specification but can be provided. With respect to <a href= +"#docconf">Document Conformance</a>, the word "may" means that +the optional feature must not be used. The term "optional" has +the same definition as "may".</dd> + +<dt>Must</dt> + +<dd>In this specification, the word "must" is to be interpreted +as a mandatory requirement on the implementation or on Strictly +Conforming XHTML Documents, depending upon the context. The term +"shall" has the same definition as "must".</dd> + +<dt>Reserved</dt> + +<dd>A value or behavior is unspecified, but it is not allowed to +be used by Conforming Documents nor to be supported by a +Conforming User Agents.</dd> + +<dt>Should</dt> + +<dd>With respect to implementations, the word "should" is to be +interpreted as an implementation recommendation, but not a +requirement. With respect to documents, the word "should" is to +be interpreted as recommended programming practice for documents +and a requirement for Strictly Conforming XHTML Documents.</dd> + +<dt>Supported</dt> + +<dd>Certain facilities in this specification are optional. If a +facility is supported, it behaves as specified by this +specification.</dd> + +<dt>Unspecified</dt> + +<dd>When a value or behavior is unspecified, the specification +defines no portability requirements for a facility on an +implementation even when faced with a document that uses the +facility. A document that requires specific behavior in such an +instance, rather than tolerating any behavior when using that +facility, is not a Strictly Conforming XHTML Document.</dd> +</dl> + +<h2><a name="general" id="general">2.2 General Terms</a></h2> + +<dl> +<dt>Attribute</dt> + +<dd>An attribute is a parameter to an element declared in the +DTD. An attribute's type and value range, including a possible +default value, are defined in the DTD.</dd> + +<dt>DTD</dt> + +<dd>A DTD, or document type definition, is a collection of XML +declarations that, as a collection, defines the legal structure, +<span class="term">elements</span>, and <span class="term"> +attributes</span> that are available for use in a document that +complies to the DTD.</dd> + +<dt>Document</dt> + +<dd>A document is a stream of data that, after being combined +with any other streams it references, is structured such that it +holds information contained within <span class="term"> +elements</span> that are organized as defined in the associated +<span class="term">DTD</span>. See <a href="#docconf">Document +Conformance</a> for more information.</dd> + +<dt>Element</dt> + +<dd>An element is a document structuring unit declared in the +<span class="term">DTD</span>. The element's content model is +defined in the <span class="term">DTD</span>, and additional +semantics may be defined in the prose description of the +element.</dd> + +<dt><a name="facilities" id="facilities">Facilities</a></dt> + +<dd>Functionality includes <span class="term">elements</span>, +<span class="term">attributes</span>, and the semantics +associated with those <span class="term">elements</span> and +<span class="term">attributes</span>. An implementation +supporting that functionality is said to provide the necessary +facilities.</dd> + +<dt>Implementation</dt> + +<dd>An implementation is a system that provides collection of +<span class="term">facilities</span> and services that supports +this specification. See <a href="#uaconf">User Agent +Conformance</a> for more information.</dd> + +<dt>Parsing</dt> + +<dd>Parsing is the act whereby a <span class="term"> +document</span> is scanned, and the information contained within +the <span class="term">document</span> is filtered into the +context of the <span class="term">elements</span> in which the +information is structured.</dd> + +<dt>Rendering</dt> + +<dd>Rendering is the act whereby the information in a <span +class="term">document</span> is presented. This presentation is +done in the form most appropriate to the environment (e.g. +aurally, visually, in print).</dd> + +<dt>User Agent</dt> + +<dd>A user agent is an <span class="term">implementation</span> +that retrieves and processes XHTML documents. See <a href= +"#uaconf">User Agent Conformance</a> for more information.</dd> + +<dt>Validation</dt> + +<dd>Validation is a process whereby <span class="term"> +documents</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"> +attributes</span> are consistent with the definitions in the +<span class="term">DTD</span>.</dd> + +<dt><a name="wellformed" id="wellformed">Well-formed</a></dt> + +<dd>A <span class="term">document</span> is well-formed when it +is structured according to the rules defined in <a href= +"http://www.w3.org/TR/REC-xml#sec-well-formed">Section 2.1</a> of +the XML 1.0 Recommendation <a href="#ref-xml">[XML]</a>. +Basically, this definition states that elements, delimited by +their start and end tags, are nested properly within one +another.</dd> +</dl> + +<!--OddPage--> +<h1><a name="normative" id="normative">3. Normative Definition of +XHTML 1.0</a></h1> + +<h2><a name="docconf" id="docconf">3.1 Document +Conformance</a></h2> + +<p>This version of XHTML provides a definition of strictly +conforming XHTML documents, which are restricted to tags and +attributes from the XHTML namespace. See <a href= +"#well-formed">Section 3.1.2</a> for information on using XHTML +with other namespaces, for instance, to include metadata +expressed in <abbr title="Resource Description Format">RDF</abbr> within XHTML documents.</p> + +<h3><a name="strict" id="strict">3.1.1 Strictly Conforming +Documents</a></h3> + +<p>A Strictly Conforming XHTML Document is a document that +requires only the facilities described as mandatory in this +specification. Such a document must meet all of the following +criteria:</p> + +<ol> +<li> +<p>It must validate against one of the three DTDs found in <a +href="#dtds">Appendix A</a>.</p> +</li> + +<li> +<p>The root element of the document must be <code> +<html></code>.</p> +</li> + +<li> +<p>The root element of the document must designate the XHTML +namespace using the <code>xmlns</code> attribute <a href= +"#ref-xmlns">[XMLNAMES]</a>. The namespace for XHTML is +defined to be +<code>http://www.w3.org/1999/xhtml</code>.</p> +</li> + +<li> +<p>There must be a DOCTYPE declaration in the document prior to +the root element. The public identifier included in +the DOCTYPE declaration must reference one of the three DTDs +found in <a href="#dtds">Appendix A</a> using the respective +Formal Public Identifier. The system identifier may be changed to reflect +local system conventions.</p> + +<pre> +<!DOCTYPE html + PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/1999/PR-xhtml1-19991210/DTD/xhtml1-strict.dtd> + +<!DOCTYPE html + PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/1999/PR-xhtml1-19991210/DTD/xhtml1-transitional.dtd> + +<!DOCTYPE html + PUBLIC "-//W3C//DTD XHTML 1.0 Frameset//EN" + "http://www.w3.org/TR/1999/PR-xhtml1-19991210/DTD/xhtml1-frameset.dtd> +</pre> +</li> +</ol> + +<p>Here is an example of a minimal XHTML document.</p> + +<div class="good"> +<pre> +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE html + PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/1999/PR-xhtml1-19991210/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> + <head> + <title>Virtual Library</title> + </head> + <body> + <p>Moved to <a href="http://vlib.org/">vlib.org</a>.</p> + </body> +</html></pre> +</div> + +<p>Note that in this example, the XML declaration is included. An XML +declaration like the one above is +not required in all XML documents. XHTML document authors are strongly encouraged to use XML declarations in all their documents. Such a declaration is required +when the character encoding of the document is other than the default UTF-8 or +UTF-16.</p> + +<h3><a name="well-formed" id="well-formed">3.1.2 Using XHTML with +other namespaces</a></h3> + +<p>The XHTML namespace may be used with other XML namespaces +as per <a href="#ref-xmlns">[XMLNAMES]</a>, although such +documents are not strictly conforming XHTML 1.0 documents as +defined above. Future work by W3C will address ways to specify +conformance for documents involving multiple namespaces.</p> + +<p>The following example shows the way in which XHTML 1.0 could +be used in conjunction with the MathML Recommendation:</p> + +<div class="good"> +<pre> +<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> + <head> + <title>A Math Example</title> + </head> + <body> + <p>The following is MathML markup:</p> + <math xmlns="http://www.w3.org/1998/Math/MathML"> + <apply> <log/> + <logbase> + <cn> 3 </cn> + </logbase> + <ci> x </ci> + </apply> + </math> + </body> +</html> +</pre> +</div> + +<p>The following example shows the way in which XHTML 1.0 markup +could be incorporated into another XML namespace:</p> + +<div class="good"> +<pre> +<?xml version="1.0" encoding="UTF-8"?> +<!-- initially, the default namespace is "books" --> +<book xmlns='urn:loc.gov:books' + xmlns:isbn='urn:ISBN:0-395-36341-6' xml:lang="en" lang="en"> + <title>Cheaper by the Dozen</title> + <isbn:number>1568491379</isbn:number> + <notes> + <!-- make HTML the default namespace for a hypertext commentary --> + <p xmlns='http://www.w3.org/1999/xhtml'> + This is also available <a href="http://www.w3.org/">online</a>. + </p> + </notes> +</book> +</pre> +</div> + +<h2><a name="uaconf" id="uaconf">3.2 User Agent +Conformance</a></h2> + +<p>A conforming user agent must meet all of the following +criteria:</p> + +<ol> +<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 +an XHTML document for well-formedness. If the user agent claims +to be a validating user agent, it must also validate documents +against their referenced DTDs according to <a href="#ref-xml"> +[XML]</a>.</li> + +<li>When the user agent claims to support <a href="#facilities"> +facilities</a> defined within this specification or required by +this specification through normative reference, it must do so in +ways consistent with the facilities' definition.</li> + +<li>When a user agent processes an XHTML document as generic XML, +it shall only recognize attributes of type +<code>ID</code> (e.g. the <code>id</code> attribute on most XHTML elements) +as fragment identifiers.</li> + +<li>If a user agent encounters an element it does not recognize, +it must render the element's content.</li> + +<li>If a user agent encounters an attribute it does not +recognize, it must ignore the entire attribute specification +(i.e., the attribute and its value).</li> + +<li>If a user agent encounters an attribute value it doesn't +recognize, it must use the default attribute value.</li> + +<li>If it encounters an entity reference (other than one +of the predefined entities) for which the User Agent has +processed no declaration (which could happen if the declaration +is in the external subset which the User Agent hasn't read), the entity +reference should be rendered as the characters (starting +with the ampersand and ending with the semi-colon) that +make up the entity reference.</li> + +<li>When rendering content, User Agents that encounter +characters 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> + +<li> +The following characters are defined in [XML] as whitespace characters: + +<ul> +<li>Space (&#x0020;)</li> +<li>Tab (&#x0009;)</li> +<li>Carriage return (&#x000D;)</li> +<li>Line feed (&#x000A;)</li> +</ul> + +<p> +The XML processor normalizes different system's line end codes into one +single line-feed character, that is passed up to the application. The XHTML +user agent in addition, must treat the following characters as whitespace: +</p> + +<ul> +<li>Form feed (&#x000C;)</li> +<li>Zero-width space (&#x200B;)</li> +</ul> + +<p> +In elements where the 'xml:space' attribute is set to 'preserve', the user +agent must leave all whitespace characters intact (with the exception of +leading and trailing whitespace characters, which should be removed). +Otherwise, whitespace +is handled according to the following rules: +</p> + +<ul> +<li> +All whitespace surrounding block elements should be removed. +</li> +<li> +Comments are removed entirely and do not affect whitespace handling. One +whitespace character on either side of a comment is treated as two white +space characters. +</li> +<li> +Leading and trailing whitespace inside a block element must be removed. +</li> +<li>Line feed characters within a block element must be converted into a +space (except when the 'xml:space' attribute is set to 'preserve'). +</li> +<li> +A sequence of white space characters must be reduced to a single space +character (except when the 'xml:space' attribute is set to 'preserve'). +</li> +<li> +With regard to rendition, +the User Agent should render the content in a +manner appropriate to the language in which the content is written. +In languages whose primary script is Latinate, the ASCII space +character is typically used to encode both grammatical word boundaries and +typographic whitespace; in languages whose script is related to Nagari +(e.g., Sanskrit, Thai, etc.), grammatical boundaries may be encoded using +the ZW 'space' character, but will not typically be represented by +typographic whitespace in rendered output; languages using Arabiform scripts +may encode typographic whitespace using a space character, but may also use +the ZW space character to delimit 'internal' grammatical boundaries (what +look like words in Arabic to an English eye frequently encode several words, +e.g. 'kitAbuhum' = 'kitAbu-hum' = 'book them' == their book); and languages +in the Chinese script tradition typically neither encode such delimiters nor +use typographic whitespace in this way. +</li> +</ul> + +<p>Whitespace in attribute values is processed according to <a +href="#ref-xml">[XML]</a>.</p> +</li> +</ol> + +<!--OddPage--> +<h1><a name="diffs" id="diffs">4. Differences with HTML +4.0</a></h1> + +<p>Due to the fact that XHTML is an XML application, certain +practices that were perfectly legal in SGML-based HTML 4.0 <a +href="#ref-html4">[HTML]</a> must be changed.</p> + +<h2><a name="h-4.1" id="h-4.1">4.1 Documents must be +well-formed</a></h2> + +<p><a href="#wellformed">Well-formedness</a> is a new concept +introduced by <a href="#ref-xml">[XML]</a>. Essentially this +means that all elements must either have closing tags or be +written in a special form (as described below), and that all the +elements must nest.</p> + +<p>Although overlapping is illegal in SGML, it was widely +tolerated in existing browsers.</p> + +<div class="good"> +<p><strong><em>CORRECT: nested elements.</em></strong></p> + +<p><p>here is an emphasized +<em>paragraph</em>.</p></p> +</div> + +<div class="bad"> +<p><strong><em>INCORRECT: overlapping elements</em></strong></p> + +<p><p>here is an emphasized +<em>paragraph.</p></em></p> +</div> + +<h2><a name="h-4.2" id="h-4.2">4.2 Element and attribute +names must be in lower case</a></h2> + +<p>XHTML documents must use lower case for all HTML element and +attribute names. This difference is necessary because XML is +case-sensitive e.g. <li> and <LI> are different +tags.</p> + +<h2><a name="h-4.3" id="h-4.3">4.3 For non-empty elements, +end tags are required</a></h2> + +<p>In SGML-based HTML 4.0 certain elements were permitted to omit +the end tag; with the elements that followed implying closure. +This omission is not permitted in XML-based XHTML. All elements +other than those declared in the DTD as <code>EMPTY</code> must +have an end tag.</p> + +<div class="good"> +<p><strong><em>CORRECT: terminated elements</em></strong></p> + +<p><p>here is a paragraph.</p><p>here is +another paragraph.</p></p> +</div> + +<div class="bad"> +<p><strong><em>INCORRECT: unterminated elements</em></strong></p> + +<p><p>here is a paragraph.<p>here is another +paragraph.</p> +</div> + +<h2><a name="h-4.4" id="h-4.4">4.4 Attribute values must +always be quoted</a></h2> + +<p>All attribute values must be quoted, even those which appear +to be numeric.</p> + +<div class="good"> +<p><strong><em>CORRECT: quoted attribute values</em></strong></p> + +<p><table rows="3"></p> +</div> + +<div class="bad"> +<p><strong><em>INCORRECT: unquoted attribute values</em></strong></p> + +<p><table rows=3></p> +</div> + +<h2><a name="h-4.5" id="h-4.5">4.5 Attribute +Minimization</a></h2> + +<p>XML does not support attribute minimization. Attribute-value +pairs must be written in full. Attribute names such as <code> +compact</code> and <code>checked</code> cannot occur in elements +without their value being specified.</p> + +<div class="good"> +<p><strong><em>CORRECT: unminimized attributes</em></strong></p> + +<p><dl compact="compact"></p> +</div> + +<div class="bad"> +<p><strong><em>INCORRECT: minimized attributes</em></strong></p> + +<p><dl compact></p> +</div> + +<h2><a name="h-4.6" id="h-4.6">4.6 Empty Elements</a></h2> + +<p>Empty elements must either have an end tag or the start tag must end with <code>/></code>. For instance, +<code><br/></code> or <code><hr></hr></code>. See <a +href="#guidelines">HTML Compatibility Guidelines</a> for information on ways to +ensure this is backward compatible with HTML 4.0 user agents.</p> + +<div class="good"> +<p><strong><em>CORRECT: terminated empty tags</em></strong></p> + +<p><br/><hr/></p> +</div> + +<div class="bad"> +<p><strong><em>INCORRECT: unterminated empty tags</em></strong></p> + +<p><br><hr></p> +</div> + +<h2><a name="h-4.7" id="h-4.7">4.7 Whitespace handling in +attribute values</a></h2> + +<p>In attribute values, user agents will strip leading and +trailing whitespace from attribute values and map sequences +of one or more whitespace characters (including line breaks) to +a single inter-word space (an ASCII space character for western +scripts). See <a href="http://www.w3.org/TR/REC-xml#AVNormalize"> +Section 3.3.3</a> of <a href="#ref-xml">[XML]</a>.</p> + +<h2><a name="h-4.8" id="h-4.8">4.8 Script and Style +elements</a></h2> + +<p>In XHTML, the script and style elements are declared as having +<code>#PCDATA</code> content. As a result, <code><</code> and +<code>&</code> will be treated as the start of markup, and +entities such as <code>&lt;</code> and <code>&amp;</code> +will be recognized as entity references by the XML processor to +<code><</code> and <code>&</code> respectively. Wrapping +the content of the script or style element within a <code> +CDATA</code> marked section avoids the expansion of these +entities.</p> + +<div class="good"> +<pre> +<script> + <![CDATA[ + ... unescaped script content ... + ]]> + </script> +</pre> +</div> + +<p><code>CDATA</code> sections are recognized by the XML +processor and appear as nodes in the Document Object Model, see +<a href= +"http://www.w3.org/TR/REC-DOM-Level-1/level-one-core.html#ID-E067D597"> +Section 1.3</a> of the DOM Level 1 Recommendation <a href= +"#ref-dom">[DOM]</a>.</p> + +<p>An alternative is to use external script and style +documents.</p> + +<h2><a name="h-4.9" id="h-4.9">4.9 SGML exclusions</a></h2> + +<p>SGML gives the writer of a DTD the ability to exclude specific +elements from being contained within an element. Such +prohibitions (called "exclusions") are not possible in XML.</p> + +<p>For example, the HTML 4.0 Strict DTD forbids the nesting of an +'<code>a</code>' element within another '<code>a</code>' element +to any descendant depth. It is not possible to spell out such +prohibitions in XML. Even though these prohibitions cannot be +defined in the DTD, certain elements should not be nested. A +summary of such elements and the elements that should not be +nested in them is found in the normative <a href="#prohibitions"> +Appendix B</a>.</p> + +<h2><a name="h-4.10" id="h-4.10">4.10 The elements with 'id' and 'name' +attributes</a></h2> + +<p>HTML 4.0 defined the <code>name</code> attribute for the elements +<code>a</code>, +<code>applet</code>, <code>frame</code>, +<code>iframe</code>, <code>img</code>, and <code>map</code>. +HTML 4.0 also introduced +the <code>id</code> attribute. Both of these attributes are designed to be +used as fragment identifiers.</p> +<p>In XML, fragment identifiers are of type <code>ID</code>, and +there can only be a single attribute of type <code>ID</code> per element. +Therefore, in XHTML 1.0 the <code>id</code> +attribute is defined to be of type <code>ID</code>. In order to +ensure that XHTML 1.0 documents are well-structured XML documents, XHTML 1.0 +documents MUST use the <code>id</code> attribute when defining fragment +identifiers, even on elements that historically have also had a +<code>name</code> attribute. +See the <a href="#guidelines">HTML Compatibility +Guidelines</a> for information on ensuring such anchors are backwards +compatible when serving XHTML documents as media type <code>text/html</code>. +</p> +<p>Note that in XHTML 1.0, the <code>name</code> attribute of these +elements is formally deprecated, and will be removed in a +subsequent version of XHTML.</p> + +<!--OddPage--> +<h1><a name="issues" id="issues">5. Compatibility Issues</a></h1> + +<p>Although there is no requirement for XHTML 1.0 documents to be +compatible with existing user agents, in practice this is easy to +accomplish. Guidelines for creating compatible documents can be +found in <a href="#guidelines">Appendix C</a>.</p> + +<h2><a name="media" id="media">5.1 Internet Media Type</a></h2> +<p>As of the publication of this recommendation, the general +recommended MIME labeling for XML-based applications +has yet to be resolved.</p> + +<p>However, XHTML Documents which follow the guidelines set forth +in <a href="#guidelines">Appendix C</a>, "HTML Compatibility Guidelines" may be +labeled with the Internet Media Type "text/html", as they +are compatible with most HTML browsers. This document +makes no recommendation about MIME labeling of other +XHTML documents.</p> + +<!--OddPage--> +<h1><a name="future" id="future">6. Future Directions</a></h1> + +<p>XHTML 1.0 provides the basis for a family of document types +that will extend and subset XHTML, in order to support a wide +range of new devices and applications, by defining modules and +specifying a mechanism for combining these modules. This +mechanism will enable the extension and sub-setting of XHTML 1.0 +in a uniform way through the definition of new modules.</p> + +<h2><a name="mods" id="mods">6.1 Modularizing HTML</a></h2> + +<p>As the use of XHTML moves from the traditional desktop user +agents to other platforms, it is clear that not all of the XHTML +elements will be required on all platforms. For example a hand +held device or a cell-phone may only support a subset of XHTML +elements.</p> + +<p>The process of modularization breaks XHTML up into a series of +smaller element sets. These elements can then be recombined to +meet the needs of different communities.</p> + +<p>These modules will be defined in a later W3C document.</p> + +<h2><a name="extensions" id="extensions">6.2 Subsets and +Extensibility</a></h2> + +<p>Modularization brings with it several advantages:</p> + +<ul> +<li> +<p>It provides a formal mechanism for sub-setting XHTML.</p> +</li> + +<li> +<p>It provides a formal mechanism for extending XHTML.</p> +</li> + +<li> +<p>It simplifies the transformation between document types.</p> +</li> + +<li> +<p>It promotes the reuse of modules in new document types.</p> +</li> +</ul> + +<h2><a name="profiles" id="profiles">6.3 Document +Profiles</a></h2> + +<p>A document profile specifies the syntax and semantics of a set +of documents. Conformance to a document profile provides a basis +for interoperability guarantees. The document profile specifies +the facilities required to process documents of that type, e.g. +which image formats can be used, levels of scripting, style sheet +support, and so on.</p> + +<p>For product designers this enables various groups to define +their own standard profile.</p> + +<p>For authors this will obviate the need to write several +different versions of documents for different clients.</p> + +<p>For special groups such as chemists, medical doctors, or +mathematicians this allows a special profile to be built using +standard HTML elements plus a group of elements geared to the +specialist's needs.</p> + +<!--OddPage--> +<h1><a name="appendices" id="appendices"></a> +<a name="dtds" id="dtds">Appendix A. DTDs</a></h1> + +<p><b>This appendix is normative.</b></p> + +<p>These DTDs and entity sets form a normative part of this +specification. The complete set of DTD files together with an XML +declaration and SGML Open Catalog is included in the <a href= +"xhtml1.zip">zip file</a> for this specification.</p> + +<h2><a name="h-A1" id="h-A1">A.1 Document Type +Definitions</a></h2> + +<p>These DTDs approximate the HTML 4.0 DTDs. It is likely that +when the DTDs are modularized, a method of DTD construction will +be employed that corresponds more closely to HTML 4.0.</p> + +<ul> +<li> +<p><a href="DTD/xhtml1-strict.dtd" type="text/plain"> +XHTML-1.0-Strict</a></p> +</li> + +<li> +<p><a href="DTD/xhtml1-transitional.dtd" type="text/plain"> +XHTML-1.0-Transitional</a></p> +</li> + +<li> +<p><a href="DTD/xhtml1-frameset.dtd" type="text/plain"> +XHTML-1.0-Frameset</a></p> +</li> +</ul> + +<h2><a name="h-A2" id="h-A2">A.2 Entity Sets</a></h2> + +<p>The XHTML entity sets are the same as for HTML 4.0, but have +been modified to be valid XML 1.0 entity declarations. Note the +entity for the Euro currency sign (<code>&euro;</code> or +<code>&#8364;</code> or <code>&#x20AC;</code>) is defined +as part of the special characters.</p> + +<ul> +<li> +<p><a href="DTD/xhtml-lat1.ent">Latin-1 characters</a></p> +</li> + +<li> +<p><a href="DTD/xhtml-special.ent">Special characters</a></p> +</li> + +<li> +<p><a href="DTD/xhtml-symbol.ent">Symbols</a></p> +</li> +</ul> + +<!--OddPage--> +<h1><a name="prohibitions" id="prohibitions">Appendix B. Element +Prohibitions</a></h1> + +<p><b>This appendix is normative.</b></p> + +<p>The following elements have prohibitions on which elements +they can contain (see <a href="#h-4.9">Section 4.9</a>). This +prohibition applies to all depths of nesting, i.e. it contains +all the descendant elements.</p> + +<dl><dt><code class="tag">a</code></dt> +<dd> +cannot contain other <code>a</code> elements.</dd> +<dt><code class="tag">pre</code></dt> +<dd>cannot contain the <code>img</code>, <code>object</code>, +<code>big</code>, <code>small</code>, <code>sub</code>, or <code> +sup</code> elements.</dd> + +<dt><code class="tag">button</code></dt> +<dd>cannot contain the <code>input</code>, <code>select</code>, +<code>textarea</code>, <code>label</code>, <code>button</code>, +<code>form</code>, <code>fieldset</code>, <code>iframe</code> or +<code>isindex</code> elements.</dd> +<dt><code class="tag">label</code></dt> +<dd>cannot contain other <code class="tag">label</code> elements.</dd> +<dt><code class="tag">form</code></dt> +<dd>cannot contain other <code>form</code> elements.</dd> +</dl> + +<!--OddPage--> +<h1><a name="guidelines" id="guidelines">Appendix C. +HTML Compatibility Guidelines</a></h1> + +<p><b>This appendix is informative.</b></p> + +<p>This appendix summarizes design guidelines for authors who +wish their XHTML documents to render on existing HTML user +agents.</p> + +<h2>C.1 Processing Instructions</h2> +<p>Be aware that processing instructions are rendered on some +user agents. However, also note that when the XML declaration is not included +in a document, the document can only use the default character encodings UTF-8 +or UTF-16.</p> + +<h2>C.2 Empty Elements</h2> +<p>Include a space before the trailing <code>/</code> and <code> +></code> of empty elements, e.g. <code class="greenmono"> +<br /></code>, <code class="greenmono"> +<hr /></code> and <code class="greenmono"><img +src="karen.jpg" alt="Karen" /></code>. Also, use the +minimized tag syntax for empty elements, e.g. <code class= +"greenmono"><br /></code>, as the alternative syntax <code +class="greenmono"><br></br></code> allowed by XML +gives uncertain results in many existing user agents.</p> + +<h2>C.3 Element Minimization and Empty Element Content</h2> +<p>Given an empty instance of an element whose content model is +not <code>EMPTY</code> (for example, an empty title or paragraph) +do not use the minimized form (e.g. use <code class="greenmono"> +<p> </p></code> and not <code class="greenmono"> +<p /></code>).</p> + +<h2>C.4 Embedded Style Sheets and Scripts</h2> +<p>Use external style sheets if your style sheet uses <code> +<</code> or <code>&</code> or <code>]]></code> or <code>--</code>. Use +external scripts if your script uses <code><</code> or <code> +&</code> or <code>]]></code> or <code>--</code>. Note that XML parsers +are permitted to silently remove the contents of comments. Therefore, the historical +practice of "hiding" scripts and style sheets within comments to make the +documents backward compatible is likely to not work as expected in XML-based +implementations.</p> + +<h2>C.5 Line Breaks within Attribute Values</h2> +<p>Avoid line breaks and multiple whitespace characters within +attribute values. These are handled inconsistently by user +agents.</p> + +<h2>C.6 Isindex</h2> +<p>Don't include more than one <code>isindex</code> element in +the document <code>head</code>. The <code>isindex</code> element +is deprecated in favor of the <code>input</code> element.</p> + +<h2>C.7 The <code>lang</code> and <code>xml:lang</code> Attributes</h2> +<p>Use both the <code>lang</code> and <code>xml:lang</code> +attributes when specifying the language of an element. The value +of the <code>xml:lang</code> attribute takes precedence.</p> + +<h2>C.8 Fragment Identifiers</h2> +<p>In XML, <abbr title="Uniform Resource Identifiers">URIs</abbr> [<a href="#ref-rfc2396">RFC2396</a>] that end with fragment identifiers of the form +<code>"#foo"</code> do not refer to elements with an attribute +<code>name="foo"</code>; rather, they refer to elements with an +attribute defined to be of type <code>ID</code>, e.g., the <code> +id</code> attribute in HTML 4.0. Many existing HTML clients don't +support the use of <code>ID</code>-type attributes in this way, +so identical values may be supplied for both of these attributes to ensure +maximum forward and backward compatibility (e.g., <code class= +"greenmono"><a id="foo" name="foo">...</a></code>).</p> + +<p>Further, since the set of +legal values for attributes of type <code>ID</code> is much smaller than +for those of type <code>CDATA</code>, the type of the <code>name</code> +attribute has been changed to <code>NMTOKEN</code>. This attribute is +constrained such that it can only have the same values as type +<code>ID</code>, or as the <code>Name</code> production in XML 1.0 Section +2.5, production 5. Unfortunately, this constraint cannot be expressed in the +XHTML 1.0 DTDs. Because of this change, care must be taken when +converting existing HTML documents. The values of these attributes +must be unique within the document, valid, and any references to these +fragment identifiers (both +internal and external) must be updated should the values be changed during +conversion.</p> +<p>Finally, note that XHTML 1.0 has deprecated the +<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> +elements, and it will be +removed from XHTML in subsequent versions.</p> + +<h2>C.9 Character Encoding</h2> +<p>To specify a character encoding in the document, use both the +encoding attribute specification on the xml declaration (e.g. +<code class="greenmono"><?xml version="1.0" +encoding="EUC-JP"?></code>) and a meta http-equiv statement +(e.g. <code class="greenmono"><meta http-equiv="Content-type" +content='text/html; charset="EUC-JP"' /></code>). The +value of the encoding attribute of the xml processing instruction +takes precedence.</p> + +<h2>C.10 Boolean Attributes</h2> +<p>Some HTML user agents are unable to interpret boolean +attributes when these appear in their full (non-minimized) form, +as required by XML 1.0. Note this problem doesn't effect user +agents compliant with HTML 4.0. The following attributes are +involved: <code>compact</code>, <code>nowrap</code>, <code> +ismap</code>, <code>declare</code>, <code>noshade</code>, <code> +checked</code>, <code>disabled</code>, <code>readonly</code>, +<code>multiple</code>, <code>selected</code>, <code> +noresize</code>, <code>defer</code>.</p> + +<h2>C.11 Document Object Model and XHTML</h2> +<p> +The Document Object Model level 1 Recommendation [<a href="#ref-dom">DOM</a>] +defines document object model interfaces for XML and HTML 4.0. The HTML 4.0 +document object model specifies that HTML element and attribute names are +returned in upper-case. The XML document object model specifies that +element and attribute names are returned in the case they are specified. In +XHTML 1.0, elements and attributes are specified in lower-case. This apparent difference can be +addressed in two ways: +</p> +<ol> +<li>Applications that access XHTML documents served as Internet media type +<code>text/html</code> +via the <abbr title="Document Object Model">DOM</abbr> can use the HTML DOM, +and can rely upon element and attribute names being returned in +upper-case from those interfaces.</li> +<li>Applications that access XHTML documents served as Internet media types +<code>text/xml</code> or <code>application/xml</code> +can also use the XML DOM. Elements and attributes will be returned in lower-case. +Also, some XHTML elements may or may +not appear +in the object tree because they are optional in the content model +(e.g. the <code>tbody</code> element within +<code>table</code>). This occurs because in HTML 4.0 some elements were +permitted to be minimized such that their start and end tags are both omitted +(an SGML feature). +This is not possible in XML. Rather than require document authors to insert +extraneous elements, XHTML has made the elements optional. +Applications need to adapt to this +accordingly.</li> +</ol> + +<h2>C.12 Using Ampersands in Attribute Values</h2> +<p> +When an attribute value contains an ampersand, it must be expressed as a character +entity reference +(e.g. "<code>&amp;</code>"). For example, when the +<code>href</code> attribute +of the <code>a</code> element refers to a +CGI script that takes parameters, it must be expressed as +<code>http://my.site.dom/cgi-bin/myscript.pl?class=guest&amp;name=user</code> +rather than as +<code>http://my.site.dom/cgi-bin/myscript.pl?class=guest&name=user</code>. +</p> + +<h2>C.13 Cascading Style Sheets (CSS) and XHTML</h2> + +<p>The Cascading Style Sheets level 2 Recommendation [<a href="#ref-css2">CSS2</a>] defines style +properties which are applied to the parse tree of the HTML or XML +document. Differences in parsing will produce different visual or +aural results, depending on the selectors used. The following hints +will reduce this effect for documents which are served without +modification as both media types:</p> + +<ol> +<li> +CSS style sheets for XHTML should use lower case element and +attribute names.</li> + + +<li>In tables, the tbody element will be inferred by the parser of an +HTML user agent, but not by the parser of an XML user agent. Therefore +you should always explicitely add a tbody element if it is referred to +in a CSS selector.</li> + +<li>Within the XHTML name space, user agents are expected to +recognize the "id" attribute as an attribute of type ID. +Therefore, style sheets should be able to continue using the +shorthand "#" selector syntax even if the user agent does not read +the DTD.</li> + +<li>Within the XHTML name space, user agents are expected to +recognize the "class" attribute. Therefore, style sheets should be +able to continue using the shorthand "." selector syntax.</li> + +<li> +CSS defines different conformance rules for HTML and XML documents; +be aware that the HTML rules apply to XHTML documents delivered as +HTML and the XML rules apply to XHTML documents delivered as XML.</li> +</ol> +<!--OddPage--> +<h1><a name="acks" id="acks">Appendix D. +Acknowledgements</a></h1> + +<p><b>This appendix is informative.</b></p> + +<p>This specification was written with the participation of the +members of the W3C HTML working group:</p> + +<dl> +<dd>Steven Pemberton, CWI (HTML Working Group Chair)<br /> +Murray Altheim, Sun Microsystems<br /> +Daniel Austin, CNET: The Computer Network<br /> +Frank Boumphrey, HTML Writers Guild<br /> +John Burger, Mitre<br /> +Andrew W. Donoho, IBM<br /> +Sam Dooley, IBM<br /> +Klaus Hofrichter, GMD<br /> +Philipp Hoschka, W3C<br /> +Masayasu Ishikawa, W3C<br /> +Warner ten Kate, Philips Electronics<br /> +Peter King, Phone.com<br /> +Paula Klante, JetForm<br /> +Shin'ichi Matsui, W3C/Panasonic<br /> +Shane McCarron, Applied Testing and Technology (The Open Group through August +1999)<br /> +Ann Navarro, HTML Writers Guild<br /> +Zach Nies, Quark<br /> +Dave Raggett, W3C/HP (W3C lead for HTML)<br /> +Patrick Schmitz, Microsoft<br /> +Sebastian Schnitzenbaumer, Stack Overflow<br /> +Chris Wilson, Microsoft<br /> +Ted Wugofski, Gateway 2000<br /> +Dan Zigmond, WebTV Networks</dd> +</dl> + +<!--OddPage--> +<h1><a name="refs" id="refs">Appendix E. References</a></h1> + +<p><b>This appendix is informative.</b></p> + +<dl> + +<dt><a name="ref-css2" id="ref-css2"><b>[CSS2]</b></a></dt> + +<dd><a href="http://www.w3.org/TR/REC-CSS2">"Cascading Style Sheets, level 2 (CSS2) Specification"</a>, B. +Bos, H. W. Lie, C. Lilley, I. Jacobs, 12 May 1998.<br /> +Available at: <a href="http://www.w3.org/TR/REC-CSS2"> +http://www.w3.org/TR/REC-CSS2</a></dd> + +<dt><a name="ref-dom" id="ref-dom"><b>[DOM]</b></a></dt> + +<dd><a href="http://www.w3.org/TR/REC-DOM-Level-1">"Document Object Model (DOM) Level 1 Specification"</a>, Lauren +Wood <i>et al.</i>, 1 October 1998.<br /> +Available at: <a href="http://www.w3.org/TR/REC-DOM-Level-1"> +http://www.w3.org/TR/REC-DOM-Level-1</a></dd> + +<dt><a name="ref-html4" id="ref-html4"><b>[HTML]</b></a></dt> + +<dd><a href="http://www.w3.org/TR/1999/PR-html40-19990824">"HTML 4.01 Specification"</a>, D. Raggett, A. Le Hors, I. +Jacobs, 24 August 1999.<br /> +Available at: <a href="http://www.w3.org/TR/1999/PR-html40-19990824"> +http://www.w3.org/TR/1999/PR-html40-19990824</a></dd> + +<dt><a name="ref-posix" id="ref-posix"><b>[POSIX.1]</b></a></dt> + +<dd>"ISO/IEC 9945-1:1990 Information Technology - Portable +Operating System Interface (POSIX) - Part 1: System Application +Program Interface (API) [C Language]", Institute of Electrical +and Electronics Engineers, Inc, 1990.</dd> + +<dt><a name="ref-rfc2046" id="ref-rfc2046"><b> +[RFC2046]</b></a></dt> + +<dd><a href="http://www.ietf.org/rfc/rfc2046.txt">"RFC2046: Multipurpose Internet Mail Extensions (MIME) Part +Two: Media Types"</a>, N. Freed and N. Borenstein, November +1996.<br /> +Available at <a href="http://www.ietf.org/rfc/rfc2046.txt"> +http://www.ietf.org/rfc/rfc2046.txt</a>. Note that this RFC +obsoletes RFC1521, RFC1522, and RFC1590.</dd> + +<dt><a name="ref-rfc2119" id="ref-rfc2119"><b> +[RFC2119]</b></a></dt> + +<dd><a href="http://www.ietf.org/rfc/rfc2119.txt">"RFC2119: Key words for use in RFCs to Indicate Requirement +Levels"</a>, S. Bradner, March 1997.<br /> +Available at: <a href="http://www.ietf.org/rfc/rfc2119.txt"> +http://www.ietf.org/rfc/rfc2119.txt</a></dd> + +<dt><a name="ref-rfc2376" id="ref-rfc2376"><b> +[RFC2376]</b></a></dt> + +<dd><a href="http://www.ietf.org/rfc/rfc2376.txt">"RFC2376: XML Media Types"</a>, E. Whitehead, M. Murata, July +1998.<br /> +Available at: <a href="http://www.ietf.org/rfc/rfc2376.txt"> +http://www.ietf.org/rfc/rfc2376.txt</a></dd> + +<dt><a name="ref-rfc2396" id="ref-rfc2396"><b> +[RFC2396]</b></a></dt> + +<dd><a href="http://www.ietf.org/rfc/rfc2396.txt">"RFC2396: Uniform Resource Identifiers (URI): Generic +Syntax"</a>, T. Berners-Lee, R. Fielding, L. Masinter, August +1998.<br /> +This document updates RFC1738 and RFC1808.<br /> +Available at: <a href="http://www.ietf.org/rfc/rfc2396.txt"> +http://www.ietf.org/rfc/rfc2396.txt</a></dd> + +<dt><a name="ref-xml" id="ref-xml"><b>[XML]</b></a></dt> + +<dd><a href="http://www.w3.org/TR/REC-xml">"Extensible Markup Language (XML) 1.0 Specification"</a>, T. +Bray, J. Paoli, C. M. Sperberg-McQueen, 10 February 1998.<br /> +Available at: <a href="http://www.w3.org/TR/REC-xml"> +http://www.w3.org/TR/REC-xml</a></dd> + +<dt><a name="ref-xmlns" id="ref-xmlns"><b>[XMLNAMES]</b></a></dt> + +<dd><a href="http://www.w3.org/TR/REC-xml-names">"Namespaces in XML"</a>, T. Bray, D. Hollander, A. Layman, 14 +January 1999.<br /> +XML namespaces provide a simple method for qualifying names used +in XML documents by associating them with namespaces identified +by URI.<br /> +Available at: <a href="http://www.w3.org/TR/REC-xml-names"> +http://www.w3.org/TR/REC-xml-names</a></dd> + +</dl> +<p><a href="http://www.w3.org/WAI/WCAG1AAA-Conformance" +title="Explanation of Level Triple-A Conformance"> +<img height="32" width="88" +src="wcag1AAA.gif" +alt="Level Triple-A conformance icon, W3C-WAI Web Content Accessibility Guidelines 1.0" /></a></p> +<div class="navbar"> + <hr /> + <a href="#toc">table of contents</a> +</div> +</body> +</html> + |