- From: CVS User egraff <cvsmail@w3.org>
- Date: Thu, 03 Oct 2013 00:43:18 +0000
- To: public-html-commits@w3.org
Update of /sources/public/html5/html-xhtml-author-guide
In directory roscoe:/tmp/cvs-serv31554
Added Files:
WD-html-polyglot-20131008.htm
Log Message:
Eliot cleaned up some stuff in Robin's version
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<a href="http://www.w3.org/"><img height="48" width="72" alt="W3C" src="https://www.w3.org/Icons/w3c_home" /></a>
</p>
<h1 id="title" class="title p-name">Polyglot Markup: A robust profile of the HTML5 vocabulary</h1>
<h2 id="w3c-working-draft-08-october-2013"><abbr title="World Wide Web Consortium">W3C</abbr> Working Draft 08 October 2013</h2>
<dl>
<dt>This version:</dt>
<dd><a href="http://www.w3.org/TR/2013/WD-html-polyglot-20131008/" class="u-url">http://www.w3.org/TR/2013/WD-html-polyglot-20131008/</a></dd>
<dt>Latest published version:</dt>
<dd><a href="http://www.w3.org/TR/html-polyglot/">http://www.w3.org/TR/html-polyglot/</a></dd>
<dt>Latest editor's draft:</dt>
<dd><a href="http://dev.w3.org/html5/html-xhtml-author-guide/html-xhtml-authoring-guide.html">http://dev.w3.org/html5/html-xhtml-author-guide/html-xhtml-authoring-guide.html</a></dd>
<dt>Previous version:</dt>
<dd><a href="http://www.w3.org/TR/2012/WD-html-polyglot-20121025/" rel="dcterms:replaces">http://www.w3.org/TR/2012/WD-html-polyglot-20121025/</a></dd>
<dt>Editors:</dt>
<dd class="p-author h-card vcard"><span><span class="p-name fn">Eliot Graff</span>, Microsoft Corporation</span>
</dd>
<dd class="p-author h-card vcard"><span><span class="p-name fn">Leif H. Silli</span>, &METODIUS DA</span>
</dd>
</dl>
<p class="copyright">
<a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> ©
2013
<a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup>
(<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>,
<a href="http://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>,
<a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</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> and
<a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.
</p>
<hr />
</div>
<section class="introductory"><h2 aria-level="1" role="heading" id="h2_abstract">Abstract</h2><p>
A document that uses <a title="polyglot markup" href="#dfn-polyglot-markup" class="internalDFN">polyglot markup</a> is a document that is a stream of bytes that parses into identical document trees
(with some exceptions, as noted in the <a href="#introduction">Introduction</a>) when processed as HTML and when processed as XML.
Polyglot markup that meets a well-defined set of constraints is interpreted as compatible, regardless of whether they are processed as HTML or as XHTML, per the HTML5 specification.
Polyglot markup uses a specific DOCTYPE, namespace declarations, and a specific case—normally lower case but occasionally camel case—for element and attribute names.
Polyglot markup uses lower case for certain attribute values.
Further constraints include those on void elements, named entity references, and the use of scripts and style.
<!--End section: Abstract-->
</p></section><section class="introductory" id="sotd" typeof="bibo:Chapter" resource="#sotd" rel="bibo:chapter"><h2 aria-level="1" role="heading" id="h2_sotd">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. A list of current <abbr title="World Wide Web Consortium">W3C</abbr> publications and the latest revision
of this technical report can be found in the <a href="http://www.w3.org/TR/"><abbr title="World Wide Web Consortium">W3C</abbr> technical reports
index</a> at http://www.w3.org/TR/.</em>
</p>
<p>
This document summarizes design guidelines for authors who wish their XHTML or HTML documents to validate on both HTML and XML parsers.
This specification is intended to be used by web authors, particularly authors who want to serve receivers which may have either (but not both) XML or HTML parsers available.
This commonly arises in legacy systems and content syndication.
Polyglot is one of several transition mechanisms from legacy XML to HTML5 and this document serves to describe it accurately.
</p>
<p>
No recommendation is made in this document or by the <abbr title="World Wide Web Consortium">W3C</abbr> regarding whether or not to publish polyglot content.
In general, authors are encouraged to publish HTML content using HTML5 syntax and media types
(either HTML syntax and <code>text/html</code>, or XHTML syntax and <code>application/xhtml+xml</code>).
</p>
<p>
This document is not a specification for user agents and creates no obligations on user agents.
Note that this recommendation does not define how HTML5-conforming user agents should process HTML documents.
Nor does it define the meaning of the Internet Media Type <code>text/html</code>.
For user agent guidance and for these definitions, see [<cite><a class="bibref" href="#bib-HTML5">HTML5</a></cite>] and [<cite><a class="bibref" href="#bib-RFC2854">RFC2854</a></cite>].
</p>
<p>
Please submit bugs for this document by using the <abbr title="World Wide Web Consortium">W3C</abbr>'s public bug database (<a href="http://www.w3.org/Bugs/Public/">
http://www.w3.org/Bugs/Public/</a>) with the product set to <kbd>HTML WG</kbd> and the component set to
<kbd>HTML/XHTML Compatibility Authoring Guide (ed: Eliot Graff)</kbd>.
If you cannot access the bug database, submit comments by email to the mailing list noted below.
</p>
<!--End section: Status of This Document-->
<p>
This document was published by the <a href="http://www.w3.org/html/wg/">HTML working group</a> as a Working Draft.
This document is intended to become a <abbr title="World Wide Web Consortium">W3C</abbr> Recommendation.
If you wish to make comments regarding this document, please send them to
<a href="mailto:public-html@w3.org">public-html@w3.org</a>
(<a href="mailto:public-html-request@w3.org?subject=subscribe">subscribe</a>,
<a href="http://lists.w3.org/Archives/Public/public-html/">archives</a>).
All comments are welcome.</p>
<p>
Publication as a Working Draft does not imply endorsement by the <abbr title="World Wide Web Consortium">W3C</abbr> Membership.
This is a draft document and may be updated, replaced or obsoleted by other documents at
any time. It is inappropriate to cite this document as other than work in progress.
</p>
<p>
This document was produced by a group operating under the
<a href="http://www.w3.org/Consortium/Patent-Policy-20040205/" rel="w3p:patentRules" id="sotd_patent">5 February 2004 <abbr title="World Wide Web Consortium">W3C</abbr> Patent Policy</a>.
<abbr title="World Wide Web Consortium">W3C</abbr> maintains a <a rel="disclosure" href="http://www.w3.org/2004/01/pp-impl/40318/status">public list of any patent disclosures</a>
made in connection with the deliverables of the group; that page also includes instructions for
disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains
<a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential Claim(s)</a> must disclose the
information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
6 of the <abbr title="World Wide Web Consortium">W3C</abbr> Patent Policy</a>.
</p>
</section><section id="toc"><h2 class="introductory" aria-level="1" role="heading" id="h2_toc">Table of Contents</h2><ul class="toc" role="directory" id="respecContents"><li class="tocline"><a href="#introduction" class="tocxref"><span class="secno">1. </span>Introduction</a><ul class="toc"><li class="tocline"><a href="#scope" class="tocxref"><span class="secno">1.1 </span>Scope</a></li><li class="tocline"><a href="#robust" class="tocxref"><span class="secno">1.2 </span>Robustness</a></li></ul></li><li class="tocline"><a href="#syntax" class="tocxref"><span class="secno">2. </span>Syntax</a><ul class="toc"><li class="tocline"><a href="#principles" class="tocxref"><span class="secno">2.1 </span>Principles</a></li></ul></li><li class="tocline"><a href="#writing" class="tocxref"><span class="secno">3. </span>Writing HTML documents</a><ul class="toc"><li class="tocline"><a href="#PI-and-xml" class="tocxref"><span class="secno">3.1 </span>Processing instructions and the XML declaration</a></li><li class="tocline><a href="#character-encoding" class="tocxref"><span class="secno">3.2 </span>Specifying a document's character encoding</a></li><li class="tocline"><a href="#doctype" class="tocxref"><span class="secno">3.3 </span>The DOCTYPE</a></li><li class="tocline"><a href="#namespaces" class="tocxref"><span class="secno">3.4 </span>Namespaces</a><ul class="toc"><li class="tocline"><a href="#element-level-namespaces" class="tocxref"><span class="secno">3.4.1 </span>Element-level namespaces</a></li><li class="tocline"><a href="#attribute-level-namespaces" class="tocxref"><span class="secno">3.4.2 </span>Attribute-level namespaces</a></li></ul></li><li class="tocline"><a href="#elements" class="tocxref"><span class="secno">3.5 </span>Element syntax</a><ul class="toc"><li class="tocline"><a href="#required-elements" class="tocxref"><span class="secno">3.5.1 </span>Required elements and tags</a><ul class="toc"><li class="tocline"><a href="#minimal-polyglot-html-document" class="tocxref"><span class="secno">3.5.1.1 </span> minimal HTML document</a></li><li class="tocline"><a href="#required-tags-exampls" class="tocxref"><span class="secno">3.5.1.2 </span>Required tags examples</a></li></ul></li><li class="tocline"><a href="#excluded-elements" class="tocxref"><span class="secno">3.5.2 </span>Excluded elements and tags</a></li><li class="tocline"><a href="#case-sensitivity" class="tocxref"><span class="secno">3.5.3 </span>Case-sensitivity</a><ul class="toc"><li class="tocline"><a href="#element-names" class="tocxref"><span class="secno">3.5.3.1 </span>Element names</a></li><li class="tocline"><a href="#attribute-names" class="tocxref"><span class="secno">3.5.3.2 </span>Attribute names</a></li><li class="tocline"><a href="#attribute-values" class="tocxref"><span class="secno">3.5.3.3 </span>Attribute values</a></li></ul></li></ul></li><li class="tocline"><a href="#contents-of-elements" class="tocxref"><span class="secno">3.6 </span>Element contents</a><ul class="toc"><li class="tocline"><a href="#empty-elements" class="tocxref"<span class="secno">3.6.1 </span>Void elements</a></li><li class="tocline"><a href="#raw-text-elements" class="tocxref"><span class="secno">3.6.2 </span>Raw text elements (<code>script</code> and <code>style</code>)</a><ul class="toc"><li class="tocline"><a href="#safe-content" class="tocxref"><span class="secno">3.6.2.1 </span>The safe text content option</a></li><li class="tocline"><a href="#safe-CDATA-content" class="tocxref"><span class="secno">3.6.2.2 </span>The safe CDATA option</a><ul class="toc"><li class="tocline"><a href="#CDATA-rules-raw-text" class="tocxref"><span class="secno">3.6.2.2.1 </span>Safe CDATA usage rules</a></li></ul></li></ul></li><li class="tocline"><a href="#escaped-raw-text-elements" class="tocxref"><span class="secno">3.6.3 </span>Escapable raw text elements</a></li><li class="tocline"><a href="#foreign-elements" class="tocxref"><span class="secno">3.6.4 </span>Foreign elements</a></li><li class="tocline"><a href="#normal-elements" class="tocxref"><span class="secno">3.6.5 </spn>Normal elements</a></li></ul></li><li class="tocline"><a href="#text" class="tocxref"><span class="secno">3.7 </span>Text</a><ul class="toc"><li class="tocline"><a href="#newlines-in-textarea-and-pre" class="tocxref"><span class="secno">3.7.1 </span>Newlines in <code>textarea</code> and <code>pre</code> elements</a></li></ul></li><li class="tocline"><a href="#attributes" class="tocxref"><span class="secno">3.8 </span>Attributes</a><ul class="toc"><li class="tocline"><a href="#disallowed-attributes" class="tocxref"><span class="secno">3.8.1 </span>Disallowed attributes</a></li><li class="tocline"><a href="#language-attributes" class="tocxref"><span class="secno">3.8.2 </span>Language attributes</a></li><li class="tocline"><a href="#attributes-with-special-considerations" class="tocxref"><span class="secno">3.8.3 </span>Attributes with special considerations</a><ul class="toc"><li class="tocline"><a href="#id-attribute" class="tocxref"><span class="secno">3.8.3.1 </span>The <code>id</code> attribute</a></li</ul></li></ul></li><li class="tocline"><a href="#named-entity-references" class="tocxref"><span class="secno">3.9 </span>Named entity references</a></li><li class="tocline"><a href="#comments" class="tocxref"><span class="secno">3.10 </span>Comments</a></li><li class="tocline"><a href="#scripting-and-styling-polyglot-markup" class="tocxref"><span class="secno">3.11 </span>Scripting and styling <span class="formerLink">polyglot markup</span></a><ul class="toc"><li class="tocline"><a href="#javascript-and-document.write" class="tocxref"><span class="secno">3.11.1 </span>JavaScript: <code>innerHTML</code> vs <code>document.write()</code> </a></li><li class="tocline"><a href="#css-and-namespaced-attributes" class="tocxref"><span class="secno">3.11.2 </span>CSS: Attribute selectors that require a namespace prefix</a></li></ul></li><li class="tocline"><a href="#templating-restrictions" class="tocxref"><span class="secno">3.12 </span>Templating restrictions</a></li></ul></li><li class="tocline"><a href="#example-ocument" class="tocxref"><span class="secno">4. </span>Example document</a></li><li class="tocline"><a href="#acknowledgements" class="tocxref"><span class="secno">A. </span>Acknowledgements</a></li><li class="tocline"><a href="#references" class="tocxref"><span class="secno">B. </span>References</a><ul class="toc"><li class="tocline"><a href="#normative-references" class="tocxref"><span class="secno">B.1 </span>Normative references</a></li></ul></li></ul></section>
<!-- note: for principle section
In <a>polyglot markup</a>, the strings that XML and HTML interpret differently are considered <dfn>ambiguous
strings</dfn> and MUST NOT be used except when they are explicitly permitted
(such as for the ambigous namespace prefix <code>xml:</code>, which is permitted as prefix for the <code>lang</code> in the XML namespace — <code>xml:lang</code>).
-->
<section class="informative" id="introduction" typeof="bibo:Chapter" resource="#introduction" rel="bibo:chapter">
<!--OddPage-->
<h2 aria-level="1" role="heading" id="h2_introduction"><span class="secno">1. </span>Introduction</h2><p><em>This section is non-normative.</em></p>
<p>It is sometimes valuable to be able to serve HTML5 documents that are also well formed XML documents.
An author may, for example, use XML tools to generate a document, and they and others may process the document using XML tools.
The language used to create documents that can be parsed by both HTML and XML parsers is called <a title="polyglot markkup">polyglot markup</a>.
<a title="polyglot markup" href="#dfn-polyglot-markup" class="internalDFN">Polyglot markup</a> is the overlap language of documents that are both HTML5 documents and XML documents.
It is recommended that these documents be served as either <code>text/html</code> (if the content is transmitted to an HTML-aware user agent)
or <code>application/xhtml+xml</code> (if the content is transmitted to an XHTML-aware user agent).
Other permissible MIME types are <code>text/xml</code>, <code>application/xml</code>,
and any MIME type whose subtype ends with the four characters "<code>+xml</code>". [<cite><a class="bibref" href="#bib-XML-MT">XML-MT</a></cite>]</p>
<!--end general-->
<section id="scope" typeof="bibo:Chapter" resource="#scope" rel="bibo:chapter">
<h3 aria-level="2" role="heading" id="h3_scope"><span class="secno">1.1 </span>Scope</h3><p><em>This section is non-normative.</em></p>
<p>Polylglot markup is a <em><a title="robustness" href="#dfn-robustness" class="internalDFN">robust</a></em> — but entirely <em>optional</em> — profile of the HTML vocabulary.
All web content need not be authored in <a href="#dfn-polyglot-markup" class="internalDFN">polyglot markup</a> and it is primarily an option
for authors wanting to increase the <a title="robustness" href="#dfn-robustness" class="internalDFN">robustness</a> of their documents.
<a title="polyglot markup" href="#dfn-polyglot-markup" class="internalDFN">Polyglot markup</a> works best, and can be a beneficial option, in controlled environments and for authoring tools.</p>
<p><a title="polyglot markup" href="#dfn-polyglot-markup" class="internalDFN">Polyglot markup</a> is ideal for publishing when there's a strong desire to serve both HTML and XML tool chains
without simultaneously having to maintain dual copies of the content: one in HTML and a second in XHTML.
In addition, a single <a href="#dfn-polyglot-markup" class="internalDFN">polyglot markup</a> output requires less infrastructure to produce than to produce both HTML and XHTML output for the same content.
<a title="polyglot markup" href="#dfn-polyglot-markup" class="internalDFN">Polyglot markup</a> is also be beneficial when lightweight processes"”such as
quick testing or even hand-authoring"”are applied to content intended to be published both as HTML and XHTML,
especially if that content is not sent through a tool chain.</p>
<div class="note"><div class="note-title" aria-level="3" role="heading" id="h_note_1"><span>Note</span></div><p class="">XML-based HTML tools or systems intended for the most general contexts of use cannot <strong><em>depend</em></strong> on polyglot input: for maximum flexibility,
such tools should use the technique of using an HTML parser that produces an XML-compatible DOM or event stream.</p></div>
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Received on Thursday, 3 October 2013 00:43:20 UTC