iana.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en-US-x-Hixie" ><head><title>12 IANA considerations — HTML5 </title><style type="text/css">
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ul.domTree .t10 code { color: teal; }
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fieldset p { margin: 0.5em 0; }
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position: fixed;
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left: 0; right: 0;
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.stability :link, .stability :visited,
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background: transparent;
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requirements"><link href="http://www.w3.org/StyleSheets/TR/W3C-WD" rel="stylesheet" type="text/css"><style type="text/css">
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#named-character-references-table > table > tbody > tr#entity-CounterClockwiseContourIntegral > td:first-child { font-size: 0.5em; }
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font-style: italic;
font-weight: bold;
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<p class="stability" id="wip"><strong>This is a work in
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including important bug fixes, please look at the <a href="http://dev.w3.org/html5/spec/Overview.html">editor's draft</a> instead.
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<h1>HTML5</h1>
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<a href="obsolete.html" class="prev">11 Obsolete features</a> –
<a href="spec.html#contents">Table of contents</a> –
<a href="index.html" class="next">Index</a>
<ol class="toc"><li><a href="iana.html#iana"><span class="secno">12 </span>IANA considerations</a>
<ol><li><a href="iana.html#text-html"><span class="secno">12.1 </span><code>text/html</code></a></li><li><a href="iana.html#text-html-sandboxed"><span class="secno">12.2 </span><code>text/html-sandboxed</code></a></li><li><a href="iana.html#application-xhtml-xml"><span class="secno">12.3 </span><code>application/xhtml+xml</code></a></li><li><a href="iana.html#text-cache-manifest"><span class="secno">12.4 </span><code>text/cache-manifest</code></a></li></ol></li></ol></div>
<h2 id="iana"><span class="secno">12 </span>IANA considerations</h2><h3 id="text-html"><span class="secno">12.1 </span><dfn><code>text/html</code></dfn></h3><p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p><dl><dt>Type name:</dt>
<dd>text</dd>
<dt>Subtype name:</dt>
<dd>html</dd>
<dt>Required parameters:</dt>
<dd>No required parameters</dd>
<dt>Optional parameters:</dt>
<dd>
<dl><dt><code title="">charset</code></dt>
<dd>
<p>The <code title="">charset</code> parameter may be provided
to definitively specify the <a href="dom.html#document-s-character-encoding">document's character
encoding</a>, overriding any <a href="semantics.html#character-encoding-declaration" title="character encoding
declaration">character encoding declarations</a> in the
document. The parameter's value must be the name of the
character encoding used to serialize the file, must be a valid
character encoding name, and must be an <a href="infrastructure.html#ascii-case-insensitive">ASCII
case-insensitive</a> match for the <a href="infrastructure.html#preferred-mime-name">preferred MIME
name</a> for that encoding. <a href="references.html#refsIANACHARSET">[IANACHARSET]</a></p>
</dd>
</dl></dd>
<dt>Encoding considerations:</dt>
<dd>See the section on <a href="semantics.html#character-encoding-declaration" title="character encoding
declaration">character encoding declarations</a>.</dd>
<dt>Security considerations:</dt>
<dd>
<p>Entire novels have been written about the security
considerations that apply to HTML documents. Many are listed in
this document, to which the reader is referred for more
details. Some general concerns bear mentioning here, however:</p>
<p>HTML is scripted language, and has a large number of APIs (some
of which are described in this document). Script can expose the
user to potential risks of information leakage, credential
leakage, cross-site scripting attacks, cross-site request
forgeries, and a host of other problems. While the designs in this
specification are intended to be safe if implemented correctly, a
full implementation is a massive undertaking and, as with any
software, user agents are likely to have security bugs.</p>
<p>Even without scripting, there are specific features in HTML
which, for historical reasons, are required for broad
compatibility with legacy content but that expose the user to
unfortunate security problems. In particular, the <code><a href="embedded-content-1.html#the-img-element">img</a></code>
element can be used in conjunction with some other features as a
way to effect a port scan from the user's location on the
Internet. This can expose local network topologies that the
attacker would otherwise not be able to determine.</p>
<p>HTML relies on a compartmentalization scheme sometimes known as
the <i>same-origin policy</i>. An <a href="origin-0.html#origin">origin</a> in most
cases consists of all the pages served from the same host, on the
same port, using the same protocol.</p>
<p>It is critical, therefore, to ensure that any untrusted content
that forms part of a site be hosted on a different
<a href="origin-0.html#origin">origin</a> than any sensitive content on that site.
Untrusted content can easily spoof any other page on the same
origin, read data from that origin, cause scripts in that origin
to execute, submit forms to and from that origin even if they are
protected from cross-site request forgery attacks by unique
tokens, and make use of any third-party resources exposed to or
rights granted to that origin.</p>
</dd>
<dt>Interoperability considerations:</dt>
<dd>
Rules for processing both conforming and non-conforming content
are defined in this specification.
</dd>
<dt>Published specification:</dt>
<dd id="authors-using-html">
This document is the relevant specification. Labeling a resource
with the <code><a href="#text-html">text/html</a></code> type asserts that the resource is
an <a href="dom.html#html-documents" title="HTML documents">HTML document</a> using
<a href="syntax.html#syntax">the HTML syntax</a>.
</dd>
<dt>Applications that use this media type:</dt>
<dd>
Web browsers, tools for processing Web content, HTML authoring
tools, search engines, validators.
</dd>
<dt>Additional information:</dt>
<dd>
<dl><dt>Magic number(s):</dt>
<dd>No sequence of bytes can uniquely identify an HTML
document. More information on detecting HTML documents is
available in the Media Type Sniffing specification. <a href="references.html#refsMIMESNIFF">[MIMESNIFF]</a></dd>
<dt>File extension(s):</dt>
<dd>"<code title="">html</code>" and "<code title="">htm</code>"
are commonly, but certainly not exclusively, used as the
extension for HTML documents.</dd>
<dt>Macintosh file type code(s):</dt>
<dd><code title="">TEXT</code></dd>
</dl></dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>No restrictions apply.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C</dd>
</dl><p>Fragment identifiers used with <code><a href="#text-html">text/html</a></code> resources
refer to <a href="history.html#the-indicated-part-of-the-document">the indicated part of the document</a>.</p><h3 id="text-html-sandboxed"><span class="secno">12.2 </span><dfn><code>text/html-sandboxed</code></dfn></h3><p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p><dl><dt>Type name:</dt>
<dd>text</dd>
<dt>Subtype name:</dt>
<dd>html-sandboxed</dd>
<dt>Required parameters:</dt>
<dd>No required parameters</dd>
<dt>Optional parameters:</dt>
<dd>Same as for <code><a href="#text-html">text/html</a></code></dd>
<dt>Encoding considerations:</dt>
<dd>Same as for <code><a href="#text-html">text/html</a></code></dd>
<dt>Security considerations:</dt>
<dd>
<p>The purpose of the <code><a href="#text-html-sandboxed">text/html-sandboxed</a></code> MIME type
is to provide a way for content providers to indicate that they
want the file to be interpreted in a manner that does not give the
file's contents access to the rest of the site. This is achieved
by assigning the <code><a href="infrastructure.html#document">Document</a></code> objects generated from
resources labeled as <code><a href="#text-html-sandboxed">text/html-sandboxed</a></code> unique
origins.</p>
<p>To avoid having legacy user agents treating resources labeled
as <code><a href="#text-html-sandboxed">text/html-sandboxed</a></code> as regular
<code><a href="#text-html">text/html</a></code> files, authors should avoid using the <code title="">.html</code> or <code title="">.htm</code> extensions for
resources labeled as <code><a href="#text-html-sandboxed">text/html-sandboxed</a></code>.</p>
<p>Furthermore, since the <code><a href="#text-html-sandboxed">text/html-sandboxed</a></code> MIME
type impacts the origin security model, authors should be careful
to prevent tampering with the MIME type labeling mechanism itself
when documents are labeled as <code><a href="#text-html-sandboxed">text/html-sandboxed</a></code>. If
an attacker can cause a file to be served as
<code><a href="#text-html">text/html</a></code> instead of
<code><a href="#text-html-sandboxed">text/html-sandboxed</a></code>, then the sandboxing will not
take effect and a cross-site scripting attack will become
possible.</p>
<p>Beyond this, the type is identical to <code><a href="#text-html">text/html</a></code>,
and the same considerations apply.</p>
</dd>
<dt>Interoperability considerations:</dt>
<dd>Same as for <code><a href="#text-html">text/html</a></code></dd>
<dt>Published specification:</dt>
<dd>
This document is the relevant specification. Labeling a resource
with the <code><a href="#text-html-sandboxed">text/html-sandboxed</a></code> type asserts that the
resource is an <a href="dom.html#html-documents" title="HTML documents">HTML document</a>
using <a href="syntax.html#syntax">the HTML syntax</a>.
</dd>
<dt>Applications that use this media type:</dt>
<dd>Same as for <code><a href="#text-html">text/html</a></code></dd>
<dt>Additional information:</dt>
<dd>
<dl><dt>Magic number(s):</dt>
<dd>Documents labeled as <code><a href="#text-html-sandboxed">text/html-sandboxed</a></code> are
heuristically indistinguishable from those labeled as
<code><a href="#text-html">text/html</a></code>.</dd>
<dt>File extension(s):</dt>
<dd>"<code title="">sandboxed</code>"</dd>
<dt>Macintosh file type code(s):</dt>
<dd><code title="">TEXT</code></dd>
</dl></dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>No restrictions apply.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C</dd>
</dl><p>Fragment identifiers used with <code><a href="#text-html-sandboxed">text/html-sandboxed</a></code>
resources refer to <a href="history.html#the-indicated-part-of-the-document">the indicated part of the
document</a>.</p><h3 id="application-xhtml-xml"><span class="secno">12.3 </span><dfn><code>application/xhtml+xml</code></dfn></h3><p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p><dl><dt>Type name:</dt>
<dd>application</dd>
<dt>Subtype name:</dt>
<dd>xhtml+xml</dd>
<dt>Required parameters:</dt>
<dd>Same as for <code>application/xml</code> <a href="references.html#refsRFC3023">[RFC3023]</a></dd>
<dt>Optional parameters:</dt>
<dd>Same as for <code>application/xml</code> <a href="references.html#refsRFC3023">[RFC3023]</a></dd>
<dt>Encoding considerations:</dt>
<dd>Same as for <code>application/xml</code> <a href="references.html#refsRFC3023">[RFC3023]</a></dd>
<dt>Security considerations:</dt>
<dd>Same as for <code>application/xml</code> <a href="references.html#refsRFC3023">[RFC3023]</a></dd>
<dt>Interoperability considerations:</dt>
<dd>Same as for <code>application/xml</code> <a href="references.html#refsRFC3023">[RFC3023]</a></dd>
<dt id="authors-using-xhtml">Published specification:</dt>
<dd>
Labeling a resource with the <code><a href="#application-xhtml-xml">application/xhtml+xml</a></code>
type asserts that the resource is an XML document that likely has
a root element from the <a href="namespaces.html#html-namespace-0">HTML namespace</a>. As such, the
relevant specifications are the XML specification, the Namespaces
in XML specification, and this specification. <a href="references.html#refsXML">[XML]</a> <a href="references.html#refsXMLNS">[XMLNS]</a>
</dd>
<dt>Applications that use this media type:</dt>
<dd>Same as for <code>application/xml</code> <a href="references.html#refsRFC3023">[RFC3023]</a></dd>
<dt>Additional information:</dt>
<dd>
<dl><dt>Magic number(s):</dt>
<dd>Same as for <code>application/xml</code> <a href="references.html#refsRFC3023">[RFC3023]</a></dd>
<dt>File extension(s):</dt>
<dd>"<code title="">xhtml</code>" and "<code title="">xht</code>"
are sometimes used as extensions for XML resources that have a
root element from the <a href="namespaces.html#html-namespace-0">HTML namespace</a>.</dd>
<dt>Macintosh file type code(s):</dt>
<dd><code title="">TEXT</code></dd>
</dl></dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>No restrictions apply.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C</dd>
</dl><p>Fragment identifiers used with <code><a href="#application-xhtml-xml">application/xhtml+xml</a></code>
resources have the same semantics as with any <a href="infrastructure.html#xml-mime-type">XML MIME
type</a>. <a href="references.html#refsRFC3023">[RFC3023]</a></p><h3 id="text-cache-manifest"><span class="secno">12.4 </span><dfn><code>text/cache-manifest</code></dfn></h3><p>This registration is for community review and will be submitted
to the IESG for review, approval, and registration with IANA.</p><dl><dt>Type name:</dt>
<dd>text</dd>
<dt>Subtype name:</dt>
<dd>cache-manifest</dd>
<dt>Required parameters:</dt>
<dd>No parameters</dd>
<dt>Optional parameters:</dt>
<dd>No parameters</dd>
<dt>Encoding considerations:</dt>
<dd>Always UTF-8.</dd>
<dt>Security considerations:</dt>
<dd>
<p>Cache manifests themselves pose no immediate risk unless
sensitive information is included within the
manifest. Implementations, however, are required to follow
specific rules when populating a cache based on a cache manifest,
to ensure that certain origin-based restrictions are
honored. Failure to correctly implement these rules can result in
information leakage, cross-site scripting attacks, and the
like.</p>
</dd>
<dt>Interoperability considerations:</dt>
<dd>
Rules for processing both conforming and non-conforming content
are defined in this specification.
</dd>
<dt>Published specification:</dt>
<dd>
This document is the relevant specification.
</dd>
<dt>Applications that use this media type:</dt>
<dd>
Web browsers.
</dd>
<dt>Additional information:</dt>
<dd>
<dl><dt>Magic number(s):</dt>
<dd>Cache manifests begin with the string "<code title="">CACHE
MANIFEST</code>", followed by either a U+0020 SPACE character, a
U+0009 CHARACTER TABULATION (tab) character, a U+000A LINE FEED
(LF) character, or a U+000D CARRIAGE RETURN (CR) character.</dd>
<dt>File extension(s):</dt>
<dd>"<code title="">appcache</code>"</dd>
<dt>Macintosh file type code(s):</dt>
<dd>No specific Macintosh file type codes are recommended for this type.</dd>
</dl></dd>
<dt>Person & email address to contact for further information:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Intended usage:</dt>
<dd>Common</dd>
<dt>Restrictions on usage:</dt>
<dd>No restrictions apply.</dd>
<dt>Author:</dt>
<dd>Ian Hickson <ian@hixie.ch></dd>
<dt>Change controller:</dt>
<dd>W3C</dd>
</dl><p>Fragment identifiers have no meaning with
<code><a href="#text-cache-manifest">text/cache-manifest</a></code> resources.</p></body></html>