docs/manual/mod/mod_negotiation.html.en - httpd - Git at Google

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 <p class="apache">Apache HTTP Server Version 2.0</p>
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 <a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.0</a> &gt; <a href="./">Modules</a></div>
 <div id="page-content">
 <div class="retired"><h4>Please note</h4>
             <p>This document refers to the <strong>2.0</strong> version of Apache httpd, which <strong>is no longer maintained</strong>. Upgrade, and refer to the current version of httpd instead, documented at:</p>
         <ul><li><a href="http://httpd.apache.org/docs/current/">Current release version of Apache HTTP Server documentation</a></li></ul><p>You may follow <a href="http://httpd.apache.org/docs/current/mod/mod_negotiation.html">this link</a> to go to the current version of this document.</p></div><div id="preamble"><h1>Apache Module mod_negotiation</h1>
 <div class="toplang">
 <p><span>Available Languages: </span><a href="../en/mod/mod_negotiation.html" title="English">&nbsp;en&nbsp;</a> |
 <a href="../ja/mod/mod_negotiation.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a></p>
 </div>
 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Provides for <a href="../content-negotiation.html">content negotiation</a></td></tr>
 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Base</td></tr>
 <tr><th><a href="module-dict.html#ModuleIdentifier">Module&#160;Identifier:</a></th><td>negotiation_module</td></tr>
 <tr><th><a href="module-dict.html#SourceFile">Source&#160;File:</a></th><td>mod_negotiation.c</td></tr></table>
 <h3>Summary</h3>

     <p>Content negotiation, or more accurately content selection, is
     the selection of the document that best matches the clients
     capabilities, from one of several available documents. There
     are two implementations of this.</p>

     <ul>
       <li>A type map (a file with the handler
       <code>type-map</code>) which explicitly lists the files
       containing the variants.</li>

       <li>A MultiViews search (enabled by the <code>MultiViews</code>
       <code class="directive"><a href="../mod/core.html#options">Options</a></code>), where the server does
       an implicit filename pattern match, and choose from amongst the
       results.</li>
     </ul>
 </div>
 <div id="quickview"><h3 class="directives">Directives</h3>
 <ul id="toc">
 <li><img alt="" src="../images/down.gif" /> <a href="#cachenegotiateddocs">CacheNegotiatedDocs</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#forcelanguagepriority">ForceLanguagePriority</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#languagepriority">LanguagePriority</a></li>
 </ul>
 <h3>Topics</h3>
 <ul id="topics">
 <li><img alt="" src="../images/down.gif" /> <a href="#typemaps">Type maps</a></li>
 <li><img alt="" src="../images/down.gif" /> <a href="#multiviews">MultiViews</a></li>
 </ul><h3>See also</h3>
 <ul class="seealso">
 <li><code class="directive"><a href="../mod/core.html#options">Options</a></code></li>
 <li><code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code></li>
 <li><a href="../content-negotiation.html">Content
 Negotiation</a></li>
 <li><a href="../env.html">Environment Variables</a></li>
 </ul></div>
 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="typemaps" id="typemaps">Type maps</a></h2>
     <p>A type map has a format similar to RFC822 mail headers. It
     contains document descriptions separated by blank lines, with
     lines beginning with a hash character ('#') treated as
     comments. A document description consists of several header
     records; records may be continued on multiple lines if the
     continuation lines start with spaces. The leading space will be
     deleted and the lines concatenated. A header record consists of
     a keyword name, which always ends in a colon, followed by a
     value. Whitespace is allowed between the header name and value,
     and between the tokens of value. The headers allowed are: </p>

     <dl>
       <dt><code>Content-Encoding:</code></dt>
       <dd>The encoding of the file. Apache only recognizes
       encodings that are defined by an <code class="directive"><a href="../mod/mod_mime.html#addencoding">AddEncoding</a></code> directive.
       This normally includes the encodings <code>x-compress</code>
       for compress'd files, and <code>x-gzip</code> for gzip'd
       files. The <code>x-</code> prefix is ignored for encoding
       comparisons.</dd>

       <dt><code>Content-Language:</code></dt>
       <dd>The language(s) of the variant, as an Internet standard
       language tag (<a href="http://www.ietf.org/rfc/rfc1766.txt">RFC 1766</a>). An example is <code>en</code>,
       meaning English. If the variant contains more than one
       language, they are separated by a comma.</dd>

       <dt><code>Content-Length:</code></dt>
       <dd>The length of the file, in bytes. If this header is not
       present, then the actual length of the file is used.</dd>

       <dt><code>Content-Type:</code></dt>

       <dd>
         The MIME media type of the document, with optional
         parameters. Parameters are separated from the media type
         and from one another by a semi-colon, with a syntax of
         <code>name=value</code>. Common parameters include:

         <dl>
           <dt><code>level</code></dt>
           <dd>an integer specifying the version of the media type.
           For <code>text/html</code> this defaults to 2, otherwise
           0.</dd>

           <dt><code>qs</code></dt>
           <dd>a floating-point number with a value in the range 0.0
           to 1.0, indicating the relative 'quality' of this variant
           compared to the other available variants, independent of
           the client's capabilities. For example, a jpeg file is
           usually of higher source quality than an ascii file if it
           is attempting to represent a photograph. However, if the
           resource being represented is ascii art, then an ascii
           file would have a higher source quality than a jpeg file.
           All <code>qs</code> values are therefore specific to a given
           resource.</dd>
         </dl>

         <div class="example"><h3>Example</h3><p><code>
           Content-Type: image/jpeg; qs=0.8
         </code></p></div>
       </dd>

       <dt><code>URI:</code></dt>
       <dd>uri of the file containing the variant (of the given
       media type, encoded with the given content encoding). These
       are interpreted as URLs relative to the map file; they must
       be on the same server (!), and they must refer to files to
       which the client would be granted access if they were to be
       requested directly.</dd>

       <dt><code>Body:</code></dt>
       <dd>New in Apache 2.0, the actual content of the resource may
       be included in the type-map file using the Body header.  This
       header must contain a string that designates a delimiter for
       the body content. Then all following lines in the type map
       file will be considered part of the resource body until the
       delimiter string is found.

       <div class="example"><h3>Example:</h3><p><code>
         Body:----xyz----<br />
         &lt;html&gt;<br />
         &lt;body&gt;<br />
         &lt;p&gt;Content of the page.&lt;/p&gt;<br />
         &lt;/body&gt;<br />
         &lt;/html&gt;<br />
         ----xyz----
       </code></p></div>
       </dd>
     </dl>
 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="multiviews" id="multiviews">MultiViews</a></h2>
     <p>A MultiViews search is enabled by the <code>MultiViews</code>
     <code class="directive"><a href="../mod/core.html#options">Options</a></code>. If the server receives a
     request for <code>/some/dir/foo</code> and
     <code>/some/dir/foo</code> does <em>not</em> exist, then the
     server reads the directory looking for all files named
     <code>foo.*</code>, and effectively fakes up a type map which
     names all those files, assigning them the same media types and
     content-encodings it would have if the client had asked for one
     of them by name. It then chooses the best match to the client's
     requirements, and returns that document.</p>

     <p>The <code class="directive"><a href="../mod/mod_mime.html#multiviewsmatch">MultiViewsMatch</a></code>
     directive configures whether Apache will consider files
     that do not have content negotiation meta-information assigned
     to them when choosing files.</p>
 </div>
 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="directive-section"><h2><a name="CacheNegotiatedDocs" id="CacheNegotiatedDocs">CacheNegotiatedDocs</a> <a name="cachenegotiateddocs" id="cachenegotiateddocs">Directive</a></h2>
 <table class="directive">
 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Allows content-negotiated documents to be
 cached by proxy servers</td></tr>
 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheNegotiatedDocs On|Off</code></td></tr>
 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CacheNegotiatedDocs Off</code></td></tr>
 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_negotiation</td></tr>
 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The syntax changed in version 2.0.</td></tr>
 </table>
     <p>If set, this directive allows content-negotiated documents
     to be cached by proxy servers. This could mean that clients
     behind those proxys could retrieve versions of the documents
     that are not the best match for their abilities, but it will
     make caching more efficient.</p>

     <p>This directive only applies to requests which come from
     HTTP/1.0 browsers. HTTP/1.1 provides much better control over
     the caching of negotiated documents, and this directive has no
     effect in responses to HTTP/1.1 requests.</p>

     <p>Prior to version 2.0,
     <code class="directive">CacheNegotiatedDocs</code> did not take an
     argument; it was turned on by the presence of the directive by
     itself.</p>

 </div>
 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="directive-section"><h2><a name="ForceLanguagePriority" id="ForceLanguagePriority">ForceLanguagePriority</a> <a name="forcelanguagepriority" id="forcelanguagepriority">Directive</a></h2>
 <table class="directive">
 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Action to take if a single acceptable document is not
 found</td></tr>
 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ForceLanguagePriority None|Prefer|Fallback [Prefer|Fallback]</code></td></tr>
 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ForceLanguagePriority Prefer</code></td></tr>
 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_negotiation</td></tr>
 <tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.0.30 and later</td></tr>
 </table>
     <p>The <code class="directive">ForceLanguagePriority</code> directive uses
     the given <code class="directive"><a href="#languagepriority">LanguagePriority</a></code> to satisfy
     negotation where the server could otherwise not return a single
     matching document.</p>

     <p><code>ForceLanguagePriority Prefer</code> uses
     <code>LanguagePriority</code> to serve a one valid result, rather
     than returning an HTTP result 300 (MULTIPLE CHOICES) when there
     are several equally valid choices.  If the directives below were
     given, and the user's <code>Accept-Language</code> header assigned
     <code>en</code> and <code>de</code> each as quality <code>.500</code>
     (equally acceptable) then the first matching variant, <code>en</code>,
     will be served.</p>

     <div class="example"><p><code>
       LanguagePriority en fr de<br />
       ForceLanguagePriority Prefer
     </code></p></div>

     <p><code>ForceLanguagePriority Fallback</code> uses
     <code class="directive"><a href="#languagepriority">LanguagePriority</a></code> to
     serve a valid result, rather than returning an HTTP result 406
     (NOT ACCEPTABLE). If the directives below were given, and the user's
     <code>Accept-Language</code> only permitted an <code>es</code>
     language response, but such a variant isn't found, then the first
     variant from the <code class="directive"><a href="#languagepriority">LanguagePriority</a></code> list below will be served.</p>

     <div class="example"><p><code>
       LanguagePriority en fr de<br />
       ForceLanguagePriority Fallback
     </code></p></div>

     <p>Both options, <code>Prefer</code> and <code>Fallback</code>, may be
     specified, so either the first matching variant from <code class="directive"><a href="#languagepriority">LanguagePriority</a></code> will be served if
     more than one variant is acceptable, or first available document will
     be served if none of the variants matched the client's acceptable list
     of languages.</p>

 <h3>See also</h3>
 <ul>
 <li><code class="directive"><a href="../mod/mod_mime.html#addlanguage">AddLanguage</a></code></li>
 </ul>
 </div>
 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
 <div class="directive-section"><h2><a name="LanguagePriority" id="LanguagePriority">LanguagePriority</a> <a name="languagepriority" id="languagepriority">Directive</a></h2>
 <table class="directive">
 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The precendence of language variants for cases where
 the client does not express a preference</td></tr>
 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LanguagePriority <var>MIME-lang</var> [<var>MIME-lang</var>]
 ...</code></td></tr>
 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
 <tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_negotiation</td></tr>
 </table>
     <p>The <code class="directive">LanguagePriority</code> sets the precedence
     of language variants for the case where the client does not
     express a preference, when handling a MultiViews request. The list
     of <var>MIME-lang</var> are in order of decreasing preference.</p>

     <div class="example"><h3>Example:</h3><p><code>
       LanguagePriority en fr de
     </code></p></div>

     <p>For a request for <code>foo.html</code>, where
     <code>foo.html.fr</code> and <code>foo.html.de</code> both
     existed, but the browser did not express a language preference,
     then <code>foo.html.fr</code> would be returned.</p>

     <p>Note that this directive only has an effect if a 'best'
     language cannot be determined by any other means or the <code class="directive"><a href="#forcelanguagepriority">ForceLanguagePriority</a></code> directive
     is not <code>None</code>. In general, the client determines the
     language preference, not the server.</p>

 <h3>See also</h3>
 <ul>
 <li><code class="directive"><a href="../mod/mod_mime.html#addlanguage">AddLanguage</a></code></li>
 </ul>
 </div>
 </div>
 <div class="bottomlang">
 <p><span>Available Languages: </span><a href="../en/mod/mod_negotiation.html" title="English">&nbsp;en&nbsp;</a> |
 <a href="../ja/mod/mod_negotiation.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a></p>
 </div><div id="footer">
 <p class="apache">Copyright 2013 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div>
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	<title>mod_negotiation - Apache HTTP Server</title>
	<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
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	<body>
	<div id="page-header">
	<p class="menu"><a href="../mod/">Modules</a> \| <a href="../mod/directives.html">Directives</a> \| <a href="../faq/">FAQ</a> \| <a href="../glossary.html">Glossary</a> \| <a href="../sitemap.html">Sitemap</a></p>
	<p class="apache">Apache HTTP Server Version 2.0</p>
	<img alt="" src="../images/feather.gif" /></div>
	<div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
	<div id="path">
	<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.0</a> > <a href="./">Modules</a></div>
	<div id="page-content">
	<div class="retired"><h4>Please note</h4>
	<p>This document refers to the <strong>2.0</strong> version of Apache httpd, which <strong>is no longer maintained</strong>. Upgrade, and refer to the current version of httpd instead, documented at:</p>
	<ul><li><a href="http://httpd.apache.org/docs/current/">Current release version of Apache HTTP Server documentation</a></li></ul><p>You may follow <a href="http://httpd.apache.org/docs/current/mod/mod_negotiation.html">this link</a> to go to the current version of this document.</p></div><div id="preamble"><h1>Apache Module mod_negotiation</h1>
	<div class="toplang">
	<p><span>Available Languages: </span><a href="../en/mod/mod_negotiation.html" title="English"> en </a> \|
	<a href="../ja/mod/mod_negotiation.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
	</div>
	<table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Provides for <a href="../content-negotiation.html">content negotiation</a></td></tr>
	<tr><th><a href="module-dict.html#Status">Status:</a></th><td>Base</td></tr>
	<tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>negotiation_module</td></tr>
	<tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_negotiation.c</td></tr></table>
	<h3>Summary</h3>

	<p>Content negotiation, or more accurately content selection, is
	the selection of the document that best matches the clients
	capabilities, from one of several available documents. There
	are two implementations of this.</p>

	<ul>
	<li>A type map (a file with the handler
	<code>type-map</code>) which explicitly lists the files
	containing the variants.</li>

	<li>A MultiViews search (enabled by the <code>MultiViews</code>
	<code class="directive"><a href="../mod/core.html#options">Options</a></code>), where the server does
	an implicit filename pattern match, and choose from amongst the
	results.</li>
	</ul>
	</div>
	<div id="quickview"><h3 class="directives">Directives</h3>
	<ul id="toc">
	<li><img alt="" src="../images/down.gif" /> <a href="#cachenegotiateddocs">CacheNegotiatedDocs</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#forcelanguagepriority">ForceLanguagePriority</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#languagepriority">LanguagePriority</a></li>
	</ul>
	<h3>Topics</h3>
	<ul id="topics">
	<li><img alt="" src="../images/down.gif" /> <a href="#typemaps">Type maps</a></li>
	<li><img alt="" src="../images/down.gif" /> <a href="#multiviews">MultiViews</a></li>
	</ul><h3>See also</h3>
	<ul class="seealso">
	<li><code class="directive"><a href="../mod/core.html#options">Options</a></code></li>
	<li><code class="module"><a href="../mod/mod_mime.html">mod_mime</a></code></li>
	<li><a href="../content-negotiation.html">Content
	Negotiation</a></li>
	<li><a href="../env.html">Environment Variables</a></li>
	</ul></div>
	<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="typemaps" id="typemaps">Type maps</a></h2>
	<p>A type map has a format similar to RFC822 mail headers. It
	contains document descriptions separated by blank lines, with
	lines beginning with a hash character ('#') treated as
	comments. A document description consists of several header
	records; records may be continued on multiple lines if the
	continuation lines start with spaces. The leading space will be
	deleted and the lines concatenated. A header record consists of
	a keyword name, which always ends in a colon, followed by a
	value. Whitespace is allowed between the header name and value,
	and between the tokens of value. The headers allowed are: </p>

	<dl>
	<dt><code>Content-Encoding:</code></dt>
	<dd>The encoding of the file. Apache only recognizes
	encodings that are defined by an <code class="directive"><a href="../mod/mod_mime.html#addencoding">AddEncoding</a></code> directive.
	This normally includes the encodings <code>x-compress</code>
	for compress'd files, and <code>x-gzip</code> for gzip'd
	files. The <code>x-</code> prefix is ignored for encoding
	comparisons.</dd>

	<dt><code>Content-Language:</code></dt>
	<dd>The language(s) of the variant, as an Internet standard
	language tag (<a href="http://www.ietf.org/rfc/rfc1766.txt">RFC 1766</a>). An example is <code>en</code>,
	meaning English. If the variant contains more than one
	language, they are separated by a comma.</dd>

	<dt><code>Content-Length:</code></dt>
	<dd>The length of the file, in bytes. If this header is not
	present, then the actual length of the file is used.</dd>

	<dt><code>Content-Type:</code></dt>

	<dd>
	The MIME media type of the document, with optional
	parameters. Parameters are separated from the media type
	and from one another by a semi-colon, with a syntax of
	<code>name=value</code>. Common parameters include:

	<dl>
	<dt><code>level</code></dt>
	<dd>an integer specifying the version of the media type.
	For <code>text/html</code> this defaults to 2, otherwise
	0.</dd>

	<dt><code>qs</code></dt>
	<dd>a floating-point number with a value in the range 0.0
	to 1.0, indicating the relative 'quality' of this variant
	compared to the other available variants, independent of
	the client's capabilities. For example, a jpeg file is
	usually of higher source quality than an ascii file if it
	is attempting to represent a photograph. However, if the
	resource being represented is ascii art, then an ascii
	file would have a higher source quality than a jpeg file.
	All <code>qs</code> values are therefore specific to a given
	resource.</dd>
	</dl>

	<div class="example"><h3>Example</h3><p><code>
	Content-Type: image/jpeg; qs=0.8
	</code></p></div>
	</dd>

	<dt><code>URI:</code></dt>
	<dd>uri of the file containing the variant (of the given
	media type, encoded with the given content encoding). These
	are interpreted as URLs relative to the map file; they must
	be on the same server (!), and they must refer to files to
	which the client would be granted access if they were to be
	requested directly.</dd>

	<dt><code>Body:</code></dt>
	<dd>New in Apache 2.0, the actual content of the resource may
	be included in the type-map file using the Body header. This
	header must contain a string that designates a delimiter for
	the body content. Then all following lines in the type map
	file will be considered part of the resource body until the
	delimiter string is found.

	<div class="example"><h3>Example:</h3><p><code>
	Body:----xyz----<br />
	<html><br />
	<body><br />
	<p>Content of the page.</p><br />
	</body><br />
	</html><br />
	----xyz----
	</code></p></div>
	</dd>
	</dl>
	</div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="multiviews" id="multiviews">MultiViews</a></h2>
	<p>A MultiViews search is enabled by the <code>MultiViews</code>
	<code class="directive"><a href="../mod/core.html#options">Options</a></code>. If the server receives a
	request for <code>/some/dir/foo</code> and
	<code>/some/dir/foo</code> does <em>not</em> exist, then the
	server reads the directory looking for all files named
	<code>foo.*</code>, and effectively fakes up a type map which
	names all those files, assigning them the same media types and
	content-encodings it would have if the client had asked for one
	of them by name. It then chooses the best match to the client's
	requirements, and returns that document.</p>

	<p>The <code class="directive"><a href="../mod/mod_mime.html#multiviewsmatch">MultiViewsMatch</a></code>
	directive configures whether Apache will consider files
	that do not have content negotiation meta-information assigned
	to them when choosing files.</p>
	</div>
	<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="directive-section"><h2><a name="CacheNegotiatedDocs" id="CacheNegotiatedDocs">CacheNegotiatedDocs</a> <a name="cachenegotiateddocs" id="cachenegotiateddocs">Directive</a></h2>
	<table class="directive">
	<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Allows content-negotiated documents to be
	cached by proxy servers</td></tr>
	<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheNegotiatedDocs On\|Off</code></td></tr>
	<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CacheNegotiatedDocs Off</code></td></tr>
	<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
	<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
	<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_negotiation</td></tr>
	<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>The syntax changed in version 2.0.</td></tr>
	</table>
	<p>If set, this directive allows content-negotiated documents
	to be cached by proxy servers. This could mean that clients
	behind those proxys could retrieve versions of the documents
	that are not the best match for their abilities, but it will
	make caching more efficient.</p>

	<p>This directive only applies to requests which come from
	HTTP/1.0 browsers. HTTP/1.1 provides much better control over
	the caching of negotiated documents, and this directive has no
	effect in responses to HTTP/1.1 requests.</p>

	<p>Prior to version 2.0,
	<code class="directive">CacheNegotiatedDocs</code> did not take an
	argument; it was turned on by the presence of the directive by
	itself.</p>

	</div>
	<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="directive-section"><h2><a name="ForceLanguagePriority" id="ForceLanguagePriority">ForceLanguagePriority</a> <a name="forcelanguagepriority" id="forcelanguagepriority">Directive</a></h2>
	<table class="directive">
	<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Action to take if a single acceptable document is not
	found</td></tr>
	<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>ForceLanguagePriority None\|Prefer\|Fallback [Prefer\|Fallback]</code></td></tr>
	<tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>ForceLanguagePriority Prefer</code></td></tr>
	<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
	<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
	<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
	<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_negotiation</td></tr>
	<tr><th><a href="directive-dict.html#Compatibility">Compatibility:</a></th><td>Available in version 2.0.30 and later</td></tr>
	</table>
	<p>The <code class="directive">ForceLanguagePriority</code> directive uses
	the given <code class="directive"><a href="#languagepriority">LanguagePriority</a></code> to satisfy
	negotation where the server could otherwise not return a single
	matching document.</p>

	<p><code>ForceLanguagePriority Prefer</code> uses
	<code>LanguagePriority</code> to serve a one valid result, rather
	than returning an HTTP result 300 (MULTIPLE CHOICES) when there
	are several equally valid choices. If the directives below were
	given, and the user's <code>Accept-Language</code> header assigned
	<code>en</code> and <code>de</code> each as quality <code>.500</code>
	(equally acceptable) then the first matching variant, <code>en</code>,
	will be served.</p>

	<div class="example"><p><code>
	LanguagePriority en fr de<br />
	ForceLanguagePriority Prefer
	</code></p></div>

	<p><code>ForceLanguagePriority Fallback</code> uses
	<code class="directive"><a href="#languagepriority">LanguagePriority</a></code> to
	serve a valid result, rather than returning an HTTP result 406
	(NOT ACCEPTABLE). If the directives below were given, and the user's
	<code>Accept-Language</code> only permitted an <code>es</code>
	language response, but such a variant isn't found, then the first
	variant from the <code class="directive"><a href="#languagepriority">LanguagePriority</a></code> list below will be served.</p>

	<div class="example"><p><code>
	LanguagePriority en fr de<br />
	ForceLanguagePriority Fallback
	</code></p></div>

	<p>Both options, <code>Prefer</code> and <code>Fallback</code>, may be
	specified, so either the first matching variant from <code class="directive"><a href="#languagepriority">LanguagePriority</a></code> will be served if
	more than one variant is acceptable, or first available document will
	be served if none of the variants matched the client's acceptable list
	of languages.</p>

	<h3>See also</h3>
	<ul>
	<li><code class="directive"><a href="../mod/mod_mime.html#addlanguage">AddLanguage</a></code></li>
	</ul>
	</div>
	<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
	<div class="directive-section"><h2><a name="LanguagePriority" id="LanguagePriority">LanguagePriority</a> <a name="languagepriority" id="languagepriority">Directive</a></h2>
	<table class="directive">
	<tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The precendence of language variants for cases where
	the client does not express a preference</td></tr>
	<tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>LanguagePriority <var>MIME-lang</var> [<var>MIME-lang</var>]
	...</code></td></tr>
	<tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host, directory, .htaccess</td></tr>
	<tr><th><a href="directive-dict.html#Override">Override:</a></th><td>FileInfo</td></tr>
	<tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Base</td></tr>
	<tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_negotiation</td></tr>
	</table>
	<p>The <code class="directive">LanguagePriority</code> sets the precedence
	of language variants for the case where the client does not
	express a preference, when handling a MultiViews request. The list
	of <var>MIME-lang</var> are in order of decreasing preference.</p>

	<div class="example"><h3>Example:</h3><p><code>
	LanguagePriority en fr de
	</code></p></div>

	<p>For a request for <code>foo.html</code>, where
	<code>foo.html.fr</code> and <code>foo.html.de</code> both
	existed, but the browser did not express a language preference,
	then <code>foo.html.fr</code> would be returned.</p>

	<p>Note that this directive only has an effect if a 'best'
	language cannot be determined by any other means or the <code class="directive"><a href="#forcelanguagepriority">ForceLanguagePriority</a></code> directive
	is not <code>None</code>. In general, the client determines the
	language preference, not the server.</p>

	<h3>See also</h3>
	<ul>
	<li><code class="directive"><a href="../mod/mod_mime.html#addlanguage">AddLanguage</a></code></li>
	</ul>
	</div>
	</div>
	<div class="bottomlang">
	<p><span>Available Languages: </span><a href="../en/mod/mod_negotiation.html" title="English"> en </a> \|
	<a href="../ja/mod/mod_negotiation.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a></p>
	</div><div id="footer">
	<p class="apache">Copyright 2013 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
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