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Posted to cvs@httpd.apache.org by rb...@apache.org on 2010/03/12 15:19:08 UTC
svn commit: r922267 - in /httpd/httpd/trunk/docs/manual:
custom-error.html.en custom-error.xml
Author: rbowen
Date: Fri Mar 12 14:19:08 2010
New Revision: 922267
URL: http://svn.apache.org/viewvc?rev=922267&view=rev
Log:
I'm not completely satisfied with this, but I need to stop and come back
to it later. This is a complete rewrite, because the original document
was, in fact, the original document - that is, it described how NCSA did
things. Wow.
Modified:
httpd/httpd/trunk/docs/manual/custom-error.html.en
httpd/httpd/trunk/docs/manual/custom-error.xml
Modified: httpd/httpd/trunk/docs/manual/custom-error.html.en
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/manual/custom-error.html.en?rev=922267&r1=922266&r2=922267&view=diff
==============================================================================
--- httpd/httpd/trunk/docs/manual/custom-error.html.en (original)
+++ httpd/httpd/trunk/docs/manual/custom-error.html.en Fri Mar 12 14:19:08 2010
@@ -26,147 +26,122 @@
<a href="./tr/custom-error.html" hreflang="tr" rel="alternate" title="Türkçe"> tr </a></p>
</div>
- <p>Additional functionality allows webmasters to configure the response
- of Apache to some error or problem.</p>
- <p>Customizable responses can be defined to be activated in the event of
- a server detected error or problem.</p>
+ <p>Although the Apache HTTP Server provides generic error responses
+ in the event of 4xx or 5xx HTTP status codes, these responses are
+ rather stark, uninformative, and can be indimidating to site users.
+ You may wish to provide custom error responses which are either
+ friendlier, or in some language other than English, or perhaps which
+ are styled more in line with your site layout.</p>
+
+ <p>Customized error responses can be defined for any HTTP status
+ code designated as an error condition - that is, any 4xx or 5xx
+ status.</p>
+
+ <p>Additionally, a set of values are provided, so
+ that the error document can be customized further based on the
+ values of these variables, using <a href="howto/ssi.html">Server
+ Side Includes</a>. Or, you can have error conditions handled by a
+ cgi program, or other dynamic handler (PHP, mod_perl, etc) which
+ makes use of these variables.</p>
- <p>If a script crashes and produces a "500 Server Error" response,
- then this response can be replaced with either some friendlier text or by
- a redirection to another URL (local or external).</p>
</div>
-<div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#behavior">Behavior</a></li>
-<li><img alt="" src="./images/down.gif" /> <a href="#configuration">Configuration</a></li>
-<li><img alt="" src="./images/down.gif" /> <a href="#custom">Custom Error Responses and Redirects</a></li>
+<div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#configuration">Configuration</a></li>
+<li><img alt="" src="./images/down.gif" /> <a href="#variables">Available Variables</a></li>
+<li><img alt="" src="./images/down.gif" /> <a href="#custom">Customizing Error Responses</a></li>
+<li><img alt="" src="./images/down.gif" /> <a href="#multi-lang">Multi Language Customer Error Documents</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="behavior" id="behavior">Behavior</a></h2>
-
+<h2><a name="configuration" id="configuration">Configuration</a></h2>
- <h3>Old Behavior</h3>
-
+ <p>Custom error documents are configured using the <code class="directive"><a href="./mod/core.html#errordocument">ErrorDocument</a></code> directive.
+ <code>ErrorDocument</code>, which may be used in global,
+ virtualhost, or directory context. It may be used in .htaccess files
+ if <code class="directive"><a href="./mod/core.html#allowoverride">AllowOverride</a></code> is set to
+ FileInfo.</p>
- <p>NCSA httpd 1.3 would return some boring old error/problem message
- which would often be meaningless to the user, and would provide no
- means of logging the symptoms which caused it.</p>
-
+ <div class="example"><p><code>
+ ErrorDocument 500 "Sorry, our script crashed. Oh dear"<br />
+ ErrorDocument 500 /cgi-bin/crash-recover<br />
+ ErrorDocument 500 http://error.example.com/server_error.html<br />
+ ErrorDocument 404 /errors/not_found.html <br />
+ ErrorDocument 401 /subscription/how_to_subscribe.html
+ </code></p></div>
- <h3>New Behavior</h3>
-
+ <p>The syntax of the <code>ErrorDocuemnt</code> directrive is:</p>
- <p>The server can be asked to:</p>
+ <div class="example"><p><code>
+ ErrorDocument <3-digit-code> <action>
+ </code></p></div>
- <ol>
- <li>Display some other text, instead of the NCSA hard coded
- messages, or</li>
+ <p>where the action can be one of:</p>
- <li>redirect to a local URL, or</li>
+ <ol>
+ <li>Text to be displayed. Wrap the text with quotes (").</li>
+ <li>A local URL to redirect to.</li>
+ <li>An external URL to redirect to.</li>
+ </ol>
+
+ <p>When redirecting to a local URL, additional environment variables
+ are set so that the response can be further customized. They are not sent to
+ external URLs.</p>
- <li>redirect to an external URL.</li>
- </ol>
+ </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="variables" id="variables">Available Variables</a></h2>
<p>Redirecting to another URL can be useful, but only if some
- information can be passed which can then be used to explain and/or log
- the error/problem more clearly.</p>
+ information can be passed which can then be used to explain or log
+ the error condition more clearly.</p>
+
+ <p>To achieve this, when the error redirect is sent, additional
+ environment variables will be set, which will be generated from
+ the headers provided to the original request by prepending
+ 'REDIRECT_' onto the original header name. This provides the error
+ document the context of the original request.</p>
- <p>To achieve this, Apache will define new CGI-like environment
- variables:</p>
+ <p>For example, you might recieve, in addition to more usual
+ environment variables, the following.</p>
<div class="example"><p><code>
- REDIRECT_HTTP_ACCEPT=*/*, image/gif, image/x-xbitmap,
- image/jpeg<br />
- REDIRECT_HTTP_USER_AGENT=Mozilla/1.1b2 (X11; I; HP-UX A.09.05
- 9000/712)<br />
- REDIRECT_PATH=.:/bin:/usr/local/bin:/etc<br />
+ REDIRECT_HTTP_ACCEPT=*/*, image/gif, image/jpeg, image/png<br />
+ REDIRECT_HTTP_USER_AGENT=Mozilla/5.0 Fedora/3.5.8-1.fc12 Firefox/3.5.8<br />
+ REDIRECT_PATH=.:/bin:/usr/local/bin:/sbin<br />
REDIRECT_QUERY_STRING=<br />
REDIRECT_REMOTE_ADDR=121.345.78.123<br />
- REDIRECT_REMOTE_HOST=ooh.ahhh.com<br />
- REDIRECT_SERVER_NAME=crash.bang.edu<br />
+ REDIRECT_REMOTE_HOST=client.example.com<br />
+ REDIRECT_SERVER_NAME=www.example.edu<br />
REDIRECT_SERVER_PORT=80<br />
- REDIRECT_SERVER_SOFTWARE=Apache/0.8.15<br />
+ REDIRECT_SERVER_SOFTWARE=Apache/2.2.15<br />
REDIRECT_URL=/cgi-bin/buggy.pl
</code></p></div>
- <p>Note the <code>REDIRECT_</code> prefix.</p>
+ <p><code>REDIRECT_</code> environment variables are created from
+ the environment variables which existed prior to the
+ redirect. They are renamed with a <code>REDIRECT_</code>
+ prefix, <em>i.e.</em>, <code>HTTP_USER_AGENT</code> becomes
+ <code>REDIRECT_HTTP_USER_AGENT</code>.</p>
+
+ <p><code>REDIRECT_URL</code>, <code>REDIRECT_STATUS</code>, and
+ <code>REDIRECT_QUERY_STRING</code> are guaranteed to be set, and
+ the other headers will be set only if they existed prior to the
+ error condition.</p>
- <p>At least <code>REDIRECT_URL</code> and
- <code>REDIRECT_QUERY_STRING</code> will be passed to the
- new URL (assuming it's a cgi-script or a cgi-include). The
- other variables will exist only if they existed prior to
- the error/problem. <strong>None</strong> of these will be
- set if your <code class="directive"><a href="./mod/core.html#errordocument">ErrorDocument</a></code> is an
+ <p><strong>None</strong> of these will be
+ set if the <code class="directive"><a href="./mod/core.html#errordocument">ErrorDocument</a></code> target is an
<em>external</em> redirect (anything starting with a
scheme name like <code>http:</code>, even if it refers to the same host
as the server).</p>
-
</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
<div class="section">
-<h2><a name="configuration" id="configuration">Configuration</a></h2>
-
-
- <p>Use of <code class="directive"><a href="./mod/core.html#errordocument">ErrorDocument</a></code> is enabled
- for .htaccess files when the
- <code class="directive"><a href="./mod/core.html#allowoverride">AllowOverride</a></code> is set to FileInfo.</p>
+<h2><a name="custom" id="custom">Customizing Error Responses</a></h2>
- <p>Here are some examples...</p>
-
- <div class="example"><p><code>
- ErrorDocument 500 /cgi-bin/crash-recover <br />
- ErrorDocument 500 "Sorry, our script crashed. Oh dear" <br />
- ErrorDocument 500 http://xxx/ <br />
- ErrorDocument 404 /Lame_excuses/not_found.html <br />
- ErrorDocument 401 /Subscription/how_to_subscribe.html
- </code></p></div>
-
- <p>The syntax is,</p>
-
- <div class="example"><p><code>
- ErrorDocument <3-digit-code> <action>
- </code></p></div>
-
- <p>where the action can be,</p>
-
- <ol>
- <li>Text to be displayed. Wrap the text with quotes (").</li>
-
- <li>An external URL to redirect to.</li>
-
- <li>A local URL to redirect to.</li>
- </ol>
- </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
-<div class="section">
-<h2><a name="custom" id="custom">Custom Error Responses and Redirects</a></h2>
-
-
- <p>Apache's behavior to redirected URLs has been modified so
- that additional environment variables are available to a
- script/server-include.</p>
-
- <h3>Old behavior</h3>
-
-
- <p>Standard CGI vars were made available to a script which
- has been redirected to. No indication of where the
- redirection came from was provided.</p>
-
-
- <h3>New behavior</h3>
-
-
- <p>A new batch of environment variables will be initialized
- for use by a script which has been redirected to. Each new
- variable will have the prefix <code>REDIRECT_</code>.
- <code>REDIRECT_</code> environment variables are created from
- the CGI environment variables which existed prior to the
- redirect, they are renamed with a <code>REDIRECT_</code>
- prefix, <em>i.e.</em>, <code>HTTP_USER_AGENT</code> becomes
- <code>REDIRECT_HTTP_USER_AGENT</code>. In addition to these
- new variables, Apache will define <code>REDIRECT_URL</code>
- and <code>REDIRECT_STATUS</code> to help the script trace its
- origin. Both the original URL and the URL being redirected to
- can be logged in the access log.</p>
+ <p>If you point your <code>ErrorDocument</code> to some variety of
+ dynamic handler such as a server-side include document, CGI
+ script, or some variety of other handler, you may wish to use the
+ available custom environent variables to customize this
+ response.</p>
<p>If the ErrorDocument specifies a local redirect to a CGI
script, the script should include a "<code>Status:</code>"
@@ -186,13 +161,46 @@
condition, such as <code>404 Not Found</code>, it can
use the specific code and error text instead.</p>
- <p>Note that the script <em>must</em> emit an appropriate
- <code>Status:</code> header (such as <code>302 Found</code>), if the
- response contains a <code>Location:</code> header (in order to issue a
- client side redirect). Otherwise the <code>Location:</code> header may
- have no effect.</p>
-
- </div></div>
+ <p>Note that if the response contains <code>Location:</code>
+ header (in order to issue a client-side redirect), the script
+ <em>must</em> emit an appropriate <code>Status:</code> header
+ (such as <code>302 Found</code>). Otherwise the
+ <code>Location:</code> header may have no effect.</p>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="multi-lang" id="multi-lang">Multi Language Customer Error Documents</a></h2>
+
+ <p>Provided with your installation of the Apache HTTP Server is a
+ directory of custom error documents translated into 16 different
+ languages. There's also a configuration file in the
+ <code>conf/extra</code> configuration directory that can be included
+ to enable this feature.</p>
+
+ <p>In your server configuration file, you'll see a line such as:</p>
+
+ <div class="example"><p><code>
+ # Multi-language error messages<br />
+ #Include conf/extra/httpd-multilang-errordoc.conf
+ </code></p></div>
+
+ <p>Uncommenting this <code>Include</code> line will enable this
+ feature, and provide language-negotiated error messages, based on
+ the language preference set in the client browser.</p>
+
+ <p>Additionally, these documents contain various of the
+ <code>REDIRECT_</code> variables, so that additional information can
+ be provided to the end-user about what happened, and what they can
+ do now.</p>
+
+ <p>These documents can be customized to whatever degree you wish to
+ provide more useful information to users about your site, and what
+ they can expect to find there.</p>
+
+ <p><code class="module"><a href="./mod/mod_includes.html">mod_includes</a></code> and <code class="module"><a href="./mod/mod_negotiation.html">mod_negotiation</a></code>
+ must be enabled to use this feature.</p>
+
+ </div></div>
<div class="bottomlang">
<p><span>Available Languages: </span><a href="./en/custom-error.html" title="English"> en </a> |
<a href="./es/custom-error.html" hreflang="es" rel="alternate" title="Español"> es </a> |
Modified: httpd/httpd/trunk/docs/manual/custom-error.xml
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/manual/custom-error.xml?rev=922267&r1=922266&r2=922267&view=diff
==============================================================================
--- httpd/httpd/trunk/docs/manual/custom-error.xml (original)
+++ httpd/httpd/trunk/docs/manual/custom-error.xml Fri Mar 12 14:19:08 2010
@@ -25,142 +25,117 @@
<title>Custom Error Responses</title>
<summary>
- <p>Additional functionality allows webmasters to configure the response
- of Apache to some error or problem.</p>
- <p>Customizable responses can be defined to be activated in the event of
- a server detected error or problem.</p>
+ <p>Although the Apache HTTP Server provides generic error responses
+ in the event of 4xx or 5xx HTTP status codes, these responses are
+ rather stark, uninformative, and can be indimidating to site users.
+ You may wish to provide custom error responses which are either
+ friendlier, or in some language other than English, or perhaps which
+ are styled more in line with your site layout.</p>
+
+ <p>Customized error responses can be defined for any HTTP status
+ code designated as an error condition - that is, any 4xx or 5xx
+ status.</p>
+
+ <p>Additionally, a set of values are provided, so
+ that the error document can be customized further based on the
+ values of these variables, using <a href="howto/ssi.html">Server
+ Side Includes</a>. Or, you can have error conditions handled by a
+ cgi program, or other dynamic handler (PHP, mod_perl, etc) which
+ makes use of these variables.</p>
- <p>If a script crashes and produces a "500 Server Error" response,
- then this response can be replaced with either some friendlier text or by
- a redirection to another URL (local or external).</p>
</summary>
- <section id="behavior">
- <title>Behavior</title>
+ <section id="configuration"><title>Configuration</title>
- <section>
- <title>Old Behavior</title>
+ <p>Custom error documents are configured using the <directive
+ module="core">ErrorDocument</directive> directive.
+ <code>ErrorDocument</code>, which may be used in global,
+ virtualhost, or directory context. It may be used in .htaccess files
+ if <directive module="core">AllowOverride</directive> is set to
+ FileInfo.</p>
- <p>NCSA httpd 1.3 would return some boring old error/problem message
- which would often be meaningless to the user, and would provide no
- means of logging the symptoms which caused it.</p>
- </section>
+ <example>
+ ErrorDocument 500 "Sorry, our script crashed. Oh dear"<br />
+ ErrorDocument 500 /cgi-bin/crash-recover<br />
+ ErrorDocument 500 http://error.example.com/server_error.html<br />
+ ErrorDocument 404 /errors/not_found.html <br />
+ ErrorDocument 401 /subscription/how_to_subscribe.html
+ </example>
- <section>
- <title>New Behavior</title>
+ <p>The syntax of the <code>ErrorDocuemnt</code> directrive is:</p>
- <p>The server can be asked to:</p>
+ <example>
+ ErrorDocument <3-digit-code> <action>
+ </example>
- <ol>
- <li>Display some other text, instead of the NCSA hard coded
- messages, or</li>
+ <p>where the action can be one of:</p>
- <li>redirect to a local URL, or</li>
+ <ol>
+ <li>Text to be displayed. Wrap the text with quotes (").</li>
+ <li>A local URL to redirect to.</li>
+ <li>An external URL to redirect to.</li>
+ </ol>
+
+ <p>When redirecting to a local URL, additional environment variables
+ are set so that the response can be further customized. They are not sent to
+ external URLs.</p>
+
+ </section>
- <li>redirect to an external URL.</li>
- </ol>
+ <section id="variables"><title>Available Variables</title>
<p>Redirecting to another URL can be useful, but only if some
- information can be passed which can then be used to explain and/or log
- the error/problem more clearly.</p>
+ information can be passed which can then be used to explain or log
+ the error condition more clearly.</p>
- <p>To achieve this, Apache will define new CGI-like environment
- variables:</p>
+ <p>To achieve this, when the error redirect is sent, additional
+ environment variables will be set, which will be generated from
+ the headers provided to the original request by prepending
+ 'REDIRECT_' onto the original header name. This provides the error
+ document the context of the original request.</p>
+
+ <p>For example, you might recieve, in addition to more usual
+ environment variables, the following.</p>
<example>
- REDIRECT_HTTP_ACCEPT=*/*, image/gif, image/x-xbitmap,
- image/jpeg<br />
- REDIRECT_HTTP_USER_AGENT=Mozilla/1.1b2 (X11; I; HP-UX A.09.05
- 9000/712)<br />
- REDIRECT_PATH=.:/bin:/usr/local/bin:/etc<br />
+ REDIRECT_HTTP_ACCEPT=*/*, image/gif, image/jpeg, image/png<br />
+ REDIRECT_HTTP_USER_AGENT=Mozilla/5.0 Fedora/3.5.8-1.fc12 Firefox/3.5.8<br />
+ REDIRECT_PATH=.:/bin:/usr/local/bin:/sbin<br />
REDIRECT_QUERY_STRING=<br />
REDIRECT_REMOTE_ADDR=121.345.78.123<br />
- REDIRECT_REMOTE_HOST=ooh.ahhh.com<br />
- REDIRECT_SERVER_NAME=crash.bang.edu<br />
+ REDIRECT_REMOTE_HOST=client.example.com<br />
+ REDIRECT_SERVER_NAME=www.example.edu<br />
REDIRECT_SERVER_PORT=80<br />
- REDIRECT_SERVER_SOFTWARE=Apache/0.8.15<br />
+ REDIRECT_SERVER_SOFTWARE=Apache/2.2.15<br />
REDIRECT_URL=/cgi-bin/buggy.pl
</example>
- <p>Note the <code>REDIRECT_</code> prefix.</p>
+ <p><code>REDIRECT_</code> environment variables are created from
+ the environment variables which existed prior to the
+ redirect. They are renamed with a <code>REDIRECT_</code>
+ prefix, <em>i.e.</em>, <code>HTTP_USER_AGENT</code> becomes
+ <code>REDIRECT_HTTP_USER_AGENT</code>.</p>
+
+ <p><code>REDIRECT_URL</code>, <code>REDIRECT_STATUS</code>, and
+ <code>REDIRECT_QUERY_STRING</code> are guaranteed to be set, and
+ the other headers will be set only if they existed prior to the
+ error condition.</p>
- <p>At least <code>REDIRECT_URL</code> and
- <code>REDIRECT_QUERY_STRING</code> will be passed to the
- new URL (assuming it's a cgi-script or a cgi-include). The
- other variables will exist only if they existed prior to
- the error/problem. <strong>None</strong> of these will be
- set if your <directive module="core">ErrorDocument</directive> is an
+ <p><strong>None</strong> of these will be
+ set if the <directive module="core">ErrorDocument</directive> target is an
<em>external</em> redirect (anything starting with a
scheme name like <code>http:</code>, even if it refers to the same host
as the server).</p>
- </section>
</section>
- <section id="configuration">
- <title>Configuration</title>
-
- <p>Use of <directive module="core">ErrorDocument</directive> is enabled
- for .htaccess files when the
- <directive module="core">AllowOverride</directive> is set to FileInfo.</p>
-
- <p>Here are some examples...</p>
-
- <example>
- ErrorDocument 500 /cgi-bin/crash-recover <br />
- ErrorDocument 500 "Sorry, our script crashed. Oh dear" <br />
- ErrorDocument 500 http://xxx/ <br />
- ErrorDocument 404 /Lame_excuses/not_found.html <br />
- ErrorDocument 401 /Subscription/how_to_subscribe.html
- </example>
-
- <p>The syntax is,</p>
+ <section id="custom"><title>Customizing Error Responses</title>
- <example>
- ErrorDocument <3-digit-code> <action>
- </example>
-
- <p>where the action can be,</p>
-
- <ol>
- <li>Text to be displayed. Wrap the text with quotes (").</li>
-
- <li>An external URL to redirect to.</li>
-
- <li>A local URL to redirect to.</li>
- </ol>
- </section>
-
- <section id="custom">
- <title>Custom Error Responses and Redirects</title>
-
- <p>Apache's behavior to redirected URLs has been modified so
- that additional environment variables are available to a
- script/server-include.</p>
-
- <section>
- <title>Old behavior</title>
-
- <p>Standard CGI vars were made available to a script which
- has been redirected to. No indication of where the
- redirection came from was provided.</p>
- </section>
-
- <section>
- <title>New behavior</title>
-
- <p>A new batch of environment variables will be initialized
- for use by a script which has been redirected to. Each new
- variable will have the prefix <code>REDIRECT_</code>.
- <code>REDIRECT_</code> environment variables are created from
- the CGI environment variables which existed prior to the
- redirect, they are renamed with a <code>REDIRECT_</code>
- prefix, <em>i.e.</em>, <code>HTTP_USER_AGENT</code> becomes
- <code>REDIRECT_HTTP_USER_AGENT</code>. In addition to these
- new variables, Apache will define <code>REDIRECT_URL</code>
- and <code>REDIRECT_STATUS</code> to help the script trace its
- origin. Both the original URL and the URL being redirected to
- can be logged in the access log.</p>
+ <p>If you point your <code>ErrorDocument</code> to some variety of
+ dynamic handler such as a server-side include document, CGI
+ script, or some variety of other handler, you may wish to use the
+ available custom environent variables to customize this
+ response.</p>
<p>If the ErrorDocument specifies a local redirect to a CGI
script, the script should include a "<code>Status:</code>"
@@ -180,11 +155,45 @@
condition, such as <code>404 Not Found</code>, it can
use the specific code and error text instead.</p>
- <p>Note that the script <em>must</em> emit an appropriate
- <code>Status:</code> header (such as <code>302 Found</code>), if the
- response contains a <code>Location:</code> header (in order to issue a
- client side redirect). Otherwise the <code>Location:</code> header may
- have no effect.</p>
- </section>
+ <p>Note that if the response contains <code>Location:</code>
+ header (in order to issue a client-side redirect), the script
+ <em>must</em> emit an appropriate <code>Status:</code> header
+ (such as <code>302 Found</code>). Otherwise the
+ <code>Location:</code> header may have no effect.</p>
+
</section>
+
+ <section id="multi-lang"><title>Multi Language Customer Error Documents</title>
+
+ <p>Provided with your installation of the Apache HTTP Server is a
+ directory of custom error documents translated into 16 different
+ languages. There's also a configuration file in the
+ <code>conf/extra</code> configuration directory that can be included
+ to enable this feature.</p>
+
+ <p>In your server configuration file, you'll see a line such as:</p>
+
+ <example>
+ # Multi-language error messages<br />
+ #Include conf/extra/httpd-multilang-errordoc.conf
+ </example>
+
+ <p>Uncommenting this <code>Include</code> line will enable this
+ feature, and provide language-negotiated error messages, based on
+ the language preference set in the client browser.</p>
+
+ <p>Additionally, these documents contain various of the
+ <code>REDIRECT_</code> variables, so that additional information can
+ be provided to the end-user about what happened, and what they can
+ do now.</p>
+
+ <p>These documents can be customized to whatever degree you wish to
+ provide more useful information to users about your site, and what
+ they can expect to find there.</p>
+
+ <p><module>mod_includes</module> and <module>mod_negotiation</module>
+ must be enabled to use this feature.</p>
+
+ </section>
+
</manualpage>