Sync with the much better explanation and example in trunk.

    in your filesystem, and would otherwise return HTTP 404 (Not Found).

    For example</p>

    <example>

        <code>FallbackResource default.php</code>

        <code>FallbackResource /not-404.php</code>

    </example>

    <p>will cause requests for non-existent files to be handled by

    <code>default.php</code>, while requests for files that exist

    <code>not-404.php</code>, while requests for files that exist

    are unaffected.</p>

    <p>It is frequently desirable to have a single file or resource

    handle all requests to a particular directory, except those requests

    that correspond to an existing file or script. This is often

    referred to as a 'front controller.'</p>

    <p>In earlier versions of httpd, this effect typically required

    <module>mod_rewrite</module>, and the use of the <code>-f</code> and

    <code>-d</code> tests for file and directory existence. This now

    requires only one line of configuration.</p>

    <example>

        <code>FallbackResource /index.php</code>

    </example>

    <p>Existing files, such as images, css files, and so on, will be

    served normally.</p>

    <p>In a sub-URI, such as <em>http://example.com/blog/</em> this

    <em>sub-URI</em> has to be supplied as <var>local-url</var>:</p>

    <example>

         <code>

             &lt;Directory /web/example.com/htdocs/blog&gt;<br />

	     <indent>

                  FallbackResource /blog/index.php<br />

             </indent>

             </Directory>

         </code>

    </example>

</usage>

</directivesynopsis>