Backport 418360 (per-directory rewrites clarification)

        </li>

      </ul>

<note><title>Note: Enabling rewrites in per-directory context</title>

 To enable the rewrite engine

          for per-directory configuration files you need to set

          ``<code>RewriteEngine On</code>'' in these files

          <strong>and</strong> ``<code>Options

          FollowSymLinks</code>'' must be enabled. If your

          administrator has disabled override of

          <code>FollowSymLinks</code> for a user's directory, then

          you cannot use the rewrite engine. This restriction is

          required for security reasons.

</note>

<note><title>Note: Pattern matching in per-directory context</title> 

	Never forget that <em>Pattern</em> is

applied to a complete URL in per-server configuration

files. <strong>However, in per-directory configuration files, the

<note><title>Per-directory Rewrites</title>

<p>The rewrite engine may be used in <a

href="../howto/htaccess.html">.htaccess</a> files.  To enable the

rewrite engine for these files you need to set

"<code>RewriteEngine On</code>" <strong>and</strong>

"<code>Options FollowSymLinks</code>" must be enabled. If your

administrator has disabled override of <code>FollowSymLinks</code> for

a user's directory, then you cannot use the rewrite engine. This

restriction is required for security reasons.</p>

<p>When using the rewrite engine in <code>.htaccess</code> files the

per-directory prefix (which always is the same for a specific

directory) is automatically <em>removed</em> for the pattern matching

and automatically <em>added</em> after the substitution has been

done.</strong> This feature is essential for many sorts of rewriting - 

without this, you would always have to match the parent

directory, which is not always possible.

            <p>There is one exception: If a substitution string

            starts with ``<code>http://</code>'', then the directory

            prefix will <strong>not</strong> be added ,and an

            external redirect (or proxy throughput, if using flag

            <strong>P</strong>) is forced!</p>

done. This feature is essential for many sorts of rewriting; without

this, you would always have to match the parent directory, which is

not always possible.  There is one exception: If a substitution string

starts with <code>http://</code>, then the directory prefix will

<strong>not</strong> be added, and an external redirect (or proxy

throughput, if using flag <strong>P</strong>) is forced.  See the

<directive module="mod_rewrite">RewriteBase</directive> directive for

more information.</p>

<p>The rewrite engine may also be used in <directive type="section"

module="core">Directory</directive> sections with the same

prefix-matching rules as would be applied to <code>.htaccess</code>

files.  It is usually simpler, however, to avoid the prefix substitution

complication by putting the rewrite rules in the main server or

virtual host context, rather than in a <directive type="section"

module="core">Directory</directive> section.</p>

<p>Although rewrite rules are syntactically permitted in <directive

type="section" module="core">Location</directive> sections, this

should never be necessary and is unsupported.</p>

</note>

<note><title>Note: Substitution of Absolute URLs</title>