synch up with trunk for the first half of RewriteRule:

      <p><a id="patterns" name="patterns"><em>Pattern</em></a> is

      a perl compatible <a id="regexp" name="regexp">regular

      expression</a>. On the first RewriteRule it is applied to the

      expression</a>. On the first RewriteRule it is applied to the (%-encoded)

      <a href="./directive-dict.html#Syntax">URL-path</a> of the request;

      subsequent patterns are applied to the output of the last matched

      RewriteRule.</p>

<note><title>What is matched?</title>

      <p>The <em>Pattern</em> will initially be matched against the part of the

      URL after the hostname and port, and before the query string. If you wish

      to match against the hostname, port, or query string, use a

      <p>In <directive module="core">VirtualHost</directive> context, 

      The <em>Pattern</em> will initially be matched against the part of the

      URL after the hostname and port, and before the query string (e.g. "/app1/index.html").</p>

      <p>In <directive module="core">Directory</directive> and htaccess context,

      the <em>Pattern</em> will initially be matched against the  

      <em>filesystem</em> path, after removing the prefix that lead the server

      to the current <directive>RewriteRule</directive> (e.g. "app1/index.html" 

      or "index.html" depending on where the directives are defined).</p>

      <p>If you wish to match against the hostname, port, or query string, use a

      <directive module="mod_rewrite">RewriteCond</directive> with the

      <code>%{HTTP_HOST}</code>, <code>%{SERVER_PORT}</code>, or

      <code>%{QUERY_STRING}</code> variables respectively.</p>

</note>

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

<ul>

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

href="../howto/htaccess.html">.htaccess</a> files in <directive type="section"

module="core">Directory</directive> sections, with some additional

complexity.</li>

<li>To enable the rewrite engine in this context, 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.</li>

<li>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 RewriteRule pattern matching

and automatically <em>added</em> after any relative (not starting with a

slash or protocol name) substitution encounters the end of a rule set.  

See the <directive module="mod_rewrite">RewriteBase</directive> 

directive for more information regarding what prefix will be added back to 

relative substutions.</li>

<li> If you wish to match against the full URL-path in a per-directory 

(htaccess) RewriteRule, use the <code>%{REQUEST_URI}</code> variable in

a <directive>RewriteCond</directive>.</li>

<li>The removed prefix always ends with a slash, meaning the matching occurs against a string which

<em>never</em> has a leading slash.  Therefore, A <em>Pattern</em> with <code>^/</code> never

matches in per-directory context.</li>

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

type="section" module="core">Location</directive> and <directive

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

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

</ul>

</note>

      <p>For some hints on <glossary ref="regex">regular

      expressions</glossary>, see

      the <a href="../rewrite/rewrite_intro.html#regex">mod_rewrite

      the <a href="../rewrite/intro.html#regex">mod_rewrite

      Introduction</a>.</p>

      <p>In mod_rewrite, the NOT character

      it is easier to match the negative pattern, or as a last

      default rule.</p>

<note><title>Note</title>

When using the NOT character to negate a pattern, you cannot include 

grouped wildcard parts in that pattern. This is because, when the 

<p> This expansion does not occur when the <em>PT</em>

flag is used on the <directive module="mod_rewrite">RewriteRule</directive>

directive.</p>

</note>

<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. 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>

     <p>Here are all possible substitution combinations and their