expand on ProxyPassReverse args
split up the two arguments into their own paragraphs
try to reinforce that the 2nd arg has to match the response
hedaer, and what the first one is used for.
@@ -1559,9 +1559,25 @@ proxied server</description>
match the proxy, you must load and enable <module>mod_proxy_html</module>.
</p>
- <p><var>path</var> is the name of a local virtual path; <var>url</var> is a
- partial URL for the remote server. These parameters are used the same way as
- for the <directive module="mod_proxy">ProxyPass</directive> directive.</p>
+ <p><var>path</var> is the name of a local virtual path. It is combined
+ with the requests scheme, host, and port to form the replacement
+ prefix of the affected response header.
+ This parameter is usually the same as the first parameter of the
+ <directive module="mod_proxy">ProxyPass</directive> directive.
+ </p>
+
+ <p><var>url</var> is a partial URL for the remote server. When the remote
+ server sends the specifically mentioned headers beginning with this partial
+ URL, the prefix from the remote server is replaced with a prefix that
+ points to the reverse proxy.
+ This parameter is usually the same as the second parameter of the
+ <directive module="mod_proxy">ProxyPass</directive> directive, but it may
+ differ if the remote server uses a different scheme, host, port, or path
+ in the affected headers. In configurations with
+ <directive module="mod_proxy">ProxyPreserveHost</directive>, the hostname
+ in the partial URL may already be the hostname of the reverse proxy, which
+ will prevent the matching and replacement done by this directive.
+ </p>
<p>For example, suppose the local server has address
<code>http://example.com/</code>; then</p>
