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>