Security Warning Take care when constructing the target URL of the rule, considering the security impact from allowing the client influence over the set of URLs to which your server will act as a proxy. Also note that we removed the question mark?
Note that some environment variables may be set after the rule is run, thus unsetting what you have set. It must be at least two parts separated by a dot.
RewriteRule ".? Useful when the backreference will be used in the path component rather than the query string. To decide whether or not to use this rule: if you prefix URLs with CGI-scripts, to force them to be processed by the CGI-script, it's likely that you will run into problems or significant overhead on sub-requests.
Then, that environment variable is used to exclude those requests from the access log.
When the replacement URI contains a query string, the default behavior of RewriteRule is to discard the existing query string, and replace it with the newly generated one. A value of 0 indicates that the cookie will persist only for the current browser session.