Understanding apache RewriteLog

I'd like to understand the output from RewriteLog in apache2. I have something like ...... (3) applying pattern '^/img(.*)' to uri '/api/marker/2' ...... (3) applying pattern '^/img/imagecache/(.+)' to uri '/api/marker/2' ..... (1) pass through /api/marker/2 .... . (3) [perdir /some/path] add path info postfix: /some/path/marker -> /some/path/marker/2 .......(3) [perdir /some/path] strip per-dir prefix: /some/path/marker/2 -> marker/2 Those things in brackets (Example (1),(2) etc..., the key phrases "pass through" "applying pattern" "perdir" prefix/postfix etc. I don't see nothing in manual regarding this.