title: Htaccess setenvif header defined
body: <p>I was trying to make correct ajax redirect, by apache. 
  All request are going to index.php where they are routing, 
  but i want to filer ajax request by defined header, 
  and check it before php - via htaccess, and redirect to ajax.php.
  I was reading manuals and test some days before, but this simple lang. is not so simple :(
  Htaccess is looking like that:</p>
  
  <pre><code>Options +FollowSymlinks
  DirectoryIndex index.php
  RewriteEngine On
  RewriteBase /
  Options +FollowSymlinks
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ test/over/index.php?do=$1 [L,QSA]
  </code></pre>