title: What file types does header("Content-Encoding: gzip") support?
body: <p>I'm using this snippet:</p>
  
  <pre><code>// ... snip
  
  header("Content-Encoding: gzip");
  include some_file;
  
  // ... snip
  </code></pre>
  
  <p>to serve zipped content.</p>
  
  <p>What types of encoding can I serve this way.  i.e what can i put in for some_file?</p>