title: What are the different URL parameters that Facebook will append to an Action URL? Values? Format?
body: <p>When a user clicks on an action that my application publishes to their wall I see the following URL parameters appended to the URL in my referral logs:</p>
  
  <ul>
  <li>fb_action_ids</li>
  <li>fb_action_types</li>
  <li>fb_source</li>
  </ul>
  
  <p>Is there documentation that describes the format of these URL parameters?  If any of these parameters has a fixed value set what are the possible values? Are there additional parameters that are not listed here? </p>