diff --git a/ext/rating/main.php b/ext/rating/main.php
index 714c96a5..be54cdb4 100644
--- a/ext/rating/main.php
+++ b/ext/rating/main.php
@@ -5,6 +5,18 @@
  * Link: http://code.shishnet.org/shimmie2/
  * License: GPLv2
  * Description: Allow users to rate images "safe", "questionable" or "explicit"
+ * Documentation:
+ *  This shimmie extension provides filter:
+ *  <ul>
+ *    <li>rating = (safe|questionable|explicit|unknown)
+ *      <ul>
+ *        <li>rating=s -- safe images
+ *        <li>rating=q -- questionable images
+ *        <li>rating=e -- explicit images
+ *        <li>rating=u -- Unknown rating
+ *        <li>rating=sq -- safe and questionable images
+ *      </ul>
+ *  </ul>
  */
 
 class RatingSetEvent extends Event {