--- file.inc	2010-12-20 10:49:26.144407178 -0800
+++ /tmp/file.inc	2011-01-03 17:37:55.789450065 -0800
@@ -658,7 +658,7 @@
  * @param $file
  *   A Drupal file object.
  * @param $extensions
- *   A string with a space separated
+ *   A string with a space separated list of allowed file extensions, not including the period. i.e 'jpg gif png'.
  * @return
  *   An array. If the file extension is not allowed, it will contain an error message.
  */