diff --git includes/form.inc includes/form.inc
index b639fa6..a2ac1a1 100644
--- includes/form.inc
+++ includes/form.inc
@@ -2621,9 +2621,20 @@ function form_get_options($element, $key) {
  *
  * @param $variables
  *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
- *     Properties used: #attributes, #children, #collapsed, #collapsible,
- *     #description, #id, #title, #value.
+ *   - element: An associative array containing:
+ *     - #attributes: An array of HTML attributes of the fieldset tag.
+ *     - #children: A string to use as the body of the fieldset.
+ *     - #collapsed: (optional) Boolean whether the fieldset body is initially
+ *       collapsed. In a collapsed fieldset, the body is hidden, and only the
+ *       title is visible. Defaults to FALSE.
+ *     - #collapsible: (optional) Boolean whether the fieldset body may be
+ *       collapsed (hidden) or expanded (shown) by clicking on the fieldset
+ *       title. Defaults to FALSE.
+ *     - #description: (optional) A string to insert before the #children text
+ *     - #id: (optional) A string to use as the ID attribute.
+ *     - #title: (optional) A string to use as the fieldset title.  If #collapsible
+ *       is TRUE, clicking on the title toggles whether the fieldset is collapsed.
+ *     - #value: (optional) A string to insert after the #children text.
  *
  * @ingroup themeable
  */