Index: wp-includes/taxonomy.php
===================================================================
--- wp-includes/taxonomy.php	(revision 18125)
+++ wp-includes/taxonomy.php	(working copy)
@@ -1129,6 +1129,11 @@
  * The 'parent' argument is different from 'child_of' in that a term X is considered a 'parent'
  * of term Y only if term X is the father of term Y, not its grandfather or great-grandfather, etc.
  *
+ * The 'cache_domain' argument enables a unique cache key to be produced when this query is stored
+ * in object cache. For instance, if you are using one of this function's filters to modify the 
+ * query (such as 'terms_clauses'), setting 'cache_domain' to a unique value will not overwrite
+ * the cache for similar queries. Default value is 'core'.
+ *
  * @package WordPress
  * @subpackage Taxonomy
  * @since 2.3.0
@@ -1161,7 +1166,7 @@
 		'hide_empty' => true, 'exclude' => array(), 'exclude_tree' => array(), 'include' => array(),
 		'number' => '', 'fields' => 'all', 'slug' => '', 'parent' => '',
 		'hierarchical' => true, 'child_of' => 0, 'get' => '', 'name__like' => '',
-		'pad_counts' => false, 'offset' => '', 'search' => '');
+		'pad_counts' => false, 'offset' => '', 'search' => '', 'cache_domain' => 'core' );
 	$args = wp_parse_args( $args, $defaults );
 	$args['number'] = absint( $args['number'] );
 	$args['offset'] = absint( $args['offset'] );