Index: src/wp-admin/network.php
===================================================================
--- src/wp-admin/network.php	(revision 25618)
+++ src/wp-admin/network.php	(working copy)
@@ -65,6 +65,13 @@
  */
 function allow_subdirectory_install() {
 	global $wpdb;
+        /**
+         * Filter enabling subdirectory installs.
+         * 
+         * @since 3.0.0
+         * 
+         * @param boolean Whether or not to allow subdirectory installs. Defaults to false.
+         */
 	if ( apply_filters( 'allow_subdirectory_install', false ) )
 		return true;