public static function getBannedNamespaceIDs()
 {
     if (self::$banned_NS_IDs !== false) {
         return self::$banned_NS_IDs;
     }
     self::$banned_NS_IDs = array();
     foreach (self::$banned_NS_names as $ns_name) {
         self::$banned_NS_IDs[] = self::getNamespaceIDfromName($ns_name);
     }
     return self::$banned_NS_IDs;
 }