public static function _appendToChain($aExtend)
 {
     // if the chain is still empty and "original" chain is needed
     if (self::$_blOriginal && !count(self::$_aChain)) {
         self::$_aChain = (array) modConfig::getInstance()->getConfigParam("aModules");
     }
     // addping the "extend" chain to the main chain
     foreach ($aExtend as $sParent => $sExtends) {
         if (isset(self::$_aChain[$sParent])) {
             $sExtends = trim(self::$_aChain[$sParent], "& ") . "&" . trim($sExtends, "& ");
         }
         self::$_aChain[$sParent] = $sExtends;
     }
 }