protected function &GetOrderByFilterList()
    {
        $aFilterIds = $this->oModuleConf->GetMLTIdList('shop_module_articlelist_orderby');
        $oList = TdbShopModuleArticlelistOrderbyList::GetListForIds($aFilterIds);
        $oList->bAllowItemCache = true;
        // fill item cache
        $i = 0;
        while ($oItem = $oList->Next()) {
            ++$i;
        }
        $oList->GoToStart();

        return $oList;
    }