Backend\Core\Engine\DataGrid::setSortingOptions PHP Method

    private function setSortingOptions()
    {
        // default URL
        if (BackendModel::getContainer()->get('url')) {
            $this->setURL(BackendModel::createURLForAction(null, null, null, array('offset' => '[offset]', 'order' => '[order]', 'sort' => '[sort]'), false));
        }
        // sorting labels
        $this->setSortingLabels(BackendLanguage::lbl('SortAscending'), BackendLanguage::lbl('SortedAscending'), BackendLanguage::lbl('SortDescending'), BackendLanguage::lbl('SortedDescending'));
    }