if (!empty($_SERVER['HTTP_IF_MODIFIED_SINCE']) && ($nModified == strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE'])) && !empty($_SERVER['SERVER_PROTOCOL'])) {
            header('Last-Modified: ' . gmdate('D, d M Y H:i:s', $nModified) . ' GMT');
            header($_SERVER['SERVER_PROTOCOL'] . ' 304 Not Modified');
            exit;
        }