使用带有一些空文件结构的'SimpleXMLElement'生成XML？

$sitemap .= "  " . '<orders>' . "\n" .
    "\t" . '<idKlant>' . $id. '</idKlant>' .
    "\n\t" . '<emptyfield></emptyfield>' .
     "\n\t" . '<date>' . $verzenddatum . '</date>' . //remaining to get
    "\n  " . '</orders>' . "\n";
$sitemap .= "  " . '<orders>' . "\n" .
    "\t"