private function writeNumFmt(XMLWriter $objWriter, NumberFormat $pNumberFormat, $pId = 0)
    {
        // Translate formatcode
        $formatCode = $pNumberFormat->getFormatCode();

        // numFmt
        if ($formatCode !== null) {
            $objWriter->startElement('numFmt');
            $objWriter->writeAttribute('numFmtId', ($pId + 164));
            $objWriter->writeAttribute('formatCode', $formatCode);
            $objWriter->endElement();
        }
    }