https://www.php.net/manual/de/domnode.lookupprefix.php
PHP: DOMNode::lookupPrefix - Manual
Gets the namespace prefix of the node based on the namespace URI
phpmanual
https://www.php.net/manual/en/domnode.lookupprefix.php
PHP: DOMNode::lookupPrefix - Manual
Gets the namespace prefix of the node based on the namespace URI
phpmanual