$dom = new DOMDocument('1.0', 'utf-8');

$element = $dom->createElement('test', 'root');

$dom->appendChild($element);

$element->setAttribute("id", 123);
$element->setIdAttribute("id", true);

$node = $element->getAttributeNode("id");
echo $node->isId(), "\n";

$element->setIdAttribute("id", true);
echo $node->isId(), "\n";

1

	if (is_id == 1 && attrp->atype != XML_ATTRIBUTE_ID) {
		xmlChar *id_val;

		id_val = xmlNodeListGetString(attrp->doc, attrp->children, 1);
		if (id_val != NULL) {
			xmlAddID(NULL, attrp->doc, id_val, attrp);
			xmlFree(id_val);
		}
	} else {
		if (attrp->atype == XML_ATTRIBUTE_ID) {
			xmlRemoveID(attrp->doc, attrp);
			attrp->atype = 0;
		}
	}