public function serialize(DOMElement $ir)
	{
		$this->xpath  = new DOMXPath($ir->ownerDocument);
		$this->isVoid = [];
		foreach ($this->xpath->query('//element') as $element)
		{
			$this->isVoid[$element->getAttribute('id')] = $element->getAttribute('void');
		}

		return $this->serializeChildren($ir);
	}