protected function extractSignature($elementString)
	{
		$match = array();

		$regexp = '@\{/?(' . $this->getSignaturesRegexp() . ').*?/?\}@ims';

		preg_match($regexp, $elementString, $match);

		if (empty($match[1])) {
			return null;
			//throw new Exception\RuntimeException('Could not extract signature from "' . $elementString . '"');
		}
		
		return $match[1];
	}