protected function toString_attributes() {
		$s = '';
		foreach($this->attributes as $a => $v) {
			$s .= ' '.$a;
			if ((!$this->attribute_shorttag) || ($v !== $a)) {
				$quote = (strpos($v, '"') === false) ? '"' : "'";
				$s .= '='.$quote.$v.$quote;
			}
		}
		return $s;
	}