private function get_values($scheme) {
		$resourceurl = $this->get_resource_url();
		if (!$resourceurl) {
			return array();
		}
		
		$info = $this->data[$resourceurl];

		if (!isset($info[$scheme])) {
			return array();
		}

		$values = array();
		foreach ($info[$scheme] as $k => $v) {
			$values[$k] = $v['value'];
		}
		return $values;
	}