public function checkFragment($fragment = null)
    {
        if ($fragment === null) {
            $fragment = $this->fragment;
        }

        if (strlen($fragment) == 0) {
            return true;
        }

        $pattern = "/^" . $this->regex["uric"] . "*$/";
        $status = @preg_match($pattern, $fragment);

        if ($status === false) {
            throw new Ts3Exception("URI fragment validation failed");
        }

        return ($status == 1);
    }