public function get_submitted_data($postdata = null) {
        $submitteddata = $this->get_expected_data(
                $this->behaviour->get_expected_data(), $postdata, '-');

        $expected = $this->behaviour->get_expected_qt_data();
        $this->check_qt_var_name_restrictions($expected);

        if ($expected === self::USE_RAW_DATA) {
            $submitteddata += $this->get_all_submitted_qt_vars($postdata);
        } else {
            $submitteddata += $this->get_expected_data($expected, $postdata, '');
        }
        return $submitteddata;
    }