public function get_coords_interpreter_error() {
        if ($this->error) {
            $a = new stdClass();
            $a->shape = self::human_readable_name(true);
            $a->coordsstring = self::human_readable_coords_format();
            return get_string('formerror_'.$this->error, 'qtype_ddmarker', $a);
        } else {
            return false;
        }
    }