public static function get_item_ratings_parameters() {
        return new external_function_parameters (
            array(
                'contextlevel'  => new external_value(PARAM_ALPHA, 'context level: course, module, user, etc...'),
                'instanceid'    => new external_value(PARAM_INT, 'the instance id of item associated with the context level'),
                'component'     => new external_value(PARAM_COMPONENT, 'component'),
                'ratingarea'    => new external_value(PARAM_AREA, 'rating area'),
                'itemid'        => new external_value(PARAM_INT, 'associated id'),
                'scaleid'       => new external_value(PARAM_INT, 'scale id'),
                'sort'          => new external_value(PARAM_ALPHA, 'sort order (firstname, rating or timemodified)')
            )
        );
    }