public static function get_strings_parameters() {
        return new external_function_parameters(
            array('strings' => new external_multiple_structure (
                    new external_single_structure (array(
                        'stringid' => new external_value(PARAM_STRINGID, 'string identifier'),
                        'component' => new external_value(PARAM_COMPONENT, 'component', VALUE_DEFAULT, 'moodle'),
                        'lang' => new external_value(PARAM_LANG, 'lang', VALUE_DEFAULT, null),
                        'stringparams' => new external_multiple_structure (
                            new external_single_structure(array(
                                'name' => new external_value(PARAM_ALPHANUMEXT, 'param name
                                    - if the string expect only one $a parameter then don\'t send this field, just send the value.', VALUE_OPTIONAL),
                                'value' => new external_value(PARAM_RAW, 'param value'))),
                                'the definition of a string param (i.e. {$a->name})', VALUE_DEFAULT, array()
                        ))
                    )
                )
            )
        );
    }