This clean credit will be automatically extended for a further year, without written amendment, on the first day of January of every future year from the commencement date, so that it is always valid for a minimum period of four years unless, at least thirty days prior to the 31st day of December of the first year of the current validity period, notice is given in writing, sent by registered mail, that this clean credit will not be extended beyond the current expiry date. Such credits are commonly called: (1)(  ) Evergreen credits. (2)(  ) Revolving credits. (3)(  ) Transferable credits.