UCP600 (Art.2) ：Credit means any arrangement, however named or described, that is irrevocable and thereby constitutes a definite undertaking of the issuing bank to honour a complying presentation.请根据英文填空。信用证是指一项（1）的安排，无论其名称或描述如何，该项安排构成开证行对（2）予以（3）的确定承诺。