definite undertaking meaning in English

明确承诺
确定性承担义务
确定性的承担义务

Confirmation means a definite undertaking of the confirming bank , in addition to that of the issuing bank , to honour or negotiate a complying presentation
保兑意指保兑行在开证行之外对于相符提示做出兑付或议付的确定承诺。
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
信用证意指一项约定，无论其如何命名或描述，该约定不可撤销并因此构成开证行对于相符提示予以兑付的确定承诺。