(1)授权书；全权证书

(2)证明书
用以表明某人值得信赖的文件。

(3)(国际法)国书
用以证明大使及外交代表身份的证件，其内容主要介绍其品德才能可以依赖等，同时表示派遣国的国家元首或外交部长对发展两国关系的良好愿意。

• Clerks of Records and Writs
• Clerks of Seats
• Clerks of the Chancery
• clerks of the general sessions of the peace
• Clerks of the Privy Seal
• on a lay
• on all fours
• onanism
• on a passage
• on arrival
• O.N.B.
• on board
• onboard bill (of lading)
• on call
• on call note
• Once a highway, always a highway.
• Once a mortgage, always a mortgage.
• Once an Englishman always an Englishman.
• once a week for four successive weeks
• once in jeopardy
• on commission
• on condition
• oncunne
• on default
• on demand