写信的原则（Writing Principles）已从原来的3（Conciseness, Clearness, Courtesy）发展到目前的７个"Ｃ"： Completeness, Clearness, Concreteness, Conciseness, Correctness, Courtesy, Consideration)
实例
Dear Sirs,
Copper Wire
With reference to your letter of April 9, we are pleased to accept your offer of 100 tons of Copper Wire as per your Offer Sheet No.8/070/02B. Please go ahead and apply for your Export Licence. As soon as we are informed of the number of the Export Licence we will open the L/C by cable.
(信的本文汉译)：
关于你们四月九日涵，我们高兴地接受你们第８／０７０／０２Ｂ号报盘单所报１００吨紫色铜丝。请着手办理申请出口许可证。 一经接到出口许可证号码的通知，当即电开信用证。