写信的原则（Writing Principles）已从原来的3个“C”（Conciseness, Clearness, Courtesy）发展到目前的７个“C”：Completeness, Clearness, Concreteness, Conciseness, Correctness, Courtesy, Consideration

实例：

Dear Sirs,

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.

关于你们四月九日函，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。

来源：新东方在线