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.
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。