《笑林广记·古艳部》
妾问为什么要这样写？丈夫说： 在一起做官的人写帖子，都用这样的称呼，这是官场的惯例。 
妾问其义如何，夫曰： 同僚写帖，皆用此称呼，做官府之例耳。 
The concubine asked why it should be written this way. The husband said, "Officials who work together write invitations this way. It's a custom in the officialdom."