《南史·列传·卷七十七》
天下的文书户口，都把副本归中书省，他们谋事机密，外人不知，俨然有如尚书省的外司。
天下文簿板籍，入副其省，万机严秘，有如尚书外司。
Copies of all the documents and registers in the world were submitted to the Central Secretariat, and they planned in secrecy and were not known to outsiders, just like an external department of the Secretariat.