What are the internal officials and external officials recorded in "Selected Classics II"?

During the Wei and Jin Dynasties, officials responsible for selecting and appointing officials were divided into internal officials and external officials. "General Canon Selection II" contains: "The Jin Dynasty is based on Wei Jiujing, and the internal officials are: Shangshu of the official department and Chang Shi of Situ Zuo; Foreigner: There are Dazhongzheng in the state and Xiaozhongzheng in the county. If the official department chooses it, it will collect its residence and father and ancestors from Zhongzheng. " If the official department needs to choose an official, it will be recommended by Zhong Zheng of the county, and the details of the first person in each product will be reported to the official department, which will award the position.