What does the idiom three sets of eight seats mean?

Santai: The general name of Shangshu, Shi Yu and philosophers in Han Dynasty. Shangshu is the "middle platform", the suggestion is the "constitutional platform", and the admirer is the "outer platform", which are collectively called "three platforms". Eight seats: 1, also called "eight seats". Eight kinds of senior officials of the central government in feudal times. Different dynasties have different systems and different meanings. In the Eastern Han Dynasty, the ministers of the Six Dynasties of Cao, together with the ministers and servants, became "eight seats"; In the Wei, Southern Song and Qi Dynasties, five Cao Shangshu and two servants were the "eight seats"; During the Sui and Tang Dynasties, six ministers, left and right servants and orders were regarded as "eight seats". In the Qing dynasty, it was used as the title of six ministers. Later literary works mostly refer to senior officials such as Shangshu.

It is commonly said that the person sitting in the sedan chair carried by eight people is "eight seats". So three sets of eight seats generally refer to senior officials.