Shitokan-sei system was based on Chokan (minister), Nitokan (second-rank official), Santokan (third-rank official) and Shitokan (fourth-rank official), and their respective responsibilities were determined by Ryo (administrative code).
四等官制は、長官・二等官・三等官・四等官の4等級から構成されており、令において、それぞれの分掌事務が定められている。