Shitokan, also known as Shitokan-sei system, is a term that refers to the fact that core officials of government offices were comprised of people of four ranks under the Ritsuryo system (a system of centralized government under the Ritsuryo code).
四等官（しとうかん）または四等官制（-せい）は、律令制において各官司の中核職員が4等級で構成されていたことを表す用語。