The legislation of Kyakushiki was developed over the ninth and the tenth century, and three major Kyakushiki (Sandai Kyakushiki) which were Kounin Kyakushiki, Jyougan Kyakushiki, and Engi Kyakushiki were compiled and edited.
9世紀から10世紀にかけて格式の法制整備が進み、弘仁格式・貞観格式・延喜格式（三代格式）が編纂された。