They should have been independently established as Shiki, Ryo, and Tsukasa (also known as Shi), however, the number of officials in this category was too small to do so, as a result, Honkan was established.
本来は職(律令制)・寮(律令制)・司として独立させるべきであるがそれには規模が小さいためこのような形態となった。