The court of the middle ages was maintained by establishing Yusokukojitu (precedent cases and stories about court protocol) of Chogi as a Kagaku and the various aristocratic families became in charge of it as Kashoku and if the family had no successor, such families were reestablished by taking members in by adoption.
中世の朝廷は朝儀に関する有職故実を家学化して、公家の諸家がそれを家職として分掌することで維持され、万が一断絶に至った場合にはそうした家を養子縁組によって再興・継続させる方針が採られていった。