Under the Ritsuryo system, when the term of kokushi (provincial governor) expired, a document called Geyujo (discharge certificate) was delivered from a predecessor to a successor as evidence to prove that the handing over of a job was carried out without any problems.
律令制の下では、国司の任期が満了したとき、事務引継ぎが問題なく行われた証として、後任国司から前任国司へ解由状（げゆじょう）という文書が交付されていた。