Kugen were considered to be valid evidence with a recognized legal effect guaranteeing the ownership right to assets, including land; therefore, they were remained valid across generations, and were passed on when any legal changes occurred.
公験は所有権をはじめとした財産や権利を保証する法的な効力が認められる有力な証明とされていたことから、代を重ねた保証され、法的変動の際には同時に公験も譲渡された。