The first part in question in the Empress Gensho's edict upon enthronement, and the Emperor Shomu's edict upon enthronement as well as his edict upon abdication, referred to Fukai-no-Joten/ Fukaijoten as the base of authority that justifies the Emperor Shomu's succession of the Imperial Throne.
元正天皇の即位詔の第一の箇所と、聖武天皇即位と譲位の詔では、不改常典が聖武天皇の皇位継承の根拠とされている。