It can be said to be an expression produced by the energy of the time during a period from the reign of Emperor Tenmu to Jito, when the Japanese nation was being established under the ritsuryo codes, and also taking into account the limitations of the period in regard to expressions.
天武朝から持統朝という律令国家制定期におけるエネルギーの生み出した、時代に規制される表現であるといえる。