Every government official is in some form of hierarchical relationship with other officials under Ritsuryo law, and "I" (移) was used to exchange documents between officials who are not in hierarchical relationships with each other.
律令法では、各官司は必ず所管－被管の上下関係を有しているが、自己所管－被管関係の枠外にある官司との文書のやりとりの際にこれを用いた。