It is stipulated in "Yoro-ryo" (Yoro Code) and "Taiho-ryo" (Taiho Code) that in the case of zoi due to death at war, Oni (the automatic promotion of the persons at the age of 21, whose parents are from Imperial Prince to the fifth rank, or whose grandparents are upper than third rank) to his children and grandchildren would be equal to the rank he held while he was alive, and in other cases, Oni was usually with a rank, one lower to the rank which would normally be bestowed upon.
『養老令』『大宝令』では、戦死による贈位の場合、その子・孫への蔭位は、生前の帯位と同等とし、それ以外の贈位の場合、蔭位は通常の位階より一階降して授けることとされた。