In response to this, Hiroshi KOZEN explained that evidently pairs were made, as the titles of the volume corresponded to each other such as East against West, and North against South (particularly the volumes of East and West were noticeable because they had small prefaces in the beginning), and concerning the format, in the volumes of East and West Kukai selected each family's comments on his own discretion, while in the volumes of South and North they were cited as they were.
これに対して興膳宏は、東・西、と北・南で巻題の命名に対応関係が見られること（とくに東・西の巻ではそれぞれ巻頭に小序が付されていてそれが顕著である）、また体裁の面でも東・西の巻が諸家の論を空海自身の裁量で取捨しているのに対し、南・北の巻ではそのままの形で引用されていることが多いなど、対になっているのは明らかだとしている。