In other words, this suggests that in some cases, documents written by Moritoki or his Kao could guarantee equal authenticity as those of Yoritomo and of OE no Hiromoto, the head of Mandokoro.
つまり、盛時の書面あるいは花押が場合によっては頼朝や政所の長である大江広元の代わりになり得た事を示している。