Comparing the usage of Chinese characters in Kasen-Ōrai, the Japanized Chinese written in the twelfth century, with that of Kōzanjibon-Ko-Ōrai composed in almost the same period, I caught the following results:
1) It is a general principle that we inscribe one Japanese word by the characters of the stereotyped kind.
2) Even when we inscribe one Japanese word by more than two kinds of Chinese characters, both the kind and inscription are stationary.