The feature in Shoten "声点" used by Tendaishu-Jimonha "天台宗寺門派" at the Heian era was to have used △. △ was what Kyoso "慶祚 (955~1020)" of Mii-dera Temple invented it in around 1000 in the Christian era. Only △ was used for the material of the 12th century.
In Material of the Nishihakaten "西墓点" of Tendaishu-Jimonha "天台宗寺門派" in the middle of the Heian era, △ was not used.
After 1000 in the Christian era, the system of Shoten "声点" including the apprentice of Kyoso "慶祚" is many kinds and various. Before Kyoso "慶祚" invents △, the apprentice shows that his linguistic system had been acquired. Moreover, Japanese reading language unfixation, it is shown that there was an active change.