'Kakuhitsu' is a chopstick-shaped writing tool of ivory or bamboo, with which priests of the Heian period made interlinear glosses of characters and sympols when reading Chinese scriptures translated in Japanese. Their marks left on paper are concave as if scratched with a nail, unlike the case of ink of various kinds. A document with 'kakuhitsu' writing was first found out ten years ago, and since then there have been discovered forty-seven pieces.
Shamijikkaiigikyō (沙弥十戒威儀経) owned by Ishiyama temple, the most important of those documents, abundantly retains the characters and symbols written with a 'kakuhitsu' in the mid-Heian period (the tenth century). The present study, which attempts to throw light upon the special qualities of 'kakuhitsu' writing, deals with the phonological, grammatical and lexical features, as well as the shapes and functions, of the characters and symbols used in this special methods of writing.