Most of the monjo which were created by authorities and reports collected from various provinces under ritsuryo system (the historical law system based on the philosophies of Confucianism and Chinese Legalism in Japan) were disposed of after a short period (except koseki [Japanese family registry] - these were kept a little longer, for about 30 years), but the Sutra copying office at Todai-ji Temple used the back sides of the waste monjo as ledger paper.
律令制下で官庁が作成した文書や諸国からの報告書のほとんどは短期間（戸籍の保存期間は比較的長く30年）で廃棄されていたが、東大寺写経所では廃棄文書の裏面を帳簿として再利用していた。