After koseki (Japanese family registry) and other official documents under the ritsuryo system (the historical law system based on the philosophies of Confucianism and Chinese Legalism in Japan) ended up at Todai-ji Temple as scrap paper, the back side of that paper was used for creating records.
戸籍などの律令制の公文書が反故として東大寺に渡り、その紙背を東大寺は記録紙などに利用した。