Although 'iroha order' contains 47 characters as recited in 'The Iroha' (a Japanese poem, probably written sometime during the Heian era), the iroha order in 'Isebon' and 'Indobon' consisted of 44 characters excluding 'ゐ' (wi), 'ゑ' (we) and 'お' (o).
「伊勢本」・「印度本」では「いろは順」は「いろは歌」のような47文字ではなく、「ゐ」「ゑ」「お」部が無い44文字で構成されていた。