The AT-number system was updated and expanded in 2004 with the publication of "The Types of International Folktales: A Classification and Bibliography" by Hans-Jörg Uther. Uther noted that many of the earlier descriptions were cursory and often imprecise, that many "irregular types" are in fact old and widespread, and that "emphasis on oral tradition" often obscured "older, written versions of the tale types". To remedy these shortcomings Uther developed the Aarne–Thompson–Uther classification (ATU) system and included more tales from eastern and southern Europe as well as "smaller narrative forms" in this expanded listing. He also put the emphasis of the collection more explicitly on international folktales, removing examples whose attestation was limited to one ethnic group.