Odo of Arezzo:Several medieval music theorists named Odo have been confused historically. For the other major theorist of this name, see Odo of Cluny. Odo of Arezzo or Abbot Oddo (fl. late 10th century) was a Medieval composer and theorist who worked in Arezzo. Little is known about his life, except that he was an Abbot in Arezzo, working under Bishop Donatus of Arezzo. Odo composed a tonary (a book of chants which usually included antiphons and responsories) with a discussion of modes, which survives in 20 manuscripts, four of which contain attributions to Odo. In several of the manuscripts a prologue ascribed in three out of six to Odo is entitled "Formulas quas vobis".
A has been mistakenly attributed to Odo of Arezzo.