A bound manuscript written on vellum and pertaining to orthography, or the art of spelling as a science. Written by De Altedo, the work is dedicated to his friend Baldum (Baldus). The book is dated from internal evidence in a statement that the scribe "set his pen to work on the first of May of 1297 A.D." No evidence has been located that the treatise was ever published in printed form. The work is bound in heavy boards; five brass bosses are on both the front and back covers.