 In some instances the main body of the work has been entirely lost, its identity being preserved only through an incipit (record of the opening few bars) cataloged by Breitkopf & Härtel, who published the "Alte Mozart-Ausgabe" (AMA) in 1883.The informal 18th century methods of publishing and distributing musical works caused additional confusion.Cataloging errors based on inadequate information, and an occasional over-eagerness to attribute new discoveries to Mozart has added to the problem.