Opus number developed other catalogue-number systems; among them the "Bach-Werke-Verzeichnis" (BWV-number), and the "Köchel-Verzeichnis" (K- and KV -numbers) with which are organised the works of Johann Sebastian Bach and Wolfgang Amadeus Mozart, respectively. In the classical period, the Latin word "opus" ("work", "labour") was used to identify, list, and catalogue a work of art. By the 15th and 16th centuries, the word "opus" was used by Italian composers to denote a specific musical composition, and by German composers for collections of music. In compositional practise, numbering musical works in chronological order dates from 17th century Italy, especially Venice. In common usage, the
The Smith of Kochel known as "Balthasar" with a last name of either "Mayer" or "Riesenberger". A "Balthasar Mayer" (born January 6, 1644 in Waalkirchen) actually existed, but no evidence of this person being a smith in Kochel could be found. A "Balthasar Riesenberger" (born in Bach bei Holzolling) took part in the battle in Sendling, but no evidence of his being a smith in Kochel could be found either. The fact that Kochel belonged to the court district of Murnau at the time of the revolt, which did not take part in the Oberländer rebellion, also speaks against the Kochel theory. In memory