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
Dr K–Sextett Dr K–Sextett The Dr K–Sextett is a short, occasional composition for six instrumentalists, written in 1969 by Karlheinz Stockhausen and given the number 28 in his catalogue of works. The Sextet was composed as the result of a request made to eleven composers in January 1969 by the London office of Universal Edition for short pieces of music to celebrate the 80th birthday of Dr. Alfred Kalmus, who had been Universal's London director since 1936. All of the pieces were scored for performance by members of the Pierrot Players . Collectively titled "A Garland for Dr. K.", the eleven works