The Köchel-Verzeichnis or Köchelverzeichnis is a chronological catalogue of compositions by Wolfgang Amadeus Mozart, originally created by Ludwig von Köchel, in which the entries are abbreviated K.and KV. The numbers of the Köchel catalogue reflect the continuing establishment of a complete chronology of Mozart’s works, and provide a shorthand reference to the compositions.
According to Köchel’s counting, Requiem in D minor is the 626th piece Mozart composed, thus is designated either K. 626 or KV 626; however, his original catalogue (1862) of Mozart has been twice revised, and some works have had three KV. numbers, e.g. Mozart’s Horn Concerto No. 1, K. (412+514)/386b.
Source: Köchel catalogue – Wikipedia








