In the decades after Mozart’s death there were several attempts to catalogue his compositions, but it was not until 1862 that Ludwig von Köchel succeeded in this enterprise. Many of his famous works are referred to by their Köchel catalogue number; for example, the Piano Concerto in A major (Piano Concerto No. 23) is often referred to simply as “K.488″ or “KV.488″. The catalogue has undergone six revisions.