 In the last major revision of the catalogue (1964, K6), the Anhang was extended to include doubtful and spurious works.On the basis of the most recent research and discoveries, some of the old K1 Anhangs were promoted to "K" status, while others were relegated from the main catalogue into the K6 Anhang.However, as Zaslaw points out, the Köchel catalogue allocations between main listing and Anhang are not reliable indicators of authenticity or otherwise.