Köchel catalogue son's earlier works; Mozart's catalogue of his own compositions (begun in February 1784 with K. 449) allows relatively precise dating of many of his later works. The catalogue included the opening bars of each piece, known as an incipit. Köchel divided the corpus into a main chronology of 626 works, and five appendices ("" in German, abbreviated to "Anh.") The appendices (Anh. I-V) included: Since Köchel published his original catalogue in 1863 (now referred to as K), the dating of Mozart's compositions has been subject to constant revision. Many more pieces have since been found, re-dated, re-attributed and re-numbered, requiring
Large numbers If we need many such functions we can better number them instead of using a new letter every time, e.g. as a subscript, so we get numbers of the form formula_81 where "k" and "m" are given exactly and n is an integer which may or may not be given exactly. Using "k"=1 for the "f" above, "k"=2 for "g", etc., we have (10→10→"n"→"k") = formula_82. If "n" is large we can use any of the above for expressing it. Thus we get a nesting of forms formula_83 where going inward the "k" decreases, and with as inner argument a