Köchel catalogue 225: The New Complete Edition" contains premiere performances of previously lost compositions and never recorded fragments, as well as key works in alternative versions and recordings of legendary historic performances. Köchel catalogue The Köchel catalogue () 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,
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