What is the secret of opus numbers in classical music?

Have you ever seen the word "Op."?

For example, "Op." is used in the names of classical music works, such as Chopin's "Waltz in C sharp minor Op.64-2" and Beethoven's "Sonata Op.49-2 First Movement."

In fact, this is pronounced "opus" and is a work number assigned to each composer's work to categorize it. In Japan, it is sometimes called "work number ○○".

There are several ways to write this work number, and the most typical one is "Op".

However, there are also opus numbers named after musicologists who specialized in categorizing the works of a particular composer.

This time, I would like to introduce a few of them.

kechel number

The Köchel number is the opus number used for Mozart's works, and is derived from the name of musicologist Ludwig von Köchel. They are arranged in chronological order from K.1 to K.626, and K.626, Mozart's last work, is the famous unfinished work ``Requiem.''

deutsch number

The Deutsch number is the opus number used for Schubert's works, and is derived from the name of the musicologist Otto Erich Deutsch. They are arranged in chronological order from D1 to D998, but Deutsch himself is particular about how they are written. It is generally written as D1 instead of D.1 because we want D to be used as the number for Schubert's work (because adding a period would be an abbreviation of Deutsch's name).

hoboken numbers

The Hoboken number is the opus number used for Haydn's works, and is named after musicologist Anthony van Hoboken. The works are arranged by genre from Hob.Ⅰ to ⅩⅩⅩⅠ, and the works are numbered even more precisely.