Many Classical composers have what are know as "Opus" numbers. An example from my music is "Bach - Hanssler - Harpsichord Concerto In A Major, BWV 1055" where 1055 is the Opus number. (Mozart's are called K for some reason.)
I enter this as the "Track" number because the track usually is unimportant for a classical CD, as you will most likely be joining tracks anyway. This then allows me to sort my classical composers by Opus number, and also see which ones I am missing.
Mozart's works are labelled with a "K" because of the guy who came up with an organizing system for them--Ludwig von Köchel, who compiled a more or less complete chronological inventory of Mozart's works seventy years after the composer's death. In German it's called the Köchel-Verzeichnis, or "Köchel Listing", abbreviated KV; we just replace the usual "opus" or "op." with "K". (And BWV stands for Bach-Werke-Verzeichnis, or "Listing of Bach's Works".)
Mozart's works are labelled with a "K" because of the guy who came up with an organizing system for them--Ludwig von Köchel, who compiled a more or less complete chronological inventory of Mozart's works seventy years after the composer's death. In German it's called the Köchel-Verzeichnis, or "Köchel Listing", abbreviated KV; we just replace the usual "opus" or "op." with "K". (And BWV stands for Bach-Werke-Verzeichnis, or "Listing of Bach's Works".)
I mean, just so you know.