MUSICAL_KEY

Musical key in which the sound starts.

It is represented as a string with a maximum length of three characters. The ground keys are represented with "A","B","C","D","E", "F" and "G" and halfkeys represented with "b" and "#". Minor is represented as "m" (e.g. "Dbm"). Off key is represented with an "o" only. This notation might be extended in the future to support non-minor/major keys.