If you play Starbound you are more than likely yo have come across this, when you hear the Music that you play with instruments in Starbound, Yep that is ABC Notation. it was used in old games when they didn't have software. it is a series of letters which is converted into Notes. so it is effectively a ASCII Music Creator.
You can use what ever Instrument there is in Starbound when you use Starbound Composer
Useful Links on ABC Notations