The GUIDO Music Notation
Format is a system designed to logically represent all aspects of music in a computer
-readable format. It is designed to be a superset of the standard Common Music Notation, and includes facilities for automatically converting from the GUIDO format to standard sheet music
See also GNU LilyPond. The primary difference between the two systems (which superficially are very similar) is that GUIDO is designed to represent music in a logical format (with the ability to render to sheet music), whereas Lilypond is more narrowly focused on typesetting sheet music.