Open source is important for music as well: musicxml, ly, musescore, or at least midi. The composition can be public domain all day long, but pdfs are a chore to turn into music and audio files are hopeless. More regrettable yet when the only thing keeping the audio files from being public domain is copyrighted samples. I'm looking at a certain illustrious website of music generously released to the public domain by living composers who don't understand why people would want the source midi.