I'be been using DocBook for some time now, and I've noticed the lack of support for a formal syntax to use for music notation. I have found MusicXML, but that standard is maintained using DTDs; it hasn't even started using RELAX NG or Schematron, calling them "immature" schema languages. I've also been a percussionist for the past 10 years, and if I've noticed anything on music notation, DTDs are a downright joke to try and make a decent music notation markup language; music is simply too complex in nature. I'd like others opinions to help add a useful, well-defined music notation markup language to DocBook. Thanks to anyone who can help.