DocBook

Thank you for your suggestion. The DocBook technical committee has
considered your request.

Name spaces were added to DocBook 5, specifically to allow mixing other
XML-based grammars with DocBook. I have looked at the 3.0 release of
MusicXML, and it seems to be quite expressive (although I am not a
musician) and to already have a lot of supporting technology for rendering
the markup into output formats. They have also added XSD schema support to
the 3.0 release.

The committee has decided not to directly address music notation for a
couple of reasons:

1. It is outside the intended scope of DocBook (which is technical
documentation).
2. The name space mechanism allows including other, specialized, XML-based
notation schemas. While the definitive notation schema for DocBook is RNG
with schematron, it is also available in XSD and DTDs (although with
reduced quality of representation of the schema).

Good luck with developing a new schema for music notation. Schema
development is challenging, as is producing the tools to render the schema
into useful representations.

I've actually begun a project on Google code to cover music markup. It's
based on ABC music notation, and if anyone wants to contribute, email me.
It follows the design of ABC notation as closely as possible, so updates
should follow the ABC notation standard at http://abcnotation.com. the
project is here: http://code.google.com/p/sfzml/. The mark up uses RELAX
NG to describe the grammar allowed, but the Schematron schema is going to
cover all the rules of Western music notation, as well as certain markup
constraints as needed.

DocBook focuses on markup for technical documentation, specifically
documents about computer hardware and software.

I wonder if the Publishing subcommittee would be interested in music
markup?