Hi Calum, I was thinking along these same lines. I like the idea of keeping the ABC 'level 1' standard somewhat small, but allowing (OK, I'll say it) scripting languages to manipuate them to produce more complex output.
I think to produce the kind of output our Lilypond friends are used to, you really need to go beyond nouns and into the world of verbs. To subscribe/unsubscribe, point your browser to: http://www.tullochgorm.com/lists.html