Modest as I am, I'd suggest starting with all music and working out from there. One rule to bind 'em, or something. A real standard that, once learned (which would be much easier for all...) would be useful for all musicians, worldwide and for ever. That'll do for starting out, I reckon.
Generous as I am, I'll not even be patenting nor copyrighting the genial idea. I humble statue in a prominent location of most capital cities will be enough reward, probably.