Hi,
I'm coming late to this discussion, but potentially *very* excited about what this might mean. Will the available of spanner IDs mean that a single voice will (eventually) be able to carry multiple *text spanners*???
This would be incredibly useful in my own scores (and probably also in the scores of very many other composers who work with simultaneous continuous transitions). I've attached a PNG of an example from a recent cello piece. The score is in LilyPond, but the engraving required multiple (redundant) invisible markup voices. Would be so elegant to be need only a single voice.
Trevor.