I have no idea if something like this is even possible :)
Lets say you have a vocal track that is 2 minutes long.
You could put the cursor where the chorus is, lets say at 1:10
and type in "chorus" and the type in bridge at say 1:00
and "bridge" will be tagged on the file at 1:00?
You could type in lyrics right on the audio file
and also type in chords/scales/modes being used
at any point/time on any track and so on and so on.
forgive the art..
I hope I am explaining this clearly enough.(just woke up)
This would serve the same sort of purpose as
adding chord grid images to each track when you want the chords
listed by the tracks but without having to add a track
for each one.
http://forum.cockos.com/showthread.php?t=40050