Jazz chords are always interesting and a good way of learning new ways of doing things. I think it wasn;t that long ago that I saw my first '5' chord. A5 - and I scratched my head for a while. 5? then I realise it signified the lack of the 3rd in the triad - not Major, not minor - essential a power chord. A-D-A in this case. Never seen it notated before. Since then I've seen it a few times, but I guess my music style wouldn't have this chord in it very often, so while perfectly proper, I'd not seen it before. Music theory is never dull. Always appears to be, of course.