And so is JACK if i'm not mistaken ;-).
Not as an acronym, or at least, not one I am aware of. Besides 'jack' is a
generic concept. It's something you plug in to. XLR does not have the
benefit of having a vague meaning :)
Besides It doesn't speak well. "Ziller". XAP (in US anyway) would be
"zap". That is kind of cool. An XAP instrument could be 'zappy'.
Tim