Yes, thank you: that's what I'm seeing as the more common usage today than the one I used to understand -- that any branch in canon, no matter how wide the divergence, isn't a "real" AU. Even Trek's Mirror Universe is apparently not considered an AU, because it technically diverged from the prime reality at a historical point.

If divergence and "What if?" scenarios are not a sub-type of AU, is there another category name for them -- a term that identifies them as distinct from strictly canon-compliant stories?