User blog comment:KidVegeta/Canonicity/@comment-3097771-20101009013004

Fusion reborn is non-canon. This doesn't mean it's in an alternate universe, but rather, it has no place anywhere. It's just a fun movie to watch, with no placement in the true canon.

History of Trunks is indeed canon, but since it's in an alternate timeline, I felt it was better to classify it as irrelevent.