Foul or incidental contact?

[CoachP]

Originally Posted by rfp

So in this situation, you can have a trainwreck -- and everyone in the gym howling -- and no foul.

From what I've read around here (and heard from peers in the area):

If B1 hits A2 and stops as soon as he/she makes contact, no foul. I suppose A2 still could go flying--flopping....

If B1 hits the screen and proceeds "thru" A2, then it's a foul. This case is more than likely the "train wreck"