What causes "reverse" moves?

[LovinMitts]

This really doesn't really concern me gameplay-wise, but I've just been curious. What causes certain moves to become reverse, such a Sheik's reverse fair, or the reverse knee? What causes the move to send you in the opposite horizontal direction? My only guesses are that it's a property of certain hitboxes when they connect at certain angles, or that it could just be an engine quirk.

 

[EPsilon933]

When they hit with the back side of the hit box

 

[LovinMitts]

When they hit with the back side of the hit box

How underwhelming and non-technical lol. Dang. That makes too much sense.

 

[Magus420]

Doesn't matter what part of the hitbox it hits with. It's just based on which side of TopN you are compared to their TopN horizontally. When you're hit you and the KB are turned to face towards their TopN. TopN is the bone at the base of the character indicated with a white + in develop mode.