I just did some research for ya, too.
Rule 9.6. Neckrope Must be Used in Tie-Down Roping. In tie-down roping, a neckrope must be used. Calves may
Not be intentionally flipped backward. Contestant must adjust rope and reins in such a manner that will prevent horse from
Dragging calf. Rope to be removed from calf’s body as soon as possible after “tie” is approved. Roping claves shall be
Strong and healthy.
Rule 11.6.5. No Jerk Down. Rodeo Committees have the option to request a special ground rule for “no jerk down” in
The tie down roping.
So the first is subjective (and does not apply to any kind of falling besides a back-flip), and the second is optional.