Play situation:
Fumble by A a B-40 recovered by B. During the return B commits IBSB at the A-30, B fumbles at the A-20, ball travels untouched beyond A's end line.
Ruling and enforcement?
Thanks for the help.
Basic spot is the end of the related run (A-20, where the ball was fumbled). If the penalty is accepted, it's enforced from the spot of the foul (A-30) since the spot of the foul is behind the basic spot, per the ABO principle. B's ball, 1/10 at the A-45.
If the penalty is declined, the result of the play is a touchback because the force that put the ball across the goal line is B's fumble. A's ball, 1/10 at the A-20.
A will more than likely decline the penalty.