For 2021:
4/10, B-40, 0:12 (4), A=14, B=14.
A11 advances to the B-31, where he is contacted by opponents, but is moving forward when he attempts a backward pass to A89 from the B-30. A89 first touches the ball at the B-29, completes the catch, and advances to the B-10, where he is forced out of bounds after time has expired in the period.
Ruling: B may decline the penalty for the illegal forward pass (made from beyond the NZ) and allow the game to move to an Extra Period, or B may accept the 5-yard penalty at the spot of the pass (B-30), with a loss of down, which will award the ball to Team B at the B-35. Team B will then be given the option to extend the period for an untimed down, OR allow regulation play to end, and move to an Extra Period. If Team B opts to extend the period, the next down will be B, 1/10, B-35, no game clock (25). (Here is where the R uses the "finger twirl" signal to notify the GCO and the pressbox that the next down will be an untimed down. The GCO doesn't care, because he has already figured this out, has grabbed the last chicken wing off the buffet, and is on the elevator down to the ground level, headin' for his car.)
They could go for the hail Mary, or have a rugby-style scrimmage with multiple running plays with backward passes. Or, they could disappoint everybody and take a knee.
The 2021 rule change would appear to make this a viable option. Previously, the period would have ended - no option, due to the loss-of-down in the penalty statement. But the 2021 rule change gives the offended team the option to extend the period for a foul that has loss-of-down in the penalty statement.
Have I got this right?