2-39 In the MechaniGram, if A4 were to shift first and go in motion without coming to a complete stop, a shift by A6 during that motion would constitute a foul. Both must be motionless for at least one second before the ball is snapped. A4 may simply move to the backfield and stop. That would mean there are four backs instead of three and the formation would still be legal. Assuming this were first, second or third down and A3 was wearing an eligible receiver’s number, he would be eligible after A4 moves. If A3 and A4 simultaneously shifted and both stopped for a full second, that would be a legal shift.