7-2-5 Exception 1 Illegal numbering. On first, second or third down, if the formation has no player with a knee on the ground in position to receive the long snap and another in position to be a kicker, it is a scrimmage kick formation but the numbering exception may not be used.
7-2-5 Exception 1 On first, second or third down, when the kicking team sets or shifts into the scrimmage kick formation with a holder, only one lineman may wear a number other than 50-79 inclusive. That player must snap the ball and must be positioned between the ends. He remains an ineligible receiver throughout the down unless the opponents touch the ball.