American Football Rules IFAF Approved Ruling 7-1-3:V

V. A66, a restricted lineman between the snapper and the player on the end of the line, or A72, a restricted player on the end of the line of scrimmage:

1. Lifts a hand or hands from the ground immediately when threatened by B1, who is in the neutral zone. RULING: Blow the whistle immediately. Team B dead-ball foul,
   offside. Penalty — Five yards from the succeeding spot.
2. Lifts a hand or hands from the ground upon initial charge by B1, who (a) does not enter the neutral zone or (b) enters the neutral zone but does not threaten the position of A66 or A72. RULING: In both (a) and (b), blow the whistle immediately. Team A
   dead-ball foul, false start. Penalty — Five yards from the succeeding spot. [Cited by 2-18-2-d, 7-1-2-b-3-a, 7-1-5-a-2]
   NOTE: Before the snap, a team B player who enters the neutral zone may threaten a maximum of three Team A linemen. If the Team B player enters the neutral zone directly toward a Team A lineman, then that Team A player and the two adjacent linemen are considered to be threatened. If the Team B player enters the neutral zone directly toward a gap between two Team A lineman, then only those two Team A players are considered to be threatened.