No player, other than the snapper, shall encroach on the neutral zone after the ball is ready for play by touching the ball or an opponent or by being in the neutral zone to give defensive signals.
Tag: encroach
Rule 7, Section 1, Article 7
After the ball is ready for play and before the snap begins, no false start shall be made by any A player. It is a false start if:
a. A shift or feigned charge simulates action at the snap.
b. Any act is clearly intended to cause B to encroach.
c. Any A player on his line between the snapper and the player on the end of his line, after having placed a hand(s) on or near the ground, moves his hand(s) or makes any quick movement.
The Zebra Files 