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.
Force is the result of energy exerted by a player which provides movement of the ball. The term force is used only in connection with the goal line and in only one direction, i.e., from the field of play into the end zone. Initial force results from a carry, fumble, kick, pass or snap. After a fumble, kick or backward pass has been grounded, a new force may result from a bat an illegal kick or a muff.
After the ready-for-play, each player of A who participated in the previous down and each substitute for A must have been, momentarily, between the 9-yard marks, before the snap.
The captain my choose to free kick or snap anywhere between the hash marks:
a. on the yard line through the spot of the catch when a fair catch is made;
b. through the spot of interference, when a fair catch is awarded; or
c. at the succeeding spot when the distance penalty for kick-catch interference is accepted following an awarded fair catch and the down is not replayed.
These choices remain if a dead-ball foul occurs prior to the next down, or a foul or an inadvertent whistle occurs during the next down and the down is replayed.
A game official shall indicate the ball remains dead by sounding his whistle immediately when a foul occurs before a snap or free kick.
The Zebra Files 