The line of scrimmage is an imaginary line, extending from Sideline to Sideline, parallel to the Goal Line, and passing through the point of the ball farthest from Team A's Goal Line.
Players of Team A whose facemask is in line with or in advance of the Centre’s backside, and is on their own side of the line of scrimmage, and are formed in a single line when the ball is put in play, shall be considered scrimmage line, or ”Line Players”.
A player of Team A is considered to be in the backfield if such player is clearly not a Line Player when the ball is put in play. The player occupying the position of Quarterback shall be considered to be in the backfield and not be a Line Player.
No player of Team A shall be in a position that will create doubt as to being on the line or in the backfield, when the ball is put in play.
The scrimmage zone is the area extending one yard on each side of the line of scrimmage and from Sideline to Sideline.
On a play from scrimmage, players of Team B must line up at least one yard back of, and on their own side of the line of scrimmage until the ball is put in play. This includes the player giving defensive signals.