Understanding the Football Tackle Box: Vertical and Horizontal Movement

Question
how is the "tackle box" defined vertically/horizontally in high school football? does this "box" move as the play progresses or is it solely defined at the line of scrimmage pre-snap

thx

Answer
    The tackle box does not move after the snap in a horizontal fashion.  It does however move vertically after the snap.  Generally it is a judgement call by the line judge or umpire on any cliping or cut blocks, inside the box.  On pass plays the box does extend backwards into the offenses backfield.  On run plays the box does not extend foward more than about 2 yards.  Hope that helps some.  COACH NOEL!