The first thing you should understand is ALIGNMENT.  The graphic above illustrates how we name and number our gaps and alignments. 

The odd numbers designate an “outside shade” of the offensive linemen and tight ends (U).  The even numbers designate a head up alignment on the offensive linemen and the tight ends.  The even numbers with the letter “i” designate an inside “shade” or alignment on the offensive lineman and tight ends.

The GAPS are lettered A through D.  Each gap illustrates the space between each of the linemen and tight ends.  D is special because it is outside of the TE, and this can be a wide or outside angle of the play or even completely wide and almost parallel to the line of scrimmage (LOS).

Inside Linebackers have an alignment and technique designated by a tens (10’s) number.  The first number is the alignment based on the numbering and numbering with “I” designation previously explained and the second number being a zero “0” means you line up off the ball.  Inside linebackers should be 4-5 yards off the LOS.