To help with where you stand or “alignment” on the field, and what your responsibilities on the play are, or “assignment”. The spaces around the offensive line are numbered, and gaps given letters.
Often your alignment will be referred to by number: example “strong 3” would be the outside shoulder of the Guard on the left.
LB techniques are exactly the same but we add a Zero to show the difference between DL/DT and LB techs
If it were “strong 30” you would be the same position but five-six yards away from the Line of Scrimmage (LOS). Your assignment might be the “B-Gap” which is where you run to on a run play. Pass plays have different assignments.
