Each grid location is referenced by "letter-number", with letters starting at
A and going from left to right, with numbers starting with 1 going from top
to bottom. Therefore, the top left corner is A1.
The actual area of each square varies by map.
Additionally, the grid coordinates for the square you are currently in is
displayed in your Proximity Map, and the locations of
squad and platoon members is displayed under their
name on the HUD.