I did a quick search and found out that this is called "target location" in law enforcement jargon. The "one" side is the side of the house or building where the main entrance is located. Then as you move clockwise around the building, side two is the side around the corner to the left, side three is the back, and side four is the side to the right when you look from the front or to the left when you look from the back.
So the one-four corner is the corner to the right of the main entrance when you face the building from the front.. I'm not sure how this system would work with a building that's not rectangular.