Hi, I have a few motorola droid razr phones and I noticed on the back of the battery cover on the lower right hand side each of them has hand written markings. One of them has "L7" written, another has "L 14" written, and another has "L 15" hand written with a black marker. I am just curious as to what the L numbers are used for? I also see another marking (made with the same marker) about an inch and a half to the left of the L number. Two of the three back covers that I have, show marks in this area. The third one is blank in that area. See photos below
So what do the L numbers represent?