I thought the symbols represented Coalition (U.S.) roadblocks. Thats how much I know - don't know if unit type/size is represented.
No, I mean that you can see that some unit designations have a little "X" above the image, and some don't. This would indicate their size.
I think that either 2 or 3 x's above the image means a division, but I guess someone will clarify this for us on this thread in time. The other designation must mean airborne (you can see the little "V" wings.