That is a command that could be used to figure out how close something is to a target, but it is used to find out if a target is blocking its path. There is a way to find out if an object is say north-east of the tank. I've tried it, but was only able to find anything on the north-west or south-west sides. So, if the object is north east of the tank, and the person is north-east of the tank, and the distance is greater between the person and the tank than the tank and the object, then the tank is being blocked by something.
(Sounds like ranting)
Thanks,
Bluelikeu