I think what our Komrade is asking about is the compass rose that appears when using a tool. It's used by dragging a line out, from your boat to a target, as you read the bearing off the BACK of the rose as you drag it out....this gives you an actual magnetic bearing from you to him.
If you then go to say the scope or UZO, you would turn to that bearing to see the target.
If that don't help, try Wazoo's great guide....here:
http://www.paulwasserman.net/SHIII/