The braket means that there was an interference that the beam picked up in the foreground or background. This csn also be caused by ranging without a steady hold when you ranged the object. In any case it's an indication that you should either take another reading making sure you are steady, or switch to the near or far mode if you visually determine that there is sn interference that can be causing the error. Once you become familiar with the controls of the G7 and the various ranging situations, determining accurate ranges will become instinctive, and very fast.