digital chalking
n.— «During a recent trial run, a city employee drove the Ford Explorer. Scanning parked cars and trucks, a method known as “digital chalking,” the cameras routed information to a computer. The next time the city vehicle passed the parked vehicle, the camera system would determine if it had been in the space longer than permitted.» —“Canton says no to parking cameras” by Ed Balint The Repository (Canton, Ohio) Sept. 12, 2006. (source: Double-Tongued Dictionary)