What is "maccam"

MacCAM (often written as MacCam, Mac-Cam or Mac Cam) is a system of slow-motion cameras developed by FastCAM Replay LLC and DEL Imaging Systems LLC used during Tennis matches to replay close or controversial line calls. The system is named after John McEnroe, who was infamous for contesting umpire calls. CBS was the first network to use the MacCam widely, as John McEnroe was one of their tennis analysts.