The PMC ladder logic sets these variables. #1000 is equal to 1 when coil G54.0 in the ladder is on. #1000 is equal to 0 when coil G54.0 in the ladder is off. #1001, #1002, #1003, #1004 are coils in the ladder. G54.1, G54.2, G54.3, and G54.4 respectively. The machine tool builder is checking logic to be true and sets these bits so the part program can run the correct part of the part program.