Usually points to a passenger frontal Stage 4 or staged-restraint branch; the exact circuit varies by manufacturer and VIN.

Usually points to a driver frontal Stage 5 or staged-restraint branch; confirm the VIN-specific definition before naming a part.

The standardized label identifies a monitored passenger frontal Stage 1 deployment-control branch; exact hardware, test procedure, and failure point vary by manufacturer and VIN.

May indicate a monitored passenger frontal Stage 2 deployment-control branch; confirm the VIN-specific circuit before naming an inflator, harness, occupant input, crash-data, or module fault.