A manufacturer provided means performing specific actions if the integrity of the PES is violated.

A manufacturer provided means which independently monitors the Duration of internal hardware functions, and/or Application Program functions, and/or Operating System Software functions, and which will cause specific actions to be performed if not periodically reset at a predetermined interval.

In control systems, a combination of hardware and software which acts as an interlock scheme, disconnecting the system's output from the process in event of system malfunction.