The SafetyConsumer uses the MNR to detect mis-timed SPDUs, e.g. such SPDUs which are continuously repeated by an erroneous network storing element. A different MNR is used in every RequestSPDU of a given SafetyConsumer, and a ResponseSPDU will only be accepted, if its MNR is identical to its matching RequestSPDU.

The checking for correctness of the MNR is performed by the SafetyConsumer, only.