[RQ7.2] SafetyData shall contain the safety-related application data transmitted from the SafetyProvider to the SafetyConsumer. It is comprised of a single or multiple basic OPC UA Variables (see 6.2.5). For the sake of reducing distinctions of cases, SafetyData shall always be a Structure, even if it comprised of only a single basic OPC UA Variable.

For the calculation of the CRC signature, the order in which this data is processed by the calculation is important. SafetyProvider and SafetyConsumer shall agree upon the number, type and order of application data transmitted in SafetyData. The sequence of SafetyData is fixed.

SafetyData may contain qualifiers for a fine-grained activation of fail-safe substitute values. For valid process values, the respective qualifiers are set to 1 (good), whereas the value 0 (bad) is used for invalid values. Invalid process values are replaced by fail-safe substitute values in the SafetyConsumer’s safety application. See 6.3.6.