This part of IEC 61158 provides common elements for basic time-critical messaging communications between devices in an automation environment. The term "time-critical" is used to represent the presence of a time-window, within which one or more specified actions are required to be completed with some defined level of certainty. Failure to complete specified actions within the time window risks failure of the applications requesting the actions, with attendant risk to equipment, plant and possibly human life.Cross References:ISO/IEC 10731IEEE Std 802.1QISO/IEC/IEEE 8802-3ISO/IEC 7498-1ISO/IEC 7498-3IEC 61158-1:2019BS EN IEC 61158-1:2019All current amendments available at time of purchase are included with the purchase of this document.