This standard PD CLC IEC/TR 62541-1:2021 OPC unified architecture is classified in these ICS categories:
25.040.40 Industrial process measurement and control
35.100.01 Open systems interconnection in general
This part of IEC 62541 presents the concepts and overview of the OPC Unified Architecture (OPC UA). Reading this document is helpful to understand the remaining parts of this multi-part document set. Each of the other parts of IEC 62451 is briefly explained along with a suggested reading order.