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Thank you. We'll be sure to be more aware of that in coming episodes. Thanks for watching.

I have a bit of the opposite feeling, I often see UNS evangelists refer to ISA95 Part 2 as the only useful part, and then go ahead and reduce it to the role based equipment hierarchy model that's actually in Part 1, and even use the discrete mfg version instead of the general one at that. The hierarchy model is defined in Part 1, the information/object model in Part 2 (and 4), and it's all valuable.

Part 1 of the ISA-95 standard provides the foundational models and terminology used throughout the rest of the standard. It touches on the broad definition of role based equipment hierarchy 'levels' and provides the familiar Enterprise-Site-Area-WorkCentre-WorkUnit model. Part 2 of the standard expands on this basic hierarchy and provides models and attributes that represent the equipment in a much more detailed and comprehensive way - attributes, properties, relationships to other equipment, etc.

UNS evangelists focus on the equipment hierarchy because they are mostly concerned with the current state of the equipment. It's worth remembering that the ISA 95 standard defines dozens of models, one of which is the Equipment model.

Walker refers to ISA-95 Part 2 when discussing the UNS. He has commented that Parts 1, 3 and 4 are not necessary and people do not use them. There are really three items in play. The first is thee "Role based equipment hierarchy model" from Part 1 which defines the equipment levels. The second is the "Role based equipment model" from Part 2. The third are equipment model attributes (Part 2) which are "Hierarchy scope" and "Equipment level." The equipment level attribute is based on the enumerated set from the Part 1 model. It should be noted that the list is not exhaustive which means other equipment levels can be defined (Laboratory, Mobile Equipment Pool, Unused Equipment Store, Transportation Center). Equipment level and hierarchy scope are not needed if they can be inferred from the information. In this case, if there is an MQTT topic structure, they may not be needed. It is a rather nuanced topic.