Considered together the ISA-88, 95 and 106 standards can be intimidating and confusing due to their large, overlapping scope, their different level of specialization and viewpoint. However their shared history, expert community, and domain of interest makes them conceptually consistent. This article proposes three simple but still expressive models to address the intended use cases of these standards. They can be specialized in any of the models in these standards providing a robust basis for an object oriented implementation. They can be used independently of these standards to develop industry / enterprise specific interoperability and functional design languages.