This topic is to show how our proverbial pump P-101 fits in ISO 15926.
The blue part shows a subset (~10%) of the ISO 15926-2 data model, starting with ClassOfIndividual and PossibleIndividual. These are specialized as shown.
The RDL - Reference Data Library - contains instances of the subclasses of ClassOfIndividual (and many other things that are not relevant in this context). These are also subclasses of subclasses of PossibleIndividual (see ARTEFACT in above diagram).
Most instances of (subtypes of) ClassOfInanimatePhysicalObject start, in the top of their hierarchy, with being a specialization of an instance of ClassOfFunctionalObject. In above diagram CENTRIFUGAL PUMP is a subclass of the instance PUMP of ClassOfFunctionalObject.
CENTRIFUGAL PUMP, or any of its many subclasses (not shown) is the superclass of a so-called Requirements Class, often defined in a Specification (here, in this example for pump P-101, such as an API 610 Pump Data Sheet).
Pump P-101 is declared as an instance of InanimatePhysicalObject, as a member of RDL class PUMP, as an instance of NonActualIndividual, and as an instance of WholeLifeIndividual.