Part 2 extended data model

latest update: 2018-09-18    


The Extended Data Model is the place where we introduce entity types that were "forgotten" in Part 2, such as Person, Organization, InformationObject, etc. We need such entity types: 

  • to enable us to further specialize templates at meta model level. For example the template SkillOfAPerson;
  • to enable to declare these individuals.

This topic also gives information about the way the entity types from the ISO 15926-2 Upper Ontology relate to instances thereof in the ISO 15926-4 Reference Data Library, and how to the added subtypes of Part 2 PossibleIndividual.

Also visit the topic that applies this for a pump P-101.


  1. The difference between "instance" and "member" is that an instance is for membership of a Part 2 entity type, and member is not. RDF and OWL do not know that distinction.
  2. The EXPRESS SUBTYPE OF relationship between two entity types translates to rdfs:subClassOf in Part 8.
  3. An individual pump is an Ur-Element : "an object (concrete or abstract) which is not a set, but that may be an element of a set". (instances of relationship and multidimensional_object are also Ur-Elements).
  4. The rdf:types are often redundant, but useful from an application point of view. Part 8 dictates that rdf:type shall be declared for each Thing..
  5. The added entity types are, provisionally, stored in the Part 12 lci: ontology (lci = life cycle integration). In the future, at the time that Part 2 requires an update, these will be incorporated in Part 2.

The extended data model is set-up such that it is possible to use:

  • the Part 2 data model without extensions ("pure Part 2), or
  • the federation of the Part 2 data model and that extension; since the ClassOfArrangedIndividual is deprecated then, its subtypes are as well in the extension, being redeclared as subtypes of the new ClassOfPhysicalObject that replaces that ClassOfArrangedIndividual (see here).

These new entity types fit in the Part 2 model as shown in the graph below *).

Extensions to ISO 15926-2 data model *)

  *) The additions of members of the other subtypes of ClassOfPhysicalObject are not shown for editiorial reasons. They cannot be instantiated and are used as top of a hierarchy in the RDL only.

Specialized entity types for use in ISO 15926-7 Templates

A number of classes are "fixed" in some templates,.  In a limited nunber of cases other classes need to be added to the edm: ontology.

Two examples:

  1. In the template DefinitionOfShape2AxisPlacement we find the complex class tpl:ClassOfInformationObjectANDAxis2Placement
  2. In the template ReferenceScaleDefinition we find tpl:UomSymbolAssignment as defined in ISO 15926-7 sub 7.2. This is a specialization, not an instance, of dm:ClassOfClassOfIdentification. The reason why it is a specialization and not an instance is that the classes in the dm ontology, geo ontology, tpl ontology and the tm ontology are upper ontology classes of which the objects in the Reference Data Library and in the data stores are instances. Classes like this tpl:UomSymbolAssignment are in fact singleton classes with at maximum one instance in the RDL.


Click here for the listing of the data model extension.