Part 2 extended data model

latest update: 17 June 2017    


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/OWL does 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, typically, both shall be declared.
  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 required an update, these will be incorporated in Part 2.

The EDM is set-up such that it is possible to use:

  • the Part 2 data model without extensions, or
  • the federation of the Part 2 data model and the EDM, since the ClassOfArrangedIndividual is deprecated in the EDM, its subtypes are, in the EDM, being redeclared as subtypes of the new ClassOfPhysicalObject that replaces that ClassOfArrangedIndividual.

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

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 Extended Data Model.