I will continue with the exegesis of ISO 15926-2 : the
Upper Ontology for Individuals
These classes are members of the metaclasses of Lesson2. In the diagram that is shown with 'type', which stands for rdf:type ("rdf:type is an instance of rdf:Property that is used to state that a resource is an instance of a class.").
The above picture shows the rdf:type (memberOf) relation between the entity types in this Upper Ontology for Individuals and the entity types in the Upper Ontology for (meta)Classes, e.g. Person is a member of ClassOfPerson (see graph below).
That can be illustrated with the following graph that you also can find in the topic "Extended Data Model" (it makes sense to read that):
A quick count tells us that these aren't the earlier-mentioned 201 entity types, for once none of the (ClassOf)Relationships are shown. You can find those here (find the diagram and click on the red dots).
But again, don't get too intimidated, you aren't intimidated by an ordinary dictionary either (that has far more terms) because you know the grammar to use them. Part 2 is your new grammar.
This Upper Ontology for Individuals serves as the 'grammar' for instances of PossibleIndividual and its subclasses.
An example
Combined with the ClassOfDirectConnection from the previous lesson we get 'cascading ontologies':
4D Model
The model of Part 2 is a so-called 4D data model, where 4D = space + time. For that the concept of "temporal parts" is used. It is essential that that concept is understood, so you are advised to read this topic. Understanding this concept may require a paradigm shift, which often is not so easy. In a later lesson we will address the concept of Templates, and most templates have temporal parts in their definition.
Chapter 2 of this publication is a good read in case you want more background information.
What's next?
Because ISO 15926 is about data management and OWL isn't meant for that, we decided to use RDF. In RDF we defined each and every entity type and the 'domain' and 'range' of each predicate.
Taking the above example we define the DirectConnection Relationship as follows:
dm:DirectConnection rdf:type owl:Class ; rdfs:subClassOf :ConnectionOfIndividual ; owl:disjointWith :IndirectConnection . dm:hasSide1 rdf:type owl:ObjectProperty ; rdfs:domain :ConnectionOfIndividual ; rdfs:range: :PossibleIndividual . dm:hasSide2 rdf:type owl:ObjectProperty ; rdfs:domain :ConnectionOfIndividual ; rdfs:range: :PossibleIndividual .
RDF is not suitable for validation (neither is OWL). But luckily there is a RDF-based W3C Recommendation called 'SHACL', that does the job for us. This will be discussed in detail in one of the last lessons.
For now this is the end of the 'grammar' part of the ISO 15926 standard.