ISO 15926 Architecture

latest update: 2015-12-13    


The OWL/RDF implementation of ISO 15926 consists of many interrelated and distributed modules, as is shown above. Each module has its own rate of change and related versioning. The data model, for example, has not changed since the year 2003, and project data at the other end of the spectrum change daily.

There are four main partitions:

  1. The ISO 15926 upper ontologies (meta models) expressed in OWL format;
  2. The RDL and extensions of the RDL, as defined by organizations, in RDF format;
  3. The "work horses" of lifecycle information and local reference data, expressed in RDF;
  4. A selection of the lifecycle information, mapped to OWL, for reasoning purposes.

and two auxilliary partitions:

  1. Template Specifications, expressed in XML;
  2. Part 7 Proto Templates, in FOL (First-Order Logic).

The various modules are being discussed below. These are accessible by clicking the applicable symbol in the above diagram.

Please refer to the paper Redefinition of the Template Model for the underlying principles.

ISO 15926 OWL models

dm - Part 2 Data Model

ISO 15926 starts with a data model, as defined in ISO 15926-2. In this ISO standard this data model is written in EXPRESS, the modelling language of the ISO 10303 ("STEP") suite of standards. See here.

For the purpose of ISO 15926 (Industrial automation systems and integration — Integration of lifecycle data for process plants including oil and gas production facilities) in Part 8 of that standard the choice has been made to use the technologies of the W3C Semantic Web.

This made it necessary to map the data model from EXPRESS into OWL . The mapping has been done by PoscCaesar. Their website gives a lot of information about the process and the results.

The OWL version of the data model can be found at (Mozilla Firefox may give problems presenting that, IE does not).

geo - Part 3 Geometry Model

In ISO 15926-3 a data model for geometry is defined. That model is an adapted OWL version of ISO 10303-42 that is written in EXPRESS, the modeling language of the ISO 10303 ("STEP") suite of standards.

The geo ontology imports the dm ontology.

The OWL version of the Part 3 geometry data model can be found here. (later)

edm - Extended Data Model

An "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 details see here.

tm - Part 8 Template Model

ISO 15926 Parts 7 and 8 define the concept of Templates.

A ClassOfTemplate is a specialization of dm:ClassOfMultidimensionalObject and of dm:ClassOfClassOfInformationRepresentation.

A Template is a specialization of MultidimensionalObject and of ClassOfInformationRepresentation.

Both have a List structure.

A Template Model generically defines that List structure, with 2 - 11 predicates, and it defines the rdf:object of each predicate in terms of the attributes of dm:ClassOfMultidimensionalObject and MultidimensionalObject. This is fully described here.

Where the template model as such is actually used for reference only, this tm ontology is there for software developers to explicitly give role numbers to the roles of the template signature. The resulting code is made part of the OWL listing of the tpl ontology.

tpl - Part 8 Properties & Base Templates

From the XML code of the Template Specifications the OWL listings are automatically generated and available at  (Mozilla Firefox may give problems presenting that, IE does not).

This tpl Template ontology also maps the template List structures from the tm ontology, and it defines the rdf:object of each predicate in terms of Part 2 and/or Part 3 and/or Part 4 specialized entity types, as defined in the Template Specifications.

Specializations of these "Base Templates" are also stored here, or in a used-defined ontology (not shown on the diagram).

This ontology contains some classes that were "forgotten" in Part 2, such as Person, Organization, etc, where these are necessary for person or organization-specific templates. It also contains some intersections like ClassOfActivity AND ClassOfInanimatePhysicalObject, or dm:ClassOfInformationRepresentation AND geo:Axis2Placement.

The tpl ontology is fully described here.

ts - Template Specifications

According ISO 15926-7, clause 5.1 and ISO 15926-8, clause 6.2 a specification for each template class and each specialization thereof shall be prepared, listing:

  • TEMPLATE NAME - a unique English CamelCase identifier of the lifted and lowered template (translations in other languages are possible and retrievable);
  • DEFAULT RDS ID - an unmutable dm:Thing.ID of the template class;
  • STATUS: the status of the specification (e.g. proposed, for approval, approved, IS);
  • MEMBER OF - a ClassOfClass grouping the template classes;
  • DEFINITION: a narrative definition of the semantics of the template;
  • REPRESENTED INFORMATION - a script text with inserted dereferenced rdfs:label of the role fillers;
  • EXAMPLE: one or more examples;
  • NOTES: hints and instructions for its use;
  • SCOPE NOTE - a note in case of limitations of the scope of the generic template;
  • ADMIN NOTE - a note for action by the administrator;
  • LIFTED AND LOWERED GRAPH: a graph that shows how the lifted template collects the nodes of the lowered template graph, and how the lowered template refers to the variant nodes of the lifted template;
  • LIFTED TEMPLATE ELEMENTS: an alphabetically ordered list of the URIs of all nodes as collected by the lifted template, with the applicable "element" numbers;
  • DEFINITION OF PROPERTIES OF LOWERED TEMPLATE: the Signature List (translations in other languages are possible and retrievable);
  • SPECIFICATION IN FIRST-ORDER LOGIC: a first-order logic-based specification for the formalization of the lifted and the lowered template;

A set of approx. 180 template specifications for base templates has been posted here.

proto - Part 7 Proto Templates

In the FOL listings, defined in the Template Specifications, use is made of Proto Templates as defined in Part 7 Annex C.

A typical example of a Proto Template is:

AssemblyOfIndividualTriple(x, y, z)  AssemblyOfIndividual(x)  ArrangementOfIndividualTriple(x, y, z)

AssemblyOfIndividualTemplate(y, z)  ∃u(AssemblyOfIndividualTriple(u, y, z))

The full list is shown here.

meta - Part 6 Meta Data

In ISO 15926-6 an ontology for meta data has been introduced. In OWL terms these are instances of owl:AnnotationProperty. These meta data describe provenance data about objects and templates, not about their information content.

rdl - Reference Data Library

The Reference Data Library includes the Part 4 Reference Taxonomy and the Part 8 Reference Ontology.

Part 4 Reference Taxonomy

The Reference Data (in this definition) are, at present, mostly represented as a taxonomy. A definition for taxonomy is:

A taxonomy refers to either a hierarchical classification of things, or the principles underlying the classification. Almost anything, animate objects, inanimate objects, places, and events, may be classified according to some taxonomic scheme.

A typical example for a listing in the RDL (Reference Data Library) in RDF, according ISO 15926-8 Annex E, is (in Turtle):

rdl:RDS416834 rdf:type dm:ClassOfInanimatePhysicalObject, owl:Class ;

    rdfs:subClassOf rdl:RDS432584 ; # DYNAMIC PUMP

    rdfs:label "CENTRIFUGAL PUMP" ;

    rdl:definition "A dynamic pump that contains impellers provided with vanes to generate centrifugal force to achieve the required pressure head." ;

    meta:valEffectiveDate "1999-07-01T00:00:00Z"^^xsd:dateTime ;

Part 8 Reference Ontology

Here specialized instances of the templates in the tpl ontology are stored. These templates refer to the reference data (concepts) in the Part 4 Reference Taxonomy.

See here for an example.

Future Part 12

dmno - Part 12 ISO 15926 in native OWL

A group of OWL specialists in PCA (the POSC Caesar Association) is working on expressing ISO 15926 in native OWL, as was indicated in Part 8 Annex C.  As it stands now ISO 15926 as described on this website is using OWL DL, be it for lowered templates. Part 12 will address the lifted templates.

tno - Part 7 Lifted templates in native OWL

In each Template Specification a listing in FOL, First-order Logic, is included, defining the lifted version of the specified template.

Although this is too early to say, it would be appropriate in case the FOL would be mapped to that ISO15926-in-native-OWL-to-come. In that case it would be conceivable to use this ono ontology to define the rdl ontology, instead of the tpl ontology (that tpl ontology would be indirectly used anyway).

Extensions of the RDL defined by organizations

org - Organization Reference Data Library

The Organization Reference Data Library is a combination of:

  1. The Organization Reference Taxonomy, an extension of the Part 4 Reference Taxonomy, in which a user organization can store user-specific specializations of dm:Classes in the Reference Taxonomy. Examples are:
    • Product models of a supplier, as shown in his catalog;
    • Product specifications of industrial standardization organizations, such as ASME, DIN, etc
    • Corporate standards, such as for formats of tag numbers, document types, pipe specifications, paint specifications, etc.
  1. The Organization Reference Templates, is an extension of the Part 7 Reference Ontology, in which a user organization can store user-specific specializations of templates in that Reference Ontology. Examples are:
    • Specialized templates specific for product models of a supplier, as shown in his catalog;
    • Specialized templates specific for product specifications of industrial standardization organizations, such as ASME, DIN, etc

It is also possible to store translations of texts in a natural language other than English. These may stay in this Organization Ontology, or be offered to ISO for inclusion in the Reference Ontology.

Lifecycle Information and reference data

xyz - Lifecycle Information

The Lifecycle Information store contains instances of entity types and templates in RDF format:

  1. declared instances of Part 2 entity types;
  2. declared instances of tpl:Template, that are specializations of the OWL template classes in the RDL, or extensions thereof.

These instances are the result of mapping data residing in a COTS application, where only those data that originated there are being mapped.

Corporate Reference Ontology

xyzont - Reference data in OWL2, for reasoning

The org - Organization Reference Data Library is mapped to OWL2 format to support reasoning. The degree of mapping may be determined by the objects that are in the discourse of reasoning.

Project data, mapped to OWL, for reasoning

xyzowl - Project Data ontology


Normally project data are being stored in RDF format, using SPARQL as query language. But in case OWL reasoning needs to be done, a "domain of discourse", a subset of the RDF data, is selected with SPARQL and mapped to OWL.