SST Ontologies

SST comes with a set of pre-defined higher level ontologies. These are in hierarchical order (together with the standard used prefix):

• the basic Ontologies as defined by the W3C Semantic Web are:
  • RDF(rdf) and RDFS(rdfs) for the basic concepts such as Triple, NamedGraphs, Datasets and more
  • OWL 2(owl) for the logical layer
  • common datatypes defined in XML-Schema(xsd)
  • SKOS(skos), the Simple Knowledge Organization System Reference
  • SHACL(sh), the Shapes Constraint Language to define data model constraints; no yet implemented
• the fundamental ontologies that are application independent are on top of the basic ontologies:
  • SSMETA(ssmeta) to direct the SST-Core on how to operate
  • LCI(lci) “Live Cycle Integration” that is derived from the ontology defined in ISO/TS 15926-12 to support the concepts defined in the data model of ISO 10303-2
  • Quantities & Units(qau) as defined in ISO 80000
• the STEP related ontologies and other application oriented ontologies are on top of the fundamental ontologies:
  • all STEP definitions on Representation(rep), based on ISO 10303-43 and many other parts out of the ISO 10303 series of standards. This includes geometry, topology, presentation & styling, kinematics and others
  • STEP PDM(sso) – Product Data Management – concepts that are primarily extracted from the Domain Model of STEP AP242 as defined in ISO/TS 10303-4442 “Managed model-based 3D engineering domain”
  • Schematic Diagrams(eed)
• Reference data ontologies
  • IEC Common Data Dictionary as defined in IEC 61360 (draft)
  • … more reference data sources to be added over time

The SST ontologies form a single level data mdel.

Not for any particular business case

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Typically data-models are created to support a well specified business case - or a few related ones. This is not been the case for the SST-Ontologies. The focus is here to describe the nature of things around us; those we can touch and also those we can imagine, covering the past, presence and future.

Properties as first class citizens

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Typically it is said that RDF triples are used to represent a graph with the subjects and object as the graph nodes and the predicates as the graph edges. In this model the RDF properties that are used for the predicates are defined in special higher level ontologies and there is a limit number of them. Application data are not defining any new RDF properties but only using the ones in the upper level ontologies as predicates in triples. This concept is similar to traditional modelling concepts such as Express (ISO 10303-11) and UML/SysML where application data can defines instances of the defined entities/classes, but are not allowed to define “instances” of properties.