Semantic conventions

Formal language choice

Title: Formal language choice

Identifier SC-R1

Statement:

The formal ontology shall be expressed in OWL 2.

Checkable: Yes, partially

There is no specific signature of an OWL ontology other than its resources. At a fundamental level, if there is no ontology declaration, it can be an RDF-S ontology. For this assumption to hold true, it is expected that all resources have a type declaration. Any other aspect of the validity of an OWL ontology falls within the domain of its syntax, which is beyond the scope of the conventions.

SC-R2 has overlap.

Named instance of the ontology

Shapes File: only_owl_ontology.shacl.ttl

Shape Description(s):

  • A node shape targeting a dummy focus node with a custom SPARQL query that checks if there does not exist a statement with rdf:type.

    • Non-Compliance Severity: Violation

    • Non-Compliance Message(s):

      • Violation of standard practice: Missing explicit type declaration

  • A node shape targeting the focus node owl:Ontology with a restriction of minCount=1 and maxCount=1 on the inverse of the path rdf:type (i.e. there must exist exactly one instance of the ontology).

    • Non-Compliance Severity: Violation

    • Non-Compliance Message(s):

      • Violation of SEMIC rule SC-R1: Missing OWL ontology declaration

Limited (OWL 2) expressivity

Title: Limited (OWL 2) expressivity

Identifier SC-R2

Statement:

The formal ontology shall be lightweight in its logical underpinning, focusing mainly on the concept declarations, generalisation axioms and annotations.

Checkable: Yes, partially, with multiple derived subrules for best practices

No domain or range declarations

Shape File: no_domain_range_opt.shacl.ttl

Shape Description(s):

  • A node shape targeting any subject of rdf:type with restrictions of maxCount=0 on the properties rdfs:domain and rdfs:range.

    • Non-Compliance Severity: Warning

    • Non-Compliance Message(s):

      • Non-observance of SEMIC rule SC-R2: No expressions of property domain shall be used

      • Non-observance of SEMIC rule SC-R2: No expressions of property range shall be used

Limited OWL resource types

Shapes File: only_owl_resources.shacl.ttl

Shape Description(s):

  • A node shape targeting any subjects of rdf:type with a restriction on the property rdf:type having values only from the set {owl:Ontology, owl:Class, owl:DatatypeProperty, owl:ObjectProperty, owl:AnnotationProperty}.

    • Non-Compliance Severity: Violation

    • Non-Compliance Message(s):

      • Violation of SEMIC rule SC-R2: Only limited OWL class and property declarations shall be used

Overlaps with SC-R1.

Only OWL subsumption relationships between resources

Shapes File: only_owl_resources.shacl.ttl

Shape Description(s):

  • Node shapes targeting classes from the set {owl:Class, owl:ObjectProperty, owl:DatatypeProperty} with a custom SPARQL query that checks if there exists any property between two resources (the target and an IRI) that is not one of the set {rdf:type, rdfs:subClassOf, rdfs:subPropertyOf}.

    • Non-Compliance Severity: Violation

    • Non-Compliance Message(s):

      • Violation of SEMIC rule SC-R2: Only subsumption OWL class relations shall be used

      • Violation of SEMIC rule SC-R2: Only subsumption OWL property relations shall be used

Limit expressions to a select few properties

Shape File: select_few_expressions.shacl.ttl

Shape Description(s):

  • A closed node shape (ignoring basic properties which are the subject of other rules/shapes) targeting the class sh:NodeShape with several property shapes representing a limited recommended set, with only the property path declared for each.

  • *Non-Compliance Severity: Info

    • Non-Compliance Message(s):

      • Non-observance of SEMIC rule SC-R2: The ontology shall be limited to a select few expressions

Minimum ontology header

*Shape File: min_ontology_header.shacl.ttl

Shape Description(s):

  • A node shape targeting the class owl:Ontology with a property restriction of minCount=1 for each property from a limited recommended set (combining the list from the conventions and those used in a reference ontology ePO), and corresponding datatype restrictions (rdf:langString for those expected to be language-tagged, xsd:date for dates, sh:IRI for IRIs and xsd:string otherwise).

    • Non-Compliance Severity: Warning

    • Non-Compliance Message(s):

      • Non-observance of SEMIC rule SC-R2: The ontology shall include a minimum header ({?property} <{?type}>)

No advanced OWL constructs

Shape File: no_advanced_definitions.shacl.ttl

Shape Description(s):

  • A node shape targeting all subjects of rdf:type with a property restriction on an alternativePath list that includes a set of advanced OWL properties, and another similar shape with only the subsumption properties restricted to sh:IRI node kind (effectively forbidding use of blank nodes as values through those properties).

    • Non-Compliance Severity: Violation

    • Non-Compliance Message(s):

      • Violation of SEMIC rule SC-R2: Advanced logical definitions shall not be used

      • Violation of SEMIC rule SC-R2: Advanced logical definitions shall not be used (bNodes in subsumption)

Lexicalisation

Title: Lexicalisation

Identifier SC-R3

Statement:

The choice in handling the lexicalisation of concepts shall be clearly defined and consistently implemented.

Checkable: Yes

At least one of two primary lexicalisations

Shape File: min_one_lexicalisation_opt.shacl.ttl

Shape Description(s):

  • A node shape targeting any subjects of rdf:type with restrictions of minCount=1 on the UNION of the properties from the set {rdfs:label, skos:prefLabel}.

    • Non-Compliance Severity: Warning

    • Non-Compliance Message(s):

      • Non-observance of SEMIC rule SC-R3: At least one lexicalisation label should exist

At most one value per lexicalisation

Shape File: max_one_label.shacl.ttl

  • Non-Compliance Severity: Violation

  • Non-Compliance Message(s):

    • Violation of standard practice: More than one `skos:prefLabel exists without a language tag`

    • Language {lang} has been used by {n} values (default SHACL message)

    • Language {?lang} used more than once (default SHACL message)

Reasoning assumption

Title: Reasoning assumption

Identifier SC-R4

Statement:

No reasoning capabilities shall be assumed.

Checkable: No

Informational rule, actionable by way of other rules (e.g. SC-R2 No advanced OWL constructs).

Circular definitions

Title: Circular definitions

Identifier SC-R5

Statement:

The data specification (semantic, conceptual, or shape) shall not use circular definitions.

Checkable: No

A self-reference is not easy to check for without the use of custom SPARQL queries (that can inflate validation time) or resorting to non-standard approaches (e.g. dash:nonRecursive). Deferred for implementation in a later revision.