Ontology File Formats¶
General¶
The registry for ITS ontologies (RITSO) intends to capture ontologies for ITS documented in widely accepted file formats that can be managed with a modern version control system and that can easily be translated into a website, including diagrams showing key references. The following technologies have been selected to achieve this management:
- GitHub: for version control
- Web Ontology Language (OWL): for specifying the semantics of the ontology
- W3C Turtle (.ttl) file format: for formally specifying OWL content. Alternative formats include RDF (.owl) and ontology functional syntax notation (*.ofn).
- The python scripts developed by this registry effort: to convert the ontology files into more human-friendly source files
- GraphViz: to convert the text description of graphics into actual graphics
- Material for MkDocs: to convert the source files into a website
Namespaces¶
Every ITS ontology should declare the following namespace prefixes:
- : (i.e., the default) typically the ontology namespace
- cc: http://creativecommons.org/ns#
- dcterms: http://purl.org/dc/terms/
- owl: http://www.w3.org/2002/07/owl#
- dash: http://datashapes.org/dash# (when used)
- rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#
- rdfs: http://www.w3.org/2000/01/rdf-schema#
- skos: http://www.w3.org/2004/02/skos/core#
- vann: http://purl.org/vocab/vann/
- xml: http://www.w3.org/XML/1998/namespace
- xsd: http://www.w3.org/2001/XMLSchema#
In addition, ITS ontologies should declare a namespace prefix for each additional ontology referenced. Even if the prefix is not used in the ontology file, declaring the prefix allows the diagrams that are generated by the python scripts to shorten the IRI to just the prefix to make diagrams more readable. The prefixes should use the preferred prefix for the referenced ontology (when declared) and it does not cause a conflict. Ideally, ITS ontologies should only reference ontologies already included in the RITSO.
Recommended Annotations¶
The RITSO recommends using the following annotations when describing ontologies.
| Annotation | Rationale and Usage Notes |
|---|---|
dcterms:title |
The name of the resource. |
skos:definition |
Definition; only once per language. If not present, script uses dcterms:description as fallback. |
vann:preferredNamespaceUri |
Although shown elsewhere, this is needed for some tools to pair with the preferred prefix. |
vann:preferredNamespacePrefix |
The preferred prefix to use when referring to items in this resource. |
dcterms:creator |
Primary author; can be more than one. |
dcterms:created |
Date of creation of the ontology file. |
owl:versionIRI |
The version of the ontology represented by this resource using semantic versioning. |
owl:priorVersion |
The date of the official preceding version of the ontology. |
dcterms:license |
Identifies the legal usage terms; CC-BY 4.0 is recommended. |
While the RITSO allows the use of any defined annotation, the following are recommended as preferred optional annotations to be used as appropriate for ontologies.
| Annotation | Rationale and Usage Notes |
|---|---|
dcterms:bibliographicCitation |
Provides the textual identifier of the document that formalizes or explains this ontology. |
dcterms:contributor |
Contributor to the ontology for which credit is to be provided. |
dcterms:issued |
Year that the associated document was formally issued. |
dcterms:modified |
Identifies the date of an update date; pair with repeatable skos:changeNote for descriptions. |
rdfs:seeAlso |
Provides the URI of the document that formalizes or explains this ontology. |
skos:changeNote |
Provides a description of the update date; pair with dcterms:modified |
The RITSO recommends using the following annotations when describing ontology elements (e.g., classes and properties).
| Annotation | Rationale and Usage Notes |
|---|---|
skos:definition |
Normative definition of the entity. Use no more than once per language. |
The RITSO recommends using the following annotations when describing ontology elements (e.g., classes and properties), as needed.
| Annotation | Rationale and Usage Notes |
|---|---|
dash:abstract |
Indicates that the class is not intended for direct instantiation. |
dcterms:created |
For creation date; if different than the ontology creation date. |
dcterms:isReplacedBy |
Identifies a new element that replaces a historic element; repeatable if needed. Inverse of the above |
dcterms:modified |
Date of an update; pair with repeatable skos:changeNote |
dcterms:replaces |
Identifies a historic ontological element that is replaced by a new ontological element; repeatable if needed. |
its-core:pii |
Boolean (true for personally identifiable information) |
owl:deprecated |
Boolean (true for deprecated/obsolete) |
rdfs:label |
Allows language-specific labels that can change with backward compatibility |
skos:changeNote |
Provides a description of the update date; pair with dcterms:modified |
skos:example |
Illustrative example; can use multiples. |
skos:note |
Informative details as needed; can use multiples. |