Should the `a owl:Ontology` triple be generated by SHACL-C without `BASE` keyword

[jeswr]

It is unclear in the SHACL-C spec whether the a owl:Ontology triple should be generated when the BASE keyword is not used.

Raised in this discussion solid/catalog#15 (comment)

[afs]

There is always a "base URI" -- https://datatracker.ietf.org/doc/html/rfc3986#section-5.1

BASE replaces the current base URI.

<> a owl:ontology . will work regardless of the presence of BASE or not.

[jeswr]

Thanks @afs - I was a bit unclear in the initial issue. My question was actually: should the ?baseURI rdf:type owl:Ontology triple always be generated when parsing a shaclc document; or is this conditional.

The following text which I'd missed before opening the issue seems to answer that question.

"""
Once the whole document has been completed, produce a triple ?baseURI rdf:type owl:Ontology using the final value of baseURI. Report an error if baseURI has no value but imports is not empty. For each iri in imports, produce a triple ?baseURI owl:imports ?iri.
"""

This does raise the follow up questions:

• It doesn't seem appropriate to always generate the triple ?baseURI rdf:type owl:Ontology. In SHACL-C 1.2 should we skip the generation of this triple - or make it opt-in using a keyword. It can be particularly annoying when using tools like rdf-transform to convert from ttl to shaclc as the tool (as I have currently implemented it) will error if there is no ?baseURI rdf:type owl:Ontology in the ttl document.
• Should "Report an error if baseURI has no value but imports is not empty." be removed from the text given that there is always a "base URI" -- https://datatracker.ietf.org/doc/html/rfc3986#section-5.1