export to TTL adds classes and labels to the ontology

[javadch]

I upload and visualize an ontology that only contains the following:
:Observer rdf:type owl:Class;
rdfs:comment "An agent that can observe an observation"@en ;
rdfs:label "Observer"@IRI-based;
rdfs:label "Observer"@en .

:observes rdf:type owl:ObjectProperty ;
rdfs:comment "The observes property gives the observations that have been observed by an observer." ;
rdfs:label "observes"@IRI-based;
rdfs:label "observes"@en;
rdfs:domain :Observer;
rdfs:range oboe:Observation .

Then I export it to TTL without any other modification. It generates the following output:

:observes rdf:type owl:ObjectProperty ;
rdfs:comment "The observes property gives the observation that has been observed by an observer." ;
rdfs:label "observes"@IRI-based;
rdfs:label "observes"@iri-based;
rdfs:label "observes"@en;
rdfs:domain :Observer;
rdfs:range oboe:Observation .

oboe:Observation rdf:type owl:Class;
rdfs:label "Observation"@IRI-based .

:Observer rdf:type owl:Class;
rdfs:comment "An agent that can observe an observation" ;
rdfs:label "Observer"@IRI-based;
rdfs:label "Observer"@iri-based;
rdfs:label "Observer"@en .

Here:

• the oboe:Observation class statement must not be created. It is neither defined in the original ontology nor needed to be there.
• It generates an additional @IRI-based label for existing classes and properties. The existence of @IRI-based or @iri-based does not affect this behavior. However, it generates only @IRI-based for oboe:Observation (that was not supposed to be in the ontology at first place.)