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According to the OWL 2 Web Ontology Language Document Overview (Second Edition), the primary exchange syntax for OWL 2 is RDF/XML. Therefore, every IOF ontology MUST be serialized in the RDF/XML syntax, using more specific rules explained in the subsequent sections.

Base IRI

According to TBD, the xml:base attribute of an XML element determines an IRI prefix to be prepended to every relative IRI used in any nested XML element. For example, the following provides a fictitious example of how this mechanism works:

<?xml version="1.0" encoding="UTF-8"?>                  
<!DOCTYPE rdf:RDF [
        <!ENTITY bfo "http://purl.obolibrary.org/obo/">
]>      
<rdf:RDF xml:base="https://spec.industrialontologies.org/ontology/core/Core/"
        xmlns:bfo="http://purl.obolibrary.org/obo/"
        xmlns:iof-core="https://spec.industrialontologies.org/ontology/core/Core/"
        xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>
  <owl:Class rdf:about="AgentRole">
    <rdfs:subClassOf rdf:resource="&bfo;BFO_0000023"/>
  </owl:Class>
</rdf:RDF>

The value of the rdf:about attribute on line 10 would be appended to the xml:base attribute provided on line 5 to yield the IRI https://spec.industrialontologies.org/ontology/core/Core/AgentRole.

In order to ensure that the correct IRI is prepended to the value of every relative IRI in an IOF ontology, the xml:base attribute of the rdf:RDF XML element MUST have the ontology IRI as its value.

Default Namespace

Appendix

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