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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 in every ontology file MUST have the ontology IRI as its value.
Default Namespace
Every IOF ontology MUST NOT declare a default namespace to ensure that no XML element is inadvertently put into the wrong namespace.
According to TBD, the default namespace of an XML element determines the namespace of every nested XML element that does not have an explicit namespace. The following provides an example that is technically legal, but disallowed by this policy:
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