The namespace block must
indicate all the prefixes and namespaces used in the model.
The metadata block must
contain the actual annotation property elements, aliases are not
allowed. For instance, the user should type owl:versionInfo instead of "version"
to indicate the current version of the ontology.
The source and target of all the arrows in the diagram are connected to a block. This means that
relationships between properties (e.g. rdfs:subPropertyOf) can only use the
to being able to generate them in OWL code.