Anonymous union class

Ontology(<http://nomagic.com/ontology/example-case/case-26>
      Declaration(
             Class(:Cat)
      )
      Declaration(
             Class(:Dog)
      )
      Declaration(
             Class(:Person)
      )
      Declaration(
             ObjectProperty(:caredForBy)
      )
      Declaration(
             ObjectProperty(:caresFor)
      )
	  AnnotationAssertion(rdfs:label :Cat "Cat"@en)
	  DisjointClasses(:Cat :Dog)
	  AnnotationAssertion(rdfs:label :Dog "Dog"@en)
	  AnnotationAssertion(rdfs:label :Person "Person"@en)
	  AnnotationAssertion(rdfs:label :caredForBy "cared for by"@en)
	  InverseObjectProperties(:caredForBy :caresFor)
	  ObjectPropertyDomain(:caredForBy ObjectUnionOf(:Dog :Cat))
	  ObjectPropertyRange(:caredForBy :Person)
	  AnnotationAssertion(rdfs:label :caresFor "cares for"@en)
	  ObjectPropertyDomain(:caresFor :Person)
	  ObjectPropertyRange(:caresFor ObjectUnionOf(:Dog :Cat))
)