assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:6404  rdfs:subClassOf  DOID:2697  _IRI        
1          0           graph  DOID:2697  oio:id           DOID:2697  xsd:string  
1          0           graph  DOID:6257  rdfs:subClassOf  DOID:2697  _IRI