assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:3709  rdfs:subClassOf  DOID:1996  _IRI        
1          0           graph  DOID:7707  rdfs:subClassOf  DOID:1996  _IRI        
1          0           graph  DOID:1996  oio:id           DOID:1996  xsd:string