assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:6517  oio:id           DOID:6517  xsd:string  
1          0           graph  DOID:8239  rdfs:subClassOf  DOID:6517  _IRI        
1          0           graph  DOID:8221  rdfs:subClassOf  DOID:6517  _IRI