assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:6019  oio:id           DOID:6019  xsd:string  
1          0           graph  DOID:6018  rdfs:subClassOf  DOID:6019  _IRI        
1          0           graph  DOID:6654  rdfs:subClassOf  DOID:6019  _IRI