assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:2519  oio:id           DOID:2519  xsd:string  
1          0           graph  DOID:2998  rdfs:subClassOf  DOID:2519  _IRI        
1          0           graph  DOID:3579  rdfs:subClassOf  DOID:2519  _IRI