assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:2723  oio:id           DOID:2723  xsd:string  
1          0           graph  DOID:2773  rdfs:subClassOf  DOID:2723  _IRI        
1          0           graph  DOID:8502  rdfs:subClassOf  DOID:2723  _IRI