assertion  retraction  graph  subject    predicate        object    datatype    annotation
1          0           graph  DOID:2814  rdfs:subClassOf  DOID:833  _IRI        
1          0           graph  DOID:833   oio:id           DOID:833  xsd:string  
1          0           graph  DOID:5101  rdfs:subClassOf  DOID:833  _IRI