assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:4607  oio:id           DOID:4607  xsd:string  
1          0           graph  DOID:4606  rdfs:subClassOf  DOID:4607  _IRI        
1          0           graph  DOID:3121  rdfs:subClassOf  DOID:4607  _IRI