assertion  retraction  graph  subject    predicate        object    datatype    annotation
1          0           graph  DOID:633   rdfs:subClassOf  DOID:423  _IRI        
1          0           graph  DOID:423   oio:id           DOID:423  xsd:string  
1          0           graph  DOID:9884  rdfs:subClassOf  DOID:423  _IRI