assertion  retraction  graph  subject    predicate        object     datatype    annotation
1          0           graph  DOID:4504  rdfs:subClassOf  DOID:2133  _IRI        
1          0           graph  DOID:2133  oio:id           DOID:2133  xsd:string  
1          0           graph  DOID:6451  rdfs:subClassOf  DOID:2133  _IRI