assertion  retraction  graph  subject          predicate        object            datatype    annotation
1          0           graph  obo:CHEBI_37598  rdfs:label       nitrogen mustard  xsd:string  
1          0           graph  obo:CHEBI_37598  oio:id           CHEBI:37598       xsd:string  
1          0           graph  obo:CHEBI_37598  rdfs:subClassOf  obo:CHEBI_35352   _IRI        
1          0           graph  obo:CHEBI_37598  rdf:type         owl:Class         _IRI