diff --git a/src/cco-modules/ExtendedRelationOntology.ttl b/src/cco-modules/ExtendedRelationOntology.ttl
index 921d684..71538cd 100644
--- a/src/cco-modules/ExtendedRelationOntology.ttl
+++ b/src/cco-modules/ExtendedRelationOntology.ttl
@@ -547,6 +547,8 @@ cco:ont00001928 rdf:type owl:ObjectProperty ;
 cco:ont00001933 rdf:type owl:ObjectProperty ;
                  rdfs:subPropertyOf cco:ont00001803 ;
                  owl:inverseOf cco:ont00001962 ;
+                 rdfs:domain obo:BFO_0000015 ;
+                 rdfs:range obo:BFO_0000015 ;
                  rdfs:label "process starts"@en ;
                  skos:definition "x process_starts y iff x and y are instances of processes, and x is_cause_of y, and i is an instance of a temporal instant, and r is an instant of a temporal interval, and y has starting instance i, and x occurs on r, and r interval contains i."@en ;
                  skos:scopeNote "A process x starts another process y when x causes y while x is still occurring."@en ;