Subject A can be any concept or entity outside of an ontology (or an ontology concept in a role of an entity being semantically annotated). Object B can either be a concept that is (or is in a role of) a function, or an entity outside of an ontology that is (or is in a role of) a function specification. In the scope of EDAM, 'has_function' serves only for relating annotated entities outside of EDAM with 'Operation' concepts.