param elem element delet delet stimulu object elem elem stimulu illeg argument except elem elem stimulu stimulu stimulu elem delet interact instanc set particip stimulu iter omg uml uml stimulu ref outermost collabor interact instanc set particip stimulu interact instanc set stimulu iter interact instanc set ii interact instanc set collect instanc ii particip stimulu instanc size instanc contain elem model impl uml factori delet 