UMLR — Arguments of Message

3. Arguments of Message
Variables, members and other "value holders" can be used as arguments of call actions or arguments of message (for example setName(name) where "name" is variable defined in Interaction), but now arguments are simple ValueSpecification, so can't have reference to "real" argument (variable, member, parameter of behavior etc.)
Maybe Argument should be in metamodel as in UML 1.4, or at least ValueSpecification should be subclassed in Interactions package and introduce reference to Element that value it represents?