UMLR — Interactions and parameter assignments

is it intended to not let message arguments being assignable to attributes of the receiving lifeline?

As an example: Lifeline A sends a synchronous operation call to Lifeline B for the operation op(in x:Integer). Assume that the Type Lifeline B represents owns a Property p:Integer. The received actual parameter x shall be assigned to Property p of the receiving lifeline.

With the current semantics of Messages and its description for notation it is only possible to assign out/inout/return values to a receiving lifeline. Consider the case that a certain Lifeline receives a Signal (no out/inout/return parameter at all) and wants to store the value of an attribute of that Signal in an attribute (either of the surrounding Interaction or its context Classifier); this is not possible by default.

In my realm (which is validation and testing mainly using UTP), this is quite normal. A system under test (SUT) responds with a Signal and some values of that signal need to be stored for later calculation or re-sending.

Shall we allow this in Interactions?