Must ref frames in UML diagrams always be accompanied with an sd frame?

[exetr]

In a case where the logic abstracted by a ref frame is trivial and in order to simplify the diagram, would it be ok to exclude the accompanying sd frame?

[okkhoy]

My thinking: If it is so trivial, you probably don't need a ref frame. If you need a ref frame, it is probably not so trivial (is it?) If it is not so trivial, you need to say what happens in the ref frame, so needs an accompanying sd frame.

I would leave you to judge the appropriateness.

[exetr]

Thanks prof!