So I have an association class C that is an association between classes A and B. Class D is a subclass of class C as it contains data from class C. Is it possible? and can it be represented as a diagr...

I have this diagram. The staff receives an email when his letter is approved. Do I need add an include relationship between two use cases? If I did that, it means the staff needs to approve letter to ...

I have created two sequence diagrams and I wanted to reference one of them in the other, I know to do that we have to use interaction use, but I can't write on it or reference the other sequence diagr...

What the difference between a self message and a return message. Here 2 examples: Self Message: Return Message: Which example is correct?