If the UML element is used in more than
one diagram, then you will see the UML Editor diagram name at the root
of the UML element.
In this example actor is the same UML element and is used in two
different diagrams (e.g.
pUseCaseDiagram and pUseCaseDiagram_1)
If you double click on
the eannotation representing the UML diagram, then you will open the
associated UML Editor diagram.
In this example the double click will open the component diagram (you can notice that the
icon is depending on the type of diagram)