A junction point can merge and/or split several input and output transitions. It is similar to the decision in the activity diagram
A junction point can be created in the following diagrams:
You are not allowed to use shortcuts of a junction point. A junction point may be dependent on event parameters if the parameters include some split or merge variables for example.
You can attach two transitions of opposite directions to the same junction point symbol.
The symbol of a junction point is an empty circle: