Break / Stop Execution In UML Sequence Diagram Mid-way Inside Alt / Opt
Answer : There are three options for this situation. Each of them I illustrate with a diagram showing how the respective combined fragment should be used. The actual behaviour is hidden with interaction references (normalFlow for a flow that should normally be executed and breakFlow for any flow that should happen in case of a required break). The first solution is the most convenient one - it exactly covers your case and you can also use the positive version of a break guard. However each of them provide you a valid possibility. Break combined fragment When a break combined fragment is met and its guard condition is true, only this fragment is still executed and then the execution of the interaction (flow) stops. If the condition is not met, the combined fragment is omitted and the normal flow continues. This is exactly the case you describe. In this case you would put the messages that shouldn't be executed in case of a break condition after the break combined fragment...