------->	Enter Order
				| \/
		| \/		| \/	*[for each	orderline]
Cancel Order	[failed] <-------	Verify Payment		Check Item	[out of stock] ----------->	Hold Order
		| |		| \/	[in stock]
[suc	ceeded]	| |		Assign to Order
		| \/		| \/
		[all items assigned and payments verified]		| | | | \/
				Dispatch Order

There are other cases in which an activity may not have a next activity, because the following activities may not have a sequence so can be accomplished in any order. These activities could be happening in parallel. In this case, you will need to use a synchronization bar (a heavy horizontal bar) to connect the activities. In Figure 6-4, after the Assign to Order activity, the next activity can be Dispatch Order and/or Reorder Item because they are independent activities. Synchronization bars are also used to bring together parallel processes.

You can also create parallel activities by having a multiple trigger; indicate on the diagram the basis of the trigger. If you use a multiple trigger, then you must remember to synchronize the parallel activities with the synchronization bar.

Follow these steps to create an activity diagram:

1. Select a use case.
2. Add activities to the diagram.
3. Add triggers.
4. Add guards, if necessary.
5. Add synnchronization bars, if necessary.