No Start Event

The BPMN standard allows processes with no Start Event. In this case, all Activities with no incoming Sequence Flows will be activated.

Anti-Pattern: 
Discussion: 

Processes are easier to understand if there is a clear start and a clear end. If there is more than one, the behavior is confusing to many business users. Some tools will not allow a process with no Start Event. In the diagram above, you can see that there are validation errors on each Activity. With no Start Event, there is no indication of what causes the process to be started.
The one exception to this rule is a sub-process with single Start and End points. In this case, the intent is clear.

Recommended Alternative: 

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