A start is a starting point of the flow represented in the diagram, and an end is a termination point of the flow.
Starts and ends can be created in models targeting any language except DFD.
In decomposed processes, only one start is allowed per diagram, except for analysis business process diagrams. The Start tool is unavailable if a start symbol already exists. You should not use the same start in two diagrams, and you cannot create shortcuts of starts.
You can create several ends within the same diagram to show divergent end cases, such as error scenarios:
If there is no end, the diagram contains an endless process. However, a decomposed process must always contain at least one end.