A full set of use case diagrams shows all the procedures available for interaction with the system. It is a summary of system functionality. Despite arrows on the diagrams they do not show any kind of procedures or data flow, only what procedures are available and how they are grouped by actor.
|Show the grouping of services provided by the system to the actors|
|Create as many diagrams as are needed to cover all the functionality of the system|
|Size the diagrams for readability on a computer screen or page|
|Include all actors and use cases on at least one a diagram|
|Diagram contents may overlap but don't repeat actors or use cases on the same diagram|
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