Add Extensions to Use Case Steps

As implied by the name, the “main success scenario” describes the steps that are taken most of the time and when nothing goes wrong. In order to enter an alternate flow of events or an exception, add an extension to a step. Right-mouse click on the use case step to which you want to add the extension and choose Add Extension from the context menu (Shortcut : press Ctrl-E to add an extension to the use case step where the editing caret is located).

add extension


Each extension should start with a verifiable condition describing the circumstances that trigger this extension, and a list of steps that are taken:

extension details

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  • Avatar
    Beau Frazer

    Is there a statement that will link the extension back to the success guarantee? I note in the example above there is prose to say that the use case terminates, is this the correct statement or just an example?

  • Avatar
    Doug Earl

    Hi Beau,
    Yes, certain statements have special meaning when they appear in the last step of an extension. For example, if a step number is found anywhere in the step's text (doesn't matter what the text says), such as Continue at step 4, CaseComplete will keep the number in sync with the referenced step as steps are added, removed, and reordered. If the step ends with one of several keywords, such as terminates, ends, or finishes, the termination shape is used on an activity diagram. Same is true for a step number (a red numbered icon is used). Learn more about activity diagrams and see examples here.

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