Referring to steps of the main success scenario

Sometimes you want to refer from an extension step (or another main success scenario step) to a particular step of the main success scenario.

In such a case, use a step-ref element:

<use-case goal="Transfer funds" code="NCA-100">
        <success>
                <step handle="debit">User identifies debit account.</step>
                <step handle="credit">User identifies credit account.</step>
                <step>User enters amount.</step>
                <step>User submits the transaction.</step>
        </success>
        <extensions>
                <condition step-ref="credit" when="Debit and credit accounts are the same">
                        <step>System displays error message
                                and returns to step <step-ref handle="debit" />.</step>
                </condition>
        </extensions>
</use-case>

In the above example the text within the extension condition refers to the step of the main success scenario with handle "debit" using <step-ref handle="debit" /> element. This element will be replaced by the number of the referred step in the HTML output.

So, in our example, the output text of the condition will be "System displays error message and returns to step 1.".

Such reference mechanism provides for addition of new steps into the use case without the need to manually re-number all such references. In UCTool, they get re-numbered automatically.