Use case extensions define how to handle exceptions and alternate flows for a specific step in your use case. Some types of exceptions and alternate flows need to be trapped throughout the execution of a use case - those are called "anytime extensions" because they can happen - and must be handled - at any time through the use case.
To create an anytime extension, right-mouse click on the use case flow of events. Choose Add Anytime Extension from the context menu (Shortcut : press Alt-E to add an extension to the use case step where the editing caret is located).
When you add an anytime extension, it is labeled with an asterisk (rather than a specific step number) to indicate that it can be triggered any time.
For example, if you know the network can go down at any time, you could add this as an anytime extension:
This is a helpful comment. I actually think that calling it an "anytime extension" is confusing though. I thought it was for an extension that could be used repeatedly within one use case or in multiple use case for that matter.
Thanks for the feedback!
We heavily referenced a couple of books when creating CaseComplete,
Advanced Use Case Modeling, Frank Armour and Granville Miller, Addison-Wesley, 2001
Writing Effective Use Cases, Alistair Cockburn, Addison-Wesley, 2001
and Alistair's book states on page 103, "If the condition can occur at any time, use an asterisk (*) instead of the step number."
So, we used the word Anytime to refer to these types of extensions. Hope this helps.