In the context of use cases, what does 'extend' allow for?

The term 'extend' in the context of use cases refers to the ability to integrate additional scenario behavior that occurs under specific conditions. This means that an extending use case adds optional behaviors to a base use case without altering the original flow. The extension commonly occurs at points where certain conditions are met, allowing for changes in the execution path based on specific triggers or circumstances.

This concept is key in understanding how use cases can be reused and how they enable flexibility and scalability in system design. It allows the development team to maintain a clear base case while also accommodating variations and exceptional cases that may arise under certain conditions. By using the extend mechanism, stakeholders can clearly identify areas where additional functionality might be added without complicating the primary flow of the base use case.

This understanding highlights how use cases can be structured for growth and adaptation, ensuring that the original functionalities remain intact while allowing new features to be added contingent upon certain conditions being met.