What is the purpose of the alternate flows in a use case?

The purpose of alternate flows in a use case is to illustrate the various paths that can be taken other than the main or primary flow toward achieving the goal. These alternate flows help to capture the different scenarios that might occur during the execution of the use case, offering a comprehensive view of how the system can behave under various conditions.

By detailing these alternate flows, the use case document ensures that all potential interactions are considered, providing clarity on how the system will handle situations that deviate from the expected norm. This assists in identifying edge cases, special conditions, or additional business rules that need to be refined during the system's development and testing phases.

Understanding alternate flows is essential for thorough requirement analysis and ensures a robust design that anticipates and accommodates user needs effectively. Different users or error conditions may be represented in these flows, but the essence of the alternate flow is capturing all possible pathways to reach the end goal beyond the primary interaction.