Quiz Entry - updated: 2026.07.14
What are the key elements of a Use Case description table?
Name, Actor, Purpose, Preconditions, Postconditions, the numbered Normal Flow, and Extensions (alternative/error flows) — the text companion to a use-case diagram.
A use-case diagram shows the bubbles; a use-case description table writes out one bubble in full so it can be implemented and tested.
Use Case Table Structure:
| Element | Description |
|---|---|
| Name | Use case identifier (e.g., "Peer-to-peer payment") |
| Actor | Who performs the action (e.g., the end user) |
| Purpose | What the use case accomplishes |
| Precondition | Conditions that must hold before it can run |
| Postcondition | System state after it succeeds |
| Normal flow | Numbered steps of the successful run |
| Extensions | Alternative flows and error handling |
Example normal flow — paying a friend phone-to-phone:
- User opens the mobile payment app.
- User picks the peer-to-peer payment method.
- User selects the recipient's phone number.
- App sends the payment details to the backend.
- Backend checks that the funds are available.
- Backend sends a payment update back to the app.
- User confirms; the app sends an OK to the backend.
- Backend books the payment to the recipient.
- Backend notifies both parties.
Tip: the numbered flow is the happy path; everything that can go wrong (insufficient funds, recipient not found) belongs in Extensions, referenced by step number.