| Feature | Category 3 (Non-Configured) | Category 4 (Configured) | Category 5 (Custom) | | :--- | :--- | :--- | :--- | | | Low priority (usually certificate review). | Recommended to verify supplier quality. | Critical (or rigorous internal development QA). | | Specifications | URS only (mostly). | URS + Functional Specs (Configuration). | URS + Functional + Design Specs. | | Source Code | Not reviewed. | Not reviewed. | Mandatory Review. | | Unit Testing | N/A (Done by vendor). | N/A (Done by vendor). | Required. | | Testing Focus | Functional use cases. | Configured workflows & security. | Code logic, paths, and functionality. |