2. Requirements Fulfilment

	Developers and testers work to satisfy the requirements exactly. They have no discretion in this matter. They cannot improve or change the requirements in any way. One of the roles of the testers is to ensure the developers are correctly addressing the requirements.

3. Requirements Evaluation

	Managers, often in continuing consultation with the client, evaluate the system and the requirements, and make changes to either where necessary. This process may be ongoing, leading to iterative development.