Product requirements review, capturing all the features/functions of the product:

• Re0: High level requirements
• Re1: Design/development level product requirements (linked to above step, Re0)
• Re2: Test/verification level product requirements (linked to above steps, Re0, Re1)
• Re3: Manufacturing/assembly level product requirements (linked to Re0, Re1)

Requirements will change through the development cycle on as-needed bases (Re0, Re1, Re2, Re3). This stage of PLM will keep/monitor the relationship to make sure all the steps are still taken to accomplish the high level requirements (Re0).