Define software artifacts rigorously. Establish a software process that provides flexibility. In 40-20-40 rule, maintenance counts for one of the 40. Configuration items is also called the baselines. We should plan and manage to prevent changes and uncertainty. We should discuss Tradeoffs explicitly with the users, but no need to document them in baselines. Perfective maintenance adapts to changes in the environment (both hardware and software). Manage quality as informal as possible. Agile projects do less planning than document-driven projects that means documentation is not important at all. We should never through away a prototype, because we already spent money and time on it.