Documentation is a necessary point to be considered and we have stressed this at multiple places in the book. We won't be covering this in detail again, but it's important to maintain the relevant documentation, such as scope of work, functional documents, project plan, code comments, test cases, deployment document, and architecture document.

People change over time and having good documentation helps the people who weren't part of the project earlier to quickly get hang of the project and cater to newer needs of the business or modification in the existing project.

BI project also involves integration and customization, and these too should be clearly documented. Other documents which should be maintained are the QMC settings.