Documenting high-level requirements

At the beginning of a project, not much is truly known about the ins and outs of the scope of work, what things will actually cost, and how long the project will actually be. Yes, it is predictive, but it's tough to predict everything at this point. That is why high-level requirements are made and agreed upon, and also why all projects are progressively elaborated on. Progressive elaboration is a fancy term for going with what you know today and expanding on that knowledge once you can. Elaborate progressively on scope, time, and cost, as well as risk, quality, and resources.

For example, we are planning to build a new data center in Scottsdale, Arizona. Predictive means we know we are building a data center, we know where it will be built, and we know how long the last data center took to build and what it cost (maybe). When we are finished, we will have a data center. So, the business case and benefits management plan is created, and the...