Deciding: Requirement or Exclusion
After you have gathered needs, categorize them as either requirements or exclusions. In effect, you are deciding to:
Documented requirements must be clear and concise, because they form the basis of your project plans. As you write requirements, determine whether they can be misinterpreted. Writing requirements that can't be misinterpreted is a difficult task. To help ensure that requirements are clear, include graphics, models, and other visual representations, where appropriate.
After you have written the requirements document, ask your team to review it to be sure they have the detail they need to get started.