Recently I was asked to advise on the requirements capture process for an organization wanting to apply agile techniques in a controlled environment. I came up with some slightly different names for types of requirement, though I think the concepts will be familiar to you if you've analyzed other software development methods. The requirements types (shortened to PCF) are as follows:
- Business problem statements (Problems)
- Solution contraint statements (Constraints)
- Solution feature statements (Features)
Problems, for example, should identify issues in terms of a measurable aspect of the current solution and the degree to which a performance improvement would overcome it. Constraints express aspects of the solution that the current designers are not expected to change (though they should also state the rationale behind the constraint, and how and by whom it may be changed if justification exists). Only by considering all of these three types of requirement can the essential requirements of a system be captured.