If you cannot identify the origin, perhaps the requirement is an example of gold-plating and isn t really necessary. Assign an implementation priority to each requirement, feature, or use case to indicate how essential it is to a particular product release. Customers or their surrogates have the lion s share of the responsibility for establishing priorities. If all the unprioritized requirements are equally important, so is the project manager s ability to react to new requirements added during development, budget cuts, schedule overruns, or a team member s departure. You can determine priority by considering the requirement s value to the customer, the relative implementation cost, and the relative technical risk of implementing it.
Many groups use three levels of priority.
High priority means you must incorporate the requirement in the next product release. Medium priority means the requirement is necessary but you can defer it to a later release if necessary. Low priority means it would be nice to have, but you might have to drop it because of insufficient time or resources. The reader of a requirement statement should draw only one interpretation of it. Also, multiple readers of a requirement should arrive at the same interpretation.