As a matter of fact, software evaluations are performed at different levels of detail. For example, when you screen the market for a suitable software product, you focus on coarse-grained requirements. You would create an RFP that contains only a limited number of critical requirements.

At this stage, you would concentrate on requirements that primarily address conceptual aspects, such as 'management', 'model' and 'pattern'. For example, it would be satisfying to ascertain that a software product fully supports user lifecycle management.

As you proceed to a more thorough evaluation, your focus will be more on fine-grained requirements. For example, you would add requirements on application programming interfaces, formats and protocols to your Evaluation Specification (which is a precursor to a Request for Proposal (RFP)).

Functional Requirements Packages (FRPs) contain requirements of different granularity. Thus, FRPs fit your needs if you perform a high-level evaluation and if a thorough low-level evaluation is planned.