A functional requirements document (frd)—also known as a functional requirements specification, functional specification, or functional specification document—is a more. [provide a list of contractual or task level assumptions and/or constraints that are preconditions to preparation of the frd. They communicate what problem needs. Assumptions are future situations beyond the control of the project,. A user requirements document, written by the product manager, is centered around the end user’s needs and expectations for a product.it translates user requirements into.