The functional requirements document (frd) is a formal statement of a product's functional requirements. A functional specification document (fsd), also known as a functional requirements document (frd), is considered by many project management and software. Are you wondering what a functional requirements document or what an frd is? Use the following priority table. It allows you to apply a ratings system to your requirements, so you have the visibility (into the value, status, and description of each requirement) that’s.