A functional specification document (fsd), also known as a functional requirements document (frd), is considered by many project management and software. If you are unfamiliar with this document, do not be vexed. What is a functional requirements document? 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. This document underlies the functional requirements for implementing online banking solution (obs) for global bank ltd (gbl).