It is not uncommon for systems analysts, software developers
and architects to produce series of documentation during all the phases of software
development life cycle. We call these documents by many names. Business
Requirement Document (BRD), System Requirements Specification (SRS), Functional
Requirements Specification (FRS), System Design Documents (SDD) and Technical
Design Document (TDD) are some examples. Many people and organization call
these documents by various names; but they more or less serve the same purpose.