Functional documents for computer systems

Although software documentation standards often go into great detail about the format of documents, describing such details as paragraph numbering and section headings, they fail to give precise descriptions of the information to be contained in the documents. This paper does the opposite; it defines the contents of documents without specifying their format or the notation to be used in them. We describe documents such as the “System Requirements Document”, the “System Design Document”, the “Software Requirements Document”, the “Software Behaviour Specification”, the “Module Interface Specification”, and the “Module Internal Design Document” as representations of one or more mathematical relations. By describing those relations, we specify what information should be contained in each document