Precise documentation of well-structured programs

Describes a new form of program documentation that is precise, systematic and readable. This documentation comprises a set of displays supplemented by a lexicon and an index. Each display presents a program fragment in such a way that its correctness can be examined without looking at any other display. Each display has three parts: (1) the specification of the program presented in the display, (2) the program itself, and (3) the specifications of programs invoked by this program. The displays are intended to be used by software engineers as a reference document during inspection and maintenance. This paper also introduces a specification technique that is a refinement of H.D. Mills's (1975) functional approach to program documentation and verification; programs are specified and described in tabular form.<>