MASCOT is a software engineering methodology developed under the auspices of the United Kingdom Ministry of Defence starting in the early 1970s at the Royal Radar Establishment and continuing its evolution over the next twenty years. The co-originators of MASCOT were Hugo Simpson [Ref. 1] and Ken Jackson (currently with Telelogic UK Ltd).
Its primary purpose (unlike most software design methodologies) is to bring rigour and structure to the architectural aspects of software development [Ref. 2]. Its creators purposely avoided saying anything about the functionality of the software being developed, and concentrated on the real-time control and interface definitions between concurrently running processes.
MASCOT was successfully used in a number of defence systems, most notably the Rapier ground-to-air missile of the British Army. Although still in use on systems in the field, it never reached critical success and has been subsequently overshadowed by Object Oriented design methodologies such as UML.
A British Standard Institute (BSI) standard was drafted for version 3 of the methodology [Ref. 3] but was never ratified. Copies of the draft standard can be still obtained from the BSI.
References: 1. http://www.cs.ncl.ac.uk/people/home.php?id=159 2. Simpson, H. 1986. The Mascot method. Softw. Eng. J. 1, 3 (May. 1986), 103-120. ISSN:0268-6961 3. DD 196:1991; Guide for a modular approach to software construction, operation and test (MASCOT)