SDL--CCITT Specification and Description Language

The CCITT Specification and Description Language (SDL) became a CCITT recommendation in 1976, and a refined version was published by CCITT in 1980. This paper presents the background and history of SDL, and its relation to the other languages recommended by CCITT. SDL is mainly a language to specify and describe the logic of functional processes in a fashion independent of implementation techniques, and is based on a finite-state machine approach. The concepts and representation forms of SDL are briefly explained. A survey is given of today´s applications and tools, and the expected future developments are discussed.