Source : Free On-Line Dictionary of Computing

SDL
     
        Specification and Design Language.
     
        Defined by the {ITU-T} (recommendation Z100) to provide a tool
        for unambiguous specification and description of the behaviour
        of telecommunications systems.  The area of application also
        includes process control and real-time applications.  SDL
        provides a Graphic Representation (SDL/GR) and a textual
        Phrase Representation (SDL/PR), which are equivalent
        representations of the same semantics.  A system is specified
        as a set of interconnected {abstract machine}s which are
        extensions of the {Finite State Machine} (FSM).
     
        1. System Software Development Language.  System software for
        the B1700.  "System Software Development Language Reference
        Manual", 1081346, Burroughs Corp (Dec 1974).
     
        2. Specification and Description Language.  {ITU-T}.
        Specification language with both graphical and character-based
        syntaxes for defining interacting extended finite state
        machines.  Used to specify discrete interactive systems such
        as industrial process control, traffic control, and
        telecommunication systems.  Proc Plenary Assembly, Melbourne
        14-1988-11-25, Fasc X.1, CCITT.  "Telecommunications Systems
        Engineering Using SDL", R. Saracco et al, N-H 1989.  Available
        from Verilog, MD.  (See XDL).
     
        3. Shared Dataspace Language.  "A Shared Dataspace Language
        Supporting Large-Scale Concurrency", G. Roman et al, Proc 8th
        Intl Conf Distrib Comp Sys, IEEE 1988, pp.265-272.
     
        4. Structure Definition Language.  Used internally by DEC to
        define and generate the symbols used for VAX/VMS internal data
        structures in various languages.
     
        5. System Description Language.  language used by the Eiffel/S
        implementation of Eiffel to assemble clusters into a system.
        (see Lace).