Source : Free On-Line Dictionary of Computing

Syntax/Semantic Language
     
        (S/SL) A specification language for {recursive descent
        parser}s by Rick C. Holt and Jim Cordy .
        Rayan Zachariassen  produced the {C}
        implementation.
     
        Unlike most other languages, practicially the LEAST expensive
        thing you can do in S/SL is recurse.  A small language that
        defines input, output, and error token names (& values),
        semantic operations (which are really escapes to a programming
        language but allow good abstraction in the pseudo-code) and a
        pseudo-code program that defines a {grammar} by the {token}
        stream the program accepts.  {Alternation}, {control flow} and
        1-symbol {lookahead} constructs are part of the language.
     
        An S/SL implementation compiles this S/SL pseudo-code into a
        table ({byte-codes}) that is interpreted by the S/SL
        table-walker ({interpreter}).  The pseudo-code language
        probably has an {LR1 grammar} and the semantic mechanisms
        probably turn it into an {LRn grammar} relatively easily.  It
        is more powerful and cleaner than yacc but slower.
     
        {(ftp://ftp.cs.toronto.edu/pub/ssl.tar.Z)}.
     
        ["Specification of S/SL: Syntax/Semantic Language", Cordy,
        J.R. and Holt, R.C., Computer Systems Research Institute,
        University of Toronto, 1980].
     
        ["An Introduction to S/SL: Syntax/Semantic Language" by
        R.C. Holt, J.R.  Cordy, and D.B. Wortman, in ACM Transactions
        on Programming Languages and Systems (TOPLAS), Vol 4, No.  2,
        April 1982, Pages 149-178].
     
        (1989-09-25)