Source : Free On-Line Dictionary of Computing

TSL-1
     
        Task Sequencing Language.  Language for specifying sequences
        of tasking events in Ada programs.
     
        ["Task Sequencing Language for Specifying Distributed Ada
        Systems", D.C. Luckham et al in PARLE: Parallel Architectures
        and Langs Europe, LNCS 259, Springer 1987, pp.444-463].