Source : Free On-Line Dictionary of Computing

MCS
     
        Meta Class System.
     
        A portable {object-oriented} extension of {Common Lisp} from
        {GMD}.  It integrates the functionality of {CLOS} and {TELOS}.
     
        {(ftp://gmdzi.gmd.de/pub/lisp/mcs)}.
     
        (1994-10-21)