Object-oriented programming systems not related to CLOS.

lang/lisp/oop/non_clos/

   cool/      COOL: Implementation of HP's CommonObjects on top 
              of the PCL metaclass kernel.
   corbit/    CORBIT and BOOPS: Object-oriented extension of 
              Common Lisp based on a prototype (classless) 
              model of OOP.
   mcs/       MCS: Meta Class System, a portable 
              object-oriented extension to Common Lisp.

See Also: 

   areas/kr/