The Free On-line Dictionary of Computing (30 December 2018):

Constraint Handling In Prolog

    (CHIP) A constraint logic programming language
   developed by M. Dincbas at ECRC, Munich, Germany in 1985 which
   includes Boolean unification and a symbolic simplex-like
   algorithm.  CHIP introduced the domain-variable model.

   ["The Constraint Logic Programming Language CHIP", M. Dincbas
   et al, Proc 2nd Intl Conf on Fifth Generation Computer Sys,
   Tokyo (Nov 1988), pp.249-264].

   ["Constraint Satisfaction in Logic Programming", Van
   Hentenryck.  Available from COSYTEC, 4 rue Jean Rostand,
   F91893 Orsay, France].

   (1994-11-15)