Returns an association list of the variables and their bindings in the instantiation . The variables are those produced by the condition part of the forward chaining rule.
For an instantiation of a rule with the precondition
(object ? color ?color-value size ?size)
(inst-bindings inst)
((?color-value . :red) (?size . 20))
KnowledgeWorks and Prolog User Guide (Unix version) - 6 Dec 2011