Forward chaining debugging may be turned on by typing
and off by typing
When KnowledgeWorks is started, debugging is on. Debugging allows the actions of forward chaining rules to be single-stepped like backward chaining rules (see Backward Chaining Debugging), and also records information on which objects are modified by which rules. For information on how to use the debugging tools, refer to The Programming Environment.
KnowledgeWorks and Prolog User Guide (Unix version) - 6 Dec 2011