Expert system engine. The home page for CLIPS is http://www.ghg.net/clips/CLIPS.html .
See TclCLIPS for a Tcl binding. For an IDE built on TclCLIPS see TixClips.
AM Here is a book that discusses using CLIPS at some length:
Peter Jackson, Introduction to expert systems Addison-Wesley, 3rd edition, 1999, ISBN 0-201-87686-8
See also Playing CLIPS.