Not that many years ago I worked at a company that had implemented a rules engine for documenting the health and safety information associated with their products, based on rules operating on the chemical formula of the product, with CLIPS [1]. The rules were dynamic. You define the rules and program it in a LISP-like language. It was embedded in a C++ program that generated and fed the rules to CLIPS.

http://clipsrules.sourceforge.net/