As the subject heading suggests, the engineering of a rules system is one thing - the modification of such a system is another. Why ?? Most vendors are touting the ability to have multiple business users writing rules, e.g. Tessie the Typist is told to write a modification to the business rules in her free time between midnight and dawn and the CEO decides he can dabble in rules engineering also by augmenting what he told Tessie to do. The result ?? PURE CHAOS !!!!!!!! Putting multiple rules into an environment and letting them "fight it out" is suicidal !! Any logic in a rules system must be well thought out and organized. This is why companies are paying up $300 per hour for "vendor consultants" - to fix this crap. They are smiling "all the way to the bank". Rich Halsey Pensacola, FL USA "may you have fair seas, and a following wind"