--- On Wed, 9/23/09, Chris Richmond <crichmond(a)referentia.com&gt; wrote: Basically, yes. The update statement should be used to indicate that an object has changed. Using it for other purposes is of course possible, but I'd avoid it unless there was good reason. See the attached sample project. Is this what you're doing? I put in a rule that checks the value of an object that is modified externally: rule "Conditional Match" when c : Cycle() d : Data( value < 5 ) then System.out.println( "Conditional Match: " + c + " with " + d ); end Works fine.