PS. I was a bit too quick with my email; that is not to say that I don't suspect there to be a problem. It appears to depend on whether the left-hand side of the matches clause is a field or a Java expression. For instance: f : Fact( w matches "\." ) does not require escaping in accordance with the documentation, but if I match on a different expression: f : Fact(w.somebeanproperty matches "\\.") escaping the "\" becomes required. - Godmar On 9/25/07, Godmar Back <godmar(a)gmail.com&gt; wrote: > The documentation states that '\' occurring in matches clauses do not > need escaping. However, unescaped '\' cause this error message when > compiling the .drl file: > > Exception in thread "main" org.drools.rule.InvalidRulePackage: Unable > to determine the used declarations : [Rule name=Apply XML Descriptor, > agendaGroup=MAIN, salience=0, no-loop=false] > > at org.drools.rule.Package.checkValidity(Package.java:419) > at org.drools.common.AbstractRuleBase.addPackage( AbstractRuleBase.java:292) > > Escaping the '\' as is customary in Java makes the code work. > > - Godmar > _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users