[rules-users] Is "or" allowed in a rule? Can I link the rules?

I'm a beginner user of Jboss, please bear with my maybe dumb questions: 1. Seems to me that the conditions in a rule are always connected with "AND" relation: such as the following rule if C1 C2 C3 then D1 it means "if C1 and C2 and C3, then D1" Is "or" allowed? I mean , can I express: "if (C1 or C2 or C3) and C4, then D1" in 1 rule? Right now, I can only use 3 rules to express it: if C1 C4 then D1 if C2 C4 then D1 if C3 C4 then D1 2. Can I form a link of rules? Can rule A's decision (the Then part) be rule B's condition (The When part)? for instance: rule A: if C1, C2, C3 then D1 rule B: if D1, C4 then D2 When the complexity increases, the number of rules explodes. I browsed the document and didn't find a clue. I'm using the 4.0.7. Your help is highly appreciated.