The code in a CSL module specifies a return value by using rules. Each rule, upon evaluation, either succeeds or fails. If a rule fails, rule evaluation terminates and the value false is returned. When all the rules in a module succeed, the value true is returned. The returned value is used to help determine process and operation routing—see Working with Cost Model Logic for more information on how return values help determine routing.

Only the following types of CSL modules return a value: