KnowledgeWorks rules are defined as follows:
<rule> ::=
(defrule <rule-name> {:forward | :backward} <body>)
Every rule must have a unique name which must also be distinct from any KnowledgeWorks object class name and from any context (rule-group) name. The expressions which form the body of a rule have the same syntax and meaning regardless of whether they occur on the left or right hand side of a forward or backward chaining rule.