
 Defines a new CLOS class as  defclass does. However, if none of the given superclasses is a subclass of  named-kb-object , then  named-kb-object is added to the list of superclasses. The class inherits a name slot kb-name of which the initialisation form ( :initform ) generates a symbol from the class name using  gentemp (See  Common Lisp: the Language  (2nd Edition)).
(def-named-kb-class vehicle ()
((driver :initarg :driver)))
(def-named-kb-class truck (vehicle)
((load :accessor truck-load)))