lusters, notification objects are not actual instances of the NSNotification class but of one of its private subclasses. Although a notification object's class is private, its interface is public, as declared by the abstract superclass, NSNotification. (See &quot;Class Clusters&quot; in the introduction to the Foundation Kit for more information on class clusters and creating subclasses within a cluster.)</font>

<p><font face="Times">You instantiate a notification object directly by sending the <b>notifica