As explained in “Server Objects”, a server object must derive directly or transitively from one of the classes IlsObject or IlsEntity. Potentially, any server object is an object to which a view can subscribe. Such an object, also called a viewed object, must be an instance of the class IlsViewed (or of a subclass).

Since IlsViewed is the base class for the classes IlsObject and IlsEntity, a view can subscribe to any instance of a type derived directly or transitively from these classes.

Moreover, for a view to be able to subscribe to a server object, this object must have been declared to the server model interpreter. This idea is explained in Defining Runtime Access to the Server Model. (See also Notification States.)