The subclassTransientAllowed class option enables you to set the transientAllowed and subclassTransientAllowed class option values for all subclasses of this class.
When the subclassTransientAllowed option is set to false on a superclass by unchecking the Allow Transient Subclass Instances check box on the Lifetime sheet of the Define Class dialog, the Allow Transient Instances and Allow Transient Subclass Instances check boxes are disabled on the Lifetime sheet of the Define Class dialog for all subclasses of the current class so that you cannot change these values. (For details, see "Adding Classes to Your Schema", in Chapter 3.)