C++ Programming Question:

A node class is a class that,
► relies on the base class for services and implementation,
► provides a wider interface to the users than its base class,
► relies primarily on virtual functions in its public interface
► depends on all its direct and indirect base class
► can be understood only in the context of the base class
► can be used as base for further derivation
► can be used to create objects.
A node class is a class that has added new services or functionality beyond the services inherited from its base class.