Abstract: The system described herein provides for the reusability of customizations to a software product. Once customizations are made to a software product, using the system described herein, if the software product is revised, the customizations made to the software product can be reused with little or no effort. The system described herein also facilitates the process of customizing the software product. In addition, the system described herein allows customizations made to one portion of the software product to be used by other portions of the software product. The system described herein performs its functionality by utilizing various object-oriented techniques. Object-oriented software products typically comprise a hierarchy of classes. For each class within the software product, the system described herein provides a corresponding empty class that is customizable. As such, the system described herein provides a class hierarchy for a software product that is divided into pairs of classes.