A subapplication is an application that is part of another application. You use it to organize the class definitions and extensions of an application.

A subapplication is a reusable component. It can contain other subapplications. It can be part of several applications. When you load a subapplication, however, the subapplication can be loaded into only one application at a time in your image. Thus, two separate applications cannot simultaneously load the same subapplication in an image.

Subapplications are used for two main reasons. The first is to organize classes into functional units, either for ease of reuse or maintainability. The second is to define platform lineups. Thus, an application could load different subapplications, depending on which platform the image is located.

Subapplications do not maintain a list of prerequisites. The prerequisite applications are maintained by the root application.