7.2.3.0.1 Required Modules.

The modules which are necessary for a proper operation of a module and, therefore, need to be loaded before bootstrapping of this module, are listed in the :needs method of the new module's definition. These modules will be loaded unless they have already been loaded before. It should be stressed that each (sub)-module not only stands for itself, but also for all modules that are needed by that (sub-)module.