Defining Controller Relations
Context
Controllers are built in a hierarchy. View controller should only hold data that concern the view itself. Data that are to be used in more than one view or hold data from the back-end, belong to the component controller or to a custom controller.
To get access to this data in the view, you have to map the context of the respective view controller to the component or custom controller context. The data is hold in the custom controller and you reference to this context in your view context.
Mapping contexts is done by drawing data links from one controller to another and specify the context nodes, you want to map. You always map from a controller that is ranking below in the hierarchy.