Cross-Component Context Mapping 

A third way of using the content of the interface controller of a used component is the cross-component context mapping.

As soon as you have declared the usage of the interface controller and instantiated the external component as described in the procedure of the section above, the context of the external interface controller is available for mappings. On the Context tab page of a controller for which a usage of the external interface controller has been declared, you see the context of this interface controller on the right side of the editor and you can define a mapping for a node of your current controller context to a node of the interface controller context.