An instance of a class that implements this interface is passed in as a parameter of the [!:Autodesk::Revit::DB::CustomExporter] constructor. The interface methods are then called at times of drawing entities that are currently visible in the view being exported.

With this type of export context used to perform a custom export, Revit will traverse the model and output the model's geometry as if in the process of regular displaying or exporting a 3D View. It means that any geometry which is visible in an open view (taking any current visibility setting applicable to the view) will be processed and output.