A question about Standard assets(Mobile)!

I study the standard assets(mobile) now.I have a question about CameraRelativeSetup scene!I saw the hierarchy of the scene have CameraPivot and CameraOffset.How to make them?I know Dual Joysticks is a prefab and Camera Relative Controls is another.But what are CameraPivot and CameraOffset ?They dont like gameobject ,too.And I saw CameraPivot have script and transform property which CameraRelativeControl script use it as variable!CameraOffset only have transform property like prefab.I really cannt understand about them!I want to make a likely scene,how to make hierarchy like this.Please help me!Thanks!