The hub between person, machine and interaction comprises hard- and software parts. A differentiation between staging space and imaginative space similar to that made by Wulf R. Halbach is necessary in order to to describe the criteria for interfaces more accurately.
As the first level of the interface the staging space includes all the elements that contribute to the production of an interface metaphor. In this case these include hardware such as the keyboard, monitor and mouse and the user interface in terms of software. Thus the staging space are the tractable user surroundings. The transitional objects linking staging space and imaginative space are also included here.