In my paper two vital distinctions are made; the distinction between shopping on the one hand and paying on the other the distinction between home access and public access systems. Following this the paper can be divided in four parts. The paper has become a state of the art document in the sense that I have tried to locate all main developments on the subject in the Netherlands. While finishing this paper some research projects have only just started or have not yet been completed. As appropriate, new results will be included in the presentation in September 1987.