Trends in private viewdata systems Available to Purchase

I would like to thank the organiser of the Seminar for giving me such a wide brief: trends in private viewdata systems in the context of where we are now and where we want to go. I shall treat it as a licence to discuss practically anything which has to do with private viewdata systems. I will start with a ‘historical’ section, so as to indicate what qualifications I've got for discussing this subject. Then I'll show what viewdata looks like to me at the moment. Last, I will say where I think viewdata ought to go, or might go, in the future.