Dear Carsten, Thanks for your comments in the DVI file, which I shall have to study. I downloaded and twice attempted to print (as an A5 booklet) your MFPS article and the other one attached to your web page, but something went wrong with the printing. I'll try again. It would be worthwhile looking at the Lambek & Rattray papers that I cite, as I think they may already have covered a lot of the abstract ground that you're now interested in. "Generalised abstract nonsense" has a tendency to have been done before - I got hit by this myself some time ago when I was generalising stable domain theory. This is the reason why I now write things more concretely ("the RIGHT level of abstraction, as Mac Lane one said) and connect them with the mathematical and computing applications that I know. I would like to come to Birmingham sometime soon to talk to you about these things, and also to Martin about constructing the reals in ASD. Best wishes, Paul