I've put another (revised and expanded) instalment of my reading notes on Logical Options on-line here. Last week's and this week's seminars are on Section 3.1 on "Postulate systems", i.e. axiomatic theories. Again the notes have been dashed off pretty quickly, though helped by stealing a page or two from my Gödel book. Still, they might be useful to some students e.g. meeting the ideas of "models" and "categoricity" for the first time.