Actually thinking about it, there is a neat way of encoding hour 2A in a distinguishable way even on "analog" clock displays: Just stop the motion of the hour pointer for 60 min during hour 2A, and it will be immediately recognizable whether you are in hour 2A or 2B (except perhaps for the first few minutes of the hour, where the smaller pointer hasn't moved yet much during hour 2B).

Well, for clocks I do not think it matters as much as that. Since the days that DST was introduced in the Netherlands (the 70s), in Amsterdam the switch over of public clocks was done by letting them run at half speed or at double speed during an hour. As far as I know nobody did complain (but perhaps nobody is using those clocks as they are always a few minutes slow compared to the clock the Dutch railways uses?) I seriously doubt the "second exact" time some people say they need on their watches. But who am I, I do not have a watch. dik -- dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland, +31205924131 home: bovenover 215, 1025 jn amsterdam, nederland; http://www.cwi.nl/~dik/