Zefram schreef: > My intention was that you'd be able to name a GAT+offset zone if useful. > The offset syntax is for occasions when an unnamed zone is temporarily > required.
Perhaps Riyadh would be a GAT based time zone, and perhaps in Victorian times, there was a regulated system of time zones in Britain, but I would expect a GAT based time scale to be valid at one point only (well ok, on a meridian to be exact), and GAT+offset to be the most common way of specifying it. > >+01:00 - offset; interpreted as timezone relative to UTC (always) > > I'd like to deprecate the bare offset. I think the base should be > explicitly specified. Perhaps you'd like to do that, but this is the most common way of specifying time zones in practice (unfortunately). Best thing would be to just say "if a time scale is not specified, it's UTC. > >Europe/London - Olson time zon; possibly using DST; relative to UTC > > I want to be able to name zones that are not based on UTC. Certainly want > to have timezone data that predates the existence of UTC. The choice > of base timescale is a feature of the zone, not fundamental to the > timezone system. Currently, as I said, none of the Olson time zones (which are the time zones used in practice, not the legal time scales) are based on anything but UTC. As far as I can imagine. Historical data; well that's a problem. > >UTC+01:00, UT1+01:00 - offset+time scale > > Yes. > > >UTC-Europe/London, UT1-Europe/London ??? - Doesn't look too bad? > > If this feature is to be supported, I'd prefer to make it explicit that > you're taking the offset part of the named zone and ignoring its built-in > base time scale. Also better to use "+" than "-" here, lest it appear > that you want to apply the opposite of the UK time offsets. It's not a minus sign, it's a hyphen. But perhaps '+' is better. > Of these eight distinct classes, I think we only want the database for > the first class of name (pure geographical). If we're extending the > timezone namespace then we can decide for ourselves what to do for > backward compatibility. Conveniently, the pure geographical names > follow a fairly restrictive syntax: no digits, no "+", no "-" in the > first component. And all of them are in about 9 geographical categories (Europe, America, etc.) I'd say that is enough to recognize Olson time zones; and to disambiguate slashes: Europe/Something is an as-yet unknown Olson time zone; Something/SomethingElse is a time scale. > >User interface could be better, > > Which aspect of it? User friendliness was certainly not a major > consideration in writing it, but I'm open to suggestions. I don't like the way you have to specify the format on the command line. It really asks for something Template-like. But I don't have any concrete suggestions. > I certainly do plan to do the astronomical time scales. <snip interesting and exciting plans> Sounds good! Eugene
