On 9/16/21 3:47 AM, Michael H Deckers wrote:
The charter of tzdb is to provide software that represents local times as defined by local authorities.
That is indeed our goal. However, the situation in question has never occurred so there are no local authorities to consult. So we're trying to predict what future local authorities will do (a common problem in tzdb, unfortunately...). My guess is that in the unlikely event that a local authority specifies a non-minute UTC offset, if we go to that authority and say something like this: "We can implement two possibilities: "(A) Your timestamps will be unambiguous, but this will complicate some obscure calculations on old-fashioned platforms during the trailing part of a leap-second minute. "(B) We can simplify those obscure calculations, but your timestamps will be ambiguous." then the local authority will pick (A). I doubt it'll pick (B). Of course I could be wrong. And it's also possible that a local authority would pick something that's neither (A) nor (B), though it's unclear what that would be (apparent solar time, perhaps?). From what we know now, though, I think we're better off implementing (A) than implementing (B). If this unlikely event ever occurs and local authorities choose something other than (A), I hope we can adjust tzdb to what they actually do, much as we already adjust tzdb for other occasions where local authorities make unexpected changes. (If they choose apparent solar time I expect we'll be out of luck though....)