On Mon, Jul 23, 2018 at 12:52 PM, Steve Allen <[email protected]> wrote:
> On Mon 2018-07-23T13:58:49-0400 Stephen Scott hath writ: > > I have not found any specifications or official documents that specify > that > > the leap second shall be incorporated just before the time instant > midnight > > UTC for all UTC offset timescales. > > There is no authority for "all UTC offset timescales." > All local times are decided by local jurisdictions. > This is an issue long treated in the IANA tz mail list which > is a community effort that makes best effort to track every > little change made by every legislature and bureaucrat. This is more an absence of a thing. There's plenty of laws that say it's a fixed offset from UTC or some other approximation of Mean Solar Time which everybody construes to mean UTC these days (even if a pedantic reading doesn't lean one here). In the absence of setting a local time for the leap second, the offset is controlling and therefore it happens at UTC midnight, since it's definitely and unambiguously defined in ITU-R TF 460-6 as such (all known earlier revisions too, I believe was the conclusion when a similar issue was raised years ago on this list, though I think -3 was the oldest that could be found at that time). Warner
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