[LEAPSECS] Windows Server 2019

[Warner Losh]

On Mon, Jul 23, 2018 at 9:40 AM, Steve Allen <sla at ucolick.org> wrote:

> On Fri 2018-07-20T12:16:07-0600 Warner Losh hath writ:
> > Unless you are at UTC+0, I don't see how this can be right... Leap
> seconds
> > happen during the day for most time zones...
>
> On Fri 2018-07-20T16:11:12-0400 Stephen Scott hath writ:
> > What I am asking is WHY.
> > Where is the standard for that?
> > Or at least some document that specifies that?
>
> On Mon 2018-07-23T14:05:13+0100 Tony Finch hath writ:
> > The standard for leap seconds is ITU-R TF.460
> >
> > https://www.itu.int/rec/R-REC-TF.460/en
>
> Most legislation and decrees about legal time specifies that the local
> civil time is some number of hours and minutes different from GMT or
> UTC.  Taking the simplest interpretation on January 1
> on every other day      23:59:59 UTC is 15:59:59 PST
> on every other day      00:00:00 UTC is 16:00:00 PST
> so most simply          23:59:60 UTC is 15:59:60 PST
> If the base time in the law or decree is GMT (as it was in the US
> until 2007) then all of this is by convention following whatever
> official metrology agency is tasked with providing legal time for that
> jurisdiction.
>
> A law could specify what Microsoft reportedly did in Azure, that is,
> Kiribati could apply the leap at the begin of their January 1 13 hours
> before of 0h UTC, and Hawaii could apply the leap 11 hours after 0h
> UTC, but it is hard to imagine legislators and bureaucrats getting
> that specific unless their metrology agencies provided powerful
> technical arguments about why being off by one second for all of those
> hours was less harmful than taking the leap second in the middle of
> the day.  That might happen if some international regulatory or
> scientific agency produced a recommendation saying that every nation
> should do leap seconds at local midnight, but that just moves the
> "hard to imagine" into a different arena.
>

When this has come up in the past, no examples of that were offered.
There's some niggles for a couple places that still use "local solar time"
(whatever that means, since it specifically isn't UT1 or a mean solar
time), but those places don't use leap seconds. No examples have been
brought forward, and I'm with Steve on this: Local bureaucrats likely don't
care enough to specify that detail, and most certainly wouldn't stick their
neck out to be the odd-man-out in this arena.

I do know it is certainly the case that in the US, EU, China, Japan, NZ and
AU that local authorities construe their laws to mean the leap second
happens at midnight UTC, but I have have no specific documentation or
regulations I can point to for that. Just the conversations with Judah
Levine I had years ago when they were looking at getting rid of leap
seconds because they were troublesome in Asia where they happened in the
middle of the day... I believe the issue was documented in many of the
"Turin" meeting docs.

Warner
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