[LEAPSECS] Windows Server 2019

Stephen Scott stephenscott at videotron.ca
Mon Jul 23 13:58:49 EDT 2018


What I was trying to get an answer to is "Why is the one leap second 
treated any different from the other 86400 seconds in the day when 
offsetting the UTC time to a UTC offset time zone?"

Yes, ITU-R TF 460-6 defines the timing of the leap second in UTC.

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.


On 2018-07-23 11:40, Steve Allen 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.
> --
> Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
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