[LEAPSECS] final report of the UK leap seconds dialog

[Brooks Harris]

On 2015-02-05 05:53 PM, Kevin Birth wrote:
> If one can read Japanese (which I can do with great difficulty and veeerrrry slowly), one notes that the official Japanese announcement refers to the IERS and the leap second policy, but it translates UTC 23:59:60 on June 30 into the local time of 8:59:60 on July 1.   So Japan follows the policy, but the policy does result in next leap second occurring on the morning of July 1 locally.

But there's no *specified* standard, I think, right? Warner points out 
it "I believe it follows trivially from the definition of timezones.". 
I'm not so sure it "follows trivially", especially that there's no 
*official* specification for "time zones" either, as far I can tell. The 
"offset from UTC" is referenced in ISO 8601 but only provides for 
representing that offset, not defining its meaning.

The “International Meridian Conference” (more properly, the "The 
International Conference Held at Washington for the Purpose of Fixing a 
Prime Meridian and a Universal Day. October, 1884") did NOT adopt the 
resolution to establish a “date line” or “time zones”. The following 
proposal was defeated:

"The Conference recommends as initial point for the universal hour and 
the cosmic day the mean mid-day of Greenwich, coinciding with the moment 
of midnight or the beginning of the civil day at the meridian 12 hours 
or 180 degrees from Greenwich. The universal hours are to be counted 
from 0 up to 24 hours."

That proposal was “lost”, in the words used at that conference, and no 
official proclamation of these facts has since been proposed or 
approved. Nonetheless, the idea of “beginning of the civil day at the 
meridian 12 hours or 180° from Greenwich” has found its way to common 
use, but also (unofficially) extended to +13:00 and +14:00.

Many aspects of "local time" or "civil time" are left to "common 
practice" which is not good enough to expect uniform inter-operable 
implementations. We here concentrate on discussions of UTC and Leap 
Seconds, which is foundational, yet obviously "local time" is required 
and there's nearly a complete lack of standards that govern it. Fixing 
Leap Seconds, either by more clearly defining it so implementations can 
get it right (my very strong preference) or ceasing Leap Seconds (which 
some hope will mitigate the problems but I believe will make it worse) 
doesn't address the elephant in the room - local time.

-Brooks

>
> Cheers,
>
> Kevin
>
>
> ________________________________________
> From: LEAPSECS [leapsecs-bounces at leapsecond.com] on behalf of Warner Losh [imp at bsdimp.com]
> Sent: Thursday, February 05, 2015 5:36 PM
> To: stephenscott at videotron.ca; Leap Second Discussion List
> Subject: Re: [LEAPSECS] final report of the UK leap seconds dialog
>
> The leap second happens world wide in UTC at 23:59:60. Since all time zones follow UTC,
> it is whatever time that is offset from UTC. Otherwise, the offset would no longer be fixed,
> but variable for a few hours. While there isn’t a standard for this, I believe it follows trivially
> from the definition of timezones.
>
> I’ve never seen any jurisdiction that’s done it differently ever. That’s just the sort of thing that
> people would bring up arguing against leap seconds because it would be insanely stupid to
> do this.
>
> I’m also pretty sure that a local time zone isn’t a local time scale in the strictest sense of
> time scale. Again, I don’t have a reference to site for this.
>
> Warner
>
>> On Feb 5, 2015, at 2:37 PM, Stephen Scott <stephenscott at videotron.ca> wrote:
>>
>> Hello Kevin.
>>
>> The information specifying that for Japan the next Leap Second will be applied Wednesday, July 1, at 9:00. is interesting in that this is the first official policy on when the Leap second shall be applied to a local timescale. Maybe I have been looking in teh wrong places.
>> This is a local decision for a local time.
>>   I am not aware of any international standards that touch the subject.
>> I would be interested in learning about other jurisdictions that may have published a policy.
>>
>> Stephen Scott
>>
>> On 2015-02-05 09:35, Kevin Birth wrote:
>>> Wednesday, July 1, at 9:00.
>>
>>
>>
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>>
>>
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