TAI zone?

Paul Koning paul_koning at Dell.com
Wed Jun 29 18:27:53 UTC 2011

"Remove leap seconds from UTC" is clearly absurd, and I'm baffled that ACM would lend its good name to such a notion.  UTC is defined as atomic time plus leap seconds, for good and sufficient reasons.  And as was pointed out, TAI already exists for those who want atomic time plain, without leap seconds.

The quoted Linux description is even more bizarre, since "TIA .. includes leap seconds" is a complicated and misleading way of saying "UTC".

I wonder if this requests amounts to "Posix should be extended to provide an interface to TAI".  If so, that certainly makes sense.  Is that something tzdata can do, or does it have to be done in some other layer?


On Jun 29, 2011, at 1:16 PM, Olson, Arthur David (NIH/NCI) [E] wrote:

> I'm forwarding this message from David Magda, who is not on the time zone mailing list; those of you who are on the list, please direct replies appropriately.
>    --ado
> ________________________________________
> From: David Magda [dmagda at ee.ryerson.ca]
> Sent: Wednesday, June 29, 2011 11:26 AM
> To: tz at lecserver.nci.nih.gov
> Subject: TAI zone?
> [Not a subscriber, so please CC.]
> Hello,
> There's been some discussion of removing leap seconds from UTC, as some
> people need/want a more predictable and deterministic time scale. [1]
> Given that International Atomic Time [2] exists, there doesn't seem to be
> an easy way to reference it.
> Is there any reason why a TAI "time zone" ("TZ=TAI; export TZ") is not
> present for those that want to ignore leap seconds? I noticed that some
> Linux distributions have a "right/" directory [3] to deal with this in
> some way:
>> Two different versions are provided:
>> - The "posix" version is based on the Coordinated Universal Time (UTC).
>> - The "right" version is based on the International Atomic Time (TAI),
>>  and it includes the leap seconds. [...]
>> - TZDIR=/usr/share/zoneinfo/posix TZ=Europe/Paris on a system with
>>  hardware clock set to UTC.
>> - TZDIR=/usr/share/zoneinfo/right TZ=Europe/Paris on a system with
>>  hardware clock set to TAI.
> Regards,
> David
> [1] http://cacm.acm.org/magazines/2011/5/107699-the-one-second-war/fulltext
> [2] http://en.wikipedia.org/wiki/International_Atomic_Time
> [3] /usr/share/doc/tzdata/README.Debian

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