[tz] Recommendations to governments about time zone update notice period and format

Brian Inglis Brian.Inglis at Shaw.ca
Wed Mar 8 15:27:17 UTC 2023

On 2023-03-08 00:55, Paul Eggert via tz wrote:
> On 2023-03-06 03:41, Neil Fuller via tz wrote:
>> [*] e.g. maybe something like "Many downstream users of the TZDB wait ...
> Thanks for the suggested wording. I folded it into a new section in 
> tz-link.html, with the title "Coordinating with governments and distributors", 
> by installing the attached proposed patch. Once it's released (which should be 
> soon, for Egypt) we can cite this URL:
> https://data.iana.org/time-zones/tz-link.html#coordinating
> Further comments welcome of course.

+Many downstream timezone data distributors wait for
+a <code><abbr>tzdb</abbr></code> release before they produce an update

Prefix "official" before "release" and suffix something like "announced on the 
official tz-announce mailing list, see:
for details, to subscribe, or view the archives:

Are no current or latest month archive links supported as on some lists?

> Brian suggested something more ambitious (and more laborious...).

They have the greater needs, presuambly documented and scheduled processes, and 
the funding to coordinate more comprehensive and expansive documents, explaining 
their needs, processes, and time frames.

> I sometimes wonder how the IATA's process works for updating the SSIM's time 
> zone appendix. Since they charge $1000/year for the SSIM I've never used it 
> directly.

Can't even read the procedure without paying the fee!
For background see:
"IATA schedules conferences
Schedules Conferences are held twice each year (June and November) about five 
months before the start of the respective schedules seasons and are organised by 
Slot handback deadline
Unwanted slots must be returned no later than January 15 for the next Northern 
Summer season and no later than August 15 for the next Northern Winter season."


There are also notice periods like notification of cancellation three weeks 
prior to operation of a scheduled slot.

Presumably on a short notice time change, the slots in UTC are bumped in local 
time, to avoid disrupting schedules, and it is presumably then up to commercial 
airlines to apply for exemptions and make provisions for Justified Non-Use of 
Slots (“JNUS”) if they lack demand, ATC, airline, or airport personnel to 
operate commercial scheduled flights at those slot times, or negotiate with 
other carriers/operators for slot exchanges.
Of course there may be national, airport, or airline regulations that mandate 
operation for political reasons or to maintain slots (e.g. EU 80%).
Those with experience of IATA schedules, airline/airport operation, or travel 
industry can correct any presumptions.

Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry

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