[tz] Today's CalConnect event

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Tue Feb 12 17:21:09 UTC 2019

On 2019-02-12 05:30, John Wilcock wrote:
> Le 11/02/2019 à 17:49, Steve Allen a écrit :
>> For comparison with the IANA tz data, the IATA has a database of time
>> zones as an appendix to a document called SSIM. That consists of
>> records of 390 ASCII characters in columns at a cost of $1329.00 USD
>> https://www.iata.org/publications/store/Documents/Passenger%20Standards/specifications-utc-app-f.pdf
>> SSIM is structured as the offsets currently in effect; history is not
>> included.  It is unclear to me why an airline would subscribe to this
>> information rather than rely on IANA tz.

Info is provided by governments directly to national air operators, and probably
also international air operators into those countries, many of whom will be IATA
This tz db list would like governments to add the tz at iana.org list mailing
address to their time change email distribution lists which include air operators.

> Does IANA have access to this IATA data? Can anything be learnt from a
> regular comparison of offsets?
If someone wanted to donate the purchase of an annual SSIM licence to the
maintainer or IANA, it could be used for reference comparisons.
If an --ssim option were added to zdump to produce the same format, comparisons
could be produced by licensees.
Results could be shared as long as the licensed data were not reproduced
verbatim to conform to the licence e.g. a field level comparison could show the
IANA data for reference, with only the effects of the differing SSIM fields shown.

A field level diff could easily be produced in any convenient scripting
language, by anyone with suitable skills, and access to licensed data for testing.

This would be useful to the major software vendors subscribed to this list, who
should probably be subscribed to SSIM Appendix F data, to have access to
complete and diverse information for verification and validation.

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

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