[tz] Ulyanovsk, Altai Krai and Altai republic on their way to change time zones

[Paul Eggert]

On 02/22/2016 09:07 AM, Matt Johnson wrote:
> it looks like both of the new zones also have differing history (other 
> than LMT) from the zones they were split from.  Was this intentional?

Yes, the pre-1991 data come from Shanks & Pottenger, which is cited 
earlier in the 'europe' file as being the default source for old data. 
Shanks is not a good source but is the best we have for old data, and it 
says the new zones differ before 1970. My guess is that Shanks tried to 
find the dates for when these locations changed hands during the Russian 
Civil War, and used them to guess time transitions. Quite a bit of 
guesswork there, but it's the best we've got.

> Asia/Barnaul should be the same as Asia/Omsk before 2016, but looks 
> like they also deviate considerably before that.  Looks like rule 
> Russia is on the wrong lines, Omsk has an extra 2011 entry that 
> Barnaul doesn't, and the offsets differ as well.

Thanks for checking that. I attempted to glue together the Shanks data 
with our post-1991 information. We have gaps in our information about 
the 1990s, so I guessed the gaps. Now that you mention it, my guess was 
probably not the best, as it should have prioritized our post-2000 data 
(which is more reliable) over our pre-2000 data. Also, I should 
definitely document that it's a guess, just like our guess about Tomsk 
in 1993. Further proposed patch attached (I've installed this in the 
experimental github version).
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-Improve-Barnaul-guesswork.patch
Type: application/x-patch
Size: 2290 bytes
Desc: not available
URL: <http://mm.icann.org/pipermail/tz/attachments/20160222/56b83c0e/attachment.bin>