[tz] Why did you rename Russian zone name abbreviations

[Paul Eggert]

On 11/02/2016 01:58 PM, Alexander Belopolsky wrote:
> There may be exceptions historically, but as a rule Russian timezones 
> are defined as fixed offsets from Moscow, so when Moscow Time changes, 
> so do all the timezones. 

This depends on what one means by "historical". Of course if one goes 
back before 1930 things get weird by modern standards. However, even 
recently, Vladivostok time has not been at a fixed offset from Moscow 
time. For example, in 2014 (the last time Russian clocks changed in a 
big way) Vladivostok changed seven hours earlier than Moscow did. Given 
this typical practice, we cannot simply use "MSK+07" as the abbreviation 
for Vladivostok time, as this abbreviation would be incorrect for 
several hours whenever Russians change their clocks. Another practical 
objection to "MSK+07" is that it would likely confuse users into setting 
the POSIX TZ environment variable to "MSK+07", which would not work as 
desired as it would use US Mountain Standard Time and call it "MSK".

Although abbreviations like "VLAT" avoid these problems, they run into 
other issues. Because "VLAT" is not a fixed offset from UTC it departs 
from the usual English-language semantics for time zone abbreviations, 
misleading English-language readers. Also, what do we do with locations 
like Europe/Barnaul, which switched from +06 to +07 in March of this 
year? Should Barnaul use the abbreviation "OMST" (Omsk time) before 
March, and "NOVT" (Novosibirsk time) after? Or should it now use "BART" 
for all dates? Neither alternative is satisfactory and neither reflects 
common practice in English. In contrast, using numeric abbreviations is 
simple and requires no arbitrary inventions on our part.