> The tzdata time zone abbreviations are proleptic.

As a general rule, yes. There are a few attempts to capture the history of time zone names; in the US take, for example, Eastern War Time and Eastern Peace Time (please).

    --ado

On Wed, Oct 19, 2016 at 4:26 PM, Paul Eggert <eggert@cs.ucla.edu> wrote:
On 10/19/2016 03:40 AM, Karel Volný wrote:

the problem is, as far as _other_ people are concerned, they find the classical abbreviations useful


 Not many people object to truly classical abbreviations like GMT and EST; it's our inventions like LKT that are more problematic.

I believe vitually everyone in Russia able to read Latin could understand what YAKT means

 Hmm, well, I just now did a Google search for "YAKT site:ru" and the first match was for a Russian-language description of Yakt, Montana (and I've visited near Yakt and it's beautiful country - but it's not Yakutsk). None of the first ten matches were about Yakutsk time. With more-specialized searches one can find instances of "YAKT" to mean Yakutsk time, largely because of the tzdata invention in earlier releases. But it's more common for English-language sources to call it "Yakutsk time" with no abbreviation; or when abbreviations are used, to say something like "UTC+9" or "MSK+6".

it is very bad that the change was done in a way that it applies even for older timestamps

 The tzdata time zone abbreviations are proleptic. That is, they are the English-language abbreviations we use *now* for old time stamps, and these abbreviations may differ from abbreviations used back then (often because hardly anybody used abbreviations back then). It might be nice to also support contemporaneous abbreviations, or abbreviations based on tzdata release number, but that would be a harder task and I will be happy to let some other project take it on if there is interest.