On 2019-07-24 08:45, Alois Treindl wrote:

In my humble opinion, I think the choice TZ made for India, by selecting Kolkata
(formerly Calcutta) as the reference
location, was not a good choice.

   I can understand your point -- but it is definitely
   not applicable to tzdb data which is not meant to
   cover historical data:

      However, the database is not designed for and does not suffice for
      applications requiring accurate handling of all past times everywhere,
      as it would take far too much effort and guesswork to record all
      details of pre-1970 civil timekeeping. (from theory.html)

   On the contrary, the tzdb rules for selecting a representative
   location for a time zone are carefully constructed so as
   to avoid political or other extraneous implications as far
   as possible. Past experience shows that this is a very
   advantageous design.

I am fully aware of that.

BUT: For the chosen city to represent a zone from the 1970 data, all past history must also be presented correctly.
This is difficult given the uncertainty of time in Kolkata up to 1941.

TZ was conscious of that problem and chose the artificial 'railway time' which seems clearly NOT the time used in Kolkata on the ground for all civil purposes. See comment in the TZ source.

The rule "Use the most populous among locations in a region" has also been broken with the choice of Kolkata.