[tz] Dropping coordinates from zone1970.tab?

Paul Eggert eggert at cs.ucla.edu
Wed Sep 29 21:50:24 UTC 2021

On 9/29/21 14:26, Aurelien Jarno via tz wrote:
> If you consider a world map to select the timezone, with each timezone
> represented by a circle from the coordinates in the zone1970.tab

zone1970.tab has never been intended as a "nice" geographical interface 
in that sense. At the end of this email is a tzselect sample session 
(using 2021a, so more-recent changes are irrelevant) that uses 
nearest-neighbor from the South Pole, employing zone1970.tab's data. As 
you can see, tzselect prompts with ten nearest neighbors that are all 
incorrect because the correct answer is Pacific/Auckland, which is 
nearly 6,000 km away.

Akthough I'm sure this way of using tzselect could be improved a bit, 
it's hardly worth the trouble as almost nobody uses it this way (the few 
people who use tzselect, typically don't take choice "10)" below). 
Instead of tzselect, most people use maps based on data that are 
proprietary (or cited in tz-link.html) and are outside tzdb's scope. 
These maps commonly depict some tall skinny timezones one of which could 
easily incorporate both Auckland and the South Pole (such a timezone 
need not be visually contiguous), and this is what I suggest for 
user-facing interfaces based on distances. Riyadh and Syowa can be 
handled similarly.


$ tzselect
Please identify a location so that time zone rules can be set correctly.
Please select a continent, ocean, "coord", or "TZ".
  1) Africa
  2) Americas
  3) Antarctica
  4) Asia
  5) Atlantic Ocean
  6) Australia
  7) Europe
  8) Indian Ocean
  9) Pacific Ocean
10) coord - I want to use geographical coordinates.
11) TZ - I want to specify the timezone using the Posix TZ format.
#? 10
Please enter coordinates in ISO 6709 notation.
For example, +4042-07403 stands for
40 degrees 42 minutes north, 74 degrees 3 minutes west.
Please select one of the following timezones, echo listed roughly in 
increasing order of distance from -9000+00000.
1) Antarctica - Vostok		        6) Antarctica - Rothera
2) Antarctica - Troll		        7) Antarctica - Dumont-d'Urville
3) Antarctica - Syowa		        8) Antarctica - Casey
4) Antarctica - Davis		        9) Antarctica - Palmer
5) Antarctica - Mawson		       10) Argentina - Tierra del Fuego (TF)

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