[tz] Moving more zones to 'backzone'

[Peter Krefting]

Paul Eggert via tz:

>> just realize that it has the same zone1970.tab file as regular tz, so that 
>> will not help at all
>
> Yes, that's right. The only difference between global-tz and default TZDB is 
> that the former has some Zones that differ only in pre-1970 timestamps.

Indeed. It solves the problem I do not have, without solving the 
problem I do have.

>> (I am writing for an embedded system where we cut off old data from before 
>> build time, as it does not preserve information across reboots in anything 
>> but fully written-out text form).
>
> In that case, even zone1970.tab is overkill for your application, which 
> doesn't care about zones that differ only for timestamps in the past.

The zone1970.tab files provides me with a list of time zones, one per 
country, which can be presented to the person to select the time zone. 
Having one unique current time zone per country (and more for the few 
countries that have more than one current time zone) makes it easy to 
find a zone to select

With the zone1970.tab change in 2022b, it is not immediately obvious 
that for Norway, I should select "Berlin" (although I have added the 
commentary, so it does say "Scandinavia").

Our customers in Iceland will probably have a harder time as there is 
no commentary in zone1970.tab (besides the country code) that says 
Iceland, plus that it has placed Iceland in Africa (which is a bit 
weird). Of course, they could just select "UTC" and be done with it, 
which is probably what they do, anyway.

For my purposes, I am fine with adding backzone zones to the list, but 
I will probably revert the changes from 35fa37fbbb152f5d and 
0b925f6d8aaf927a from zone1970.tab, and work with that.

I will have to experiment with changing the code to parse the 
zone1970.tab country list, and break it up by that, showing only the 
country name and the comment in the selector.

-- 
\\// Peter - http://www.softwolves.pp.se/