Re: POSIX TS spec reverses the meaning of TZ offset compared to ISO

[Max Nikulin]

On 02/02/2023 16:37, Heinz Tuechler wrote:
> tomas wrote/hat geschrieben on/am 02.02.2023 09:33:
> > On Thu, Feb 02, 2023 at 08:45:51AM +0100, Heinz Tuechler wrote:
> > > It seems to me that this shows the time zone I selected at set up of the
> > > computer, in my case Europe/Berlin. Using package lutz in R with correct
> > > coordinates I see Europe/Vienna, based on open street map.
> > > Days ago I did not even know that Berlin and Vienna are in different
> > > time zones.

It is not uncommon problem. People set a time zone having the same 
offset and later complain that historical data can not be trusted.

Ubuntu guesses timezone likely using their GeoIP service. For me it 
works correctly. Approach implemented in Debian installer can be called 
at least questionable. They allows to choose from incomplete subset of 
time zones that is based on locale (selected several steps before). 
Developers refuse requests to add an option with complete list of time 
zones. So some users either finishes with incorrect time zone or have to 
run dpkg-reconfigure tzdata.

I forgot to mention some methods to guess location and so time zone when 
I was writing https://list.orgmode.org/orgmode/tqj9af$vhk$1@ciao.gmane.io/

> > Vienna is special :)

There is no reason to add a timezone if there is nothing special.

zdump -v Europe/Berlin

Europe/Berlin  Sun Sep 28 00:59:59 1980 UT = Sun Sep 28 02:59:59 1980 
CEST isdst=1 gmtoff=7200
Europe/Berlin  Sun Sep 28 01:00:00 1980 UT = Sun Sep 28 02:00:00 1980 
CET isdst=0 gmtoff=3600

zdump -v Europe/Vienna

Europe/Vienna  Sat Sep 27 21:59:59 1980 UT = Sat Sep 27 23:59:59 1980 
CEST isdst=1 gmtoff=7200
Europe/Vienna  Sat Sep 27 22:00:00 1980 UT = Sat Sep 27 23:00:00 1980 
CET isdst=0 gmtoff=3600

03:00 -> 02:00 vs 24:00 -> 23:00 transition time.