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<p class="MsoNormal">Dear all,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I was looking at some Unicode ICU test failure on Ubuntu related to time zone.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">ICU utilizes TZ database including backward file. In backward file, Europe/Tiraspol is defined as a link of Europe/Chisinau. So the actual rule is coming from Europe/Chisinau as below (2023c)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"># Zone NAME STDOFF RULES FORMAT [UNTIL]<o:p></o:p></p>
<p class="MsoNormal">Zone Europe/Chisinau 1:55:20 - LMT 1880<o:p></o:p></p>
<p class="MsoNormal"> 1:55 - CMT 1918 Feb 15 # Chisinau MT<o:p></o:p></p>
<p class="MsoNormal"> 1:44:24 - BMT 1931 Jul 24 # Bucharest MT<o:p></o:p></p>
<p class="MsoNormal"> 2:00 Romania EE%sT 1940 Aug 15<o:p></o:p></p>
<p class="MsoNormal"> 2:00 1:00 EEST 1941 Jul 17<o:p></o:p></p>
<p class="MsoNormal"> 1:00 C-Eur CE%sT 1944 Aug 24<o:p></o:p></p>
<p class="MsoNormal"> 3:00 Russia MSK/MSD 1990 May 6 2:00<o:p></o:p></p>
<p class="MsoNormal"> 2:00 Russia EE%sT 1992<o:p></o:p></p>
<p class="MsoNormal"> 2:00 E-Eur EE%sT 1997<o:p></o:p></p>
<p class="MsoNormal"># See Romania commentary for the guessed 1997 transition to EU rules.<o:p></o:p></p>
<p class="MsoNormal"> 2:00 Moldova EE%sT<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I found behavior of Europe/Tiraspol is different on Ubuntu. When I set Europe/Tiraspol as the system time zone, the default offset set to timezone variable becomes -10800 (3 hour ahead of UTC). However, Europe/Chisinau above shows it should
be -7200 (2 hour ahead of UTC) at this moment. (POSIX timezone variable should store “standard offset”, not counting daylight adjustment).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">On Ubuntu, when I set Europe/Tiraspol as system time zone, -10800 is set to timezone variable. However, when I set Europe/Chisinau, it changes to -7200. Then I realized Ubuntu is using backzone file, which contains different rule.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In backzone file, Europe/Tiraspol is defined as below (2023c)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"># Moldova / Transnistria<o:p></o:p></p>
<p class="MsoNormal">Zone Europe/Tiraspol 1:58:32 - LMT 1880<o:p></o:p></p>
<p class="MsoNormal"> 1:55 - CMT 1918 Feb 15 # Chisinau MT<o:p></o:p></p>
<p class="MsoNormal"> 1:44:24 - BMT 1931 Jul 24 # Bucharest MT<o:p></o:p></p>
<p class="MsoNormal"> 2:00 Romania EE%sT 1940 Aug 15<o:p></o:p></p>
<p class="MsoNormal"> 2:00 1:00 EEST 1941 Jul 17<o:p></o:p></p>
<p class="MsoNormal"> 1:00 C-Eur CE%sT 1944 Aug 24<o:p></o:p></p>
<p class="MsoNormal"> 3:00 Russia MSK/MSD 1991 Mar 31 2:00<o:p></o:p></p>
<p class="MsoNormal"> 2:00 Russia EE%sT 1992 Jan 19 2:00<o:p></o:p></p>
<p class="MsoNormal"> 3:00 Russia MSK/MSD<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I understand backzone was created for preserving zone definition of some locations which only differs pre-1970 date, and these data might not be reliable. In reality, I think most of TZ database consumer still rely on either backward or
backzone for backward compatibility. I think it’s problematic if these two files produce different results today.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I guess the zone definition in backzone file might be outdated, and Tiraspol is actually UTC+2/+3.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">-Yoshito<o:p></o:p></p>
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