Hi, The rules for Finland say that summer time was in force in 1942 from Apr 3 to Oct 3: # Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S Rule Finland 1942 only - Apr 3 0:00 1:00 S Rule Finland 1942 only - Oct 3 0:00 0 - However, http://almanakka.helsinki.fi/images/aikakirja/Aikakirja2013kokonaan.pdf pages 104-105, including a scan from a newspaper published on Apr 2 1942 say that it should be Oct 4, not Oct 3. On Apr 2 1942, 24 o’clock (which means Apr 3 1942, 0:00 o’clock), clocks were moved one hour forward. The newspaper mentions “on the night from Thursday to Friday”. The tz entry is correct for the start of the daylight saving time. On Oct 4 1942, clocks were moved at 1:00 one hour backwards. The tz entry should be corrected. Apparently not only the date, but also the time of day is wrong in the entry. Hope this helps. Konstantin Hyppönen