For the period from 1919 Jul 1 2:00 to 1922 Oct in the Europe/Moscow zone the Europe file says to apply the Russia rules with the format MSK/MSD: 2:30:48 Russia %s 1919 Jul 1 2:00 3:00 Russia MSK/MSD 1922 Oct However, the Russia rules show three different offsets during 1921, 0, +1 and +2: Rule Russia 1919 only - Aug 16 0:00 0 - Rule Russia 1921 only - Feb 14 23:00 1:00 S Rule Russia 1921 only - Mar 20 23:00 2:00 M # Midsummer Rule Russia 1921 only - Sep 1 0:00 1:00 S Rule Russia 1921 only - Oct 1 0:00 0 -