On 2018-02-16 17:58, Paul Eggert proposed:
+# ....... Assume transitions at 24:00 on the specified days until Ley No.The proposed date of the switch, 1926-03-06, would be before the publication
+# 7919 of 1926-03-05 ended this arrangement, repealing all "laws and other
+# provisions which oppose" it, resulting immediately in year-round UT-03:30.
+# (Since we don't know the time at which the change became law, assume clocks
+# were changed at 24:00 that evening. Almanaque 2018 is a bit hand-wavey here,
+# anyway.)
+#.......
+# https://www.impo.com.uy/diariooficial/1926/03/10/2
+#.......
+Rule Uruguay 1926 only - Mar 5 24:00 0 -
of the law, which seems to be unlikely. Anyway, the Almanaque 2018 explicitly
says that the switch was on 1926-04-01, the date specified by the law of 1923,
and so does the Resolución of 1926-03-11 published in
[http://www.impo.com.uy/diariooficial/1926/03/18/2 ].
I propose that tzdb follow these sources, rather than make an estimate.
Michael Deckers.