[tz] Europe/Moscow

[Paul Eggert]

Hank W. wrote:
> I was referring to the following line, "UNTIL 1922 Oct".

Ah, thanks, I see the problem now.  I pushed the proposed patch into the 
experimental github version.
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From 8d558674ce15736f4db98332e9d1e86b1555c340 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert at cs.ucla.edu>
Date: Sat, 31 May 2014 15:37:07 -0700
Subject: [PATCH] * europe (Russia, Europe/Moscow): Use "MSM" for Moscow
 Midsummer Time

in 1921.  (Thanks to Hank W. for reporting the problem.)
Also, update a stale URL.
* NEWS: Document the Moscow change.
---
 NEWS   |  8 ++++++++
 europe | 25 +++++++++++++------------
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/NEWS b/NEWS
index d2a7e9a..583c472 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,13 @@
 News for the tz database
 
+Unreleased, experimental changes
+
+  Changes affecting past time stamps
+
+    The abbreviation "MSM" (Moscow Midsummer Time) is now used instead of
+    "MSD" for Moscow's double daylight time in summer 1921.
+    (Thanks to Hank W. for reporting the problem.)
+
 
 Release 2014d - 2014-05-27 21:34:40 -0700
 
diff --git a/europe b/europe
index bfc596a..3a49ca2 100644
--- a/europe
+++ b/europe
@@ -6,7 +6,7 @@
 # go ahead and edit the file (and please send any changes to
 # tz at iana.org for general use in the future).
 
-# From Paul Eggert (2006-03-22):
+# From Paul Eggert (2014-05-31):
 # A good source for time zone historical data outside the U.S. is
 # Thomas G. Shanks and Rique Pottenger, The International Atlas (6th edition),
 # San Diego: ACS Publications, Inc. (2003).
@@ -17,6 +17,9 @@
 # published semiannually.  Law sent in several helpful summaries
 # of the IATA's data after 1990.
 #
+# A reliable and entertaining source about time zones is
+# Derek Howse, Greenwich time and longitude, Philip Wilson Publishers (1997).
+#
 # Except where otherwise noted, Shanks & Pottenger is the source for
 # entries through 1991, and IATA SSIM is the source for entries afterwards.
 #
@@ -26,9 +29,9 @@
 #	Whitman Publishing Co, 2 Niagara Av, Ealing, London (undated),
 #	which I found in the UCLA library.
 #
-#	<a href="http://www.pettswoodvillage.co.uk/Daylight_Savings_William_Willett.pdf">
 #	William Willett, The Waste of Daylight, 19th edition
-#	</a> (1914-03)
+#	<http://cs.ucla.edu/~eggert/Daylight_Savings_William_Willett.pdf>
+#	[PDF] (1914-03)
 #
 #	Milne J. Civil time. Geogr J. 1899 Feb;13(2):173-94
 #	<http://www.jstor.org/stable/1774359>.  He writes:
@@ -58,10 +61,7 @@
 #        1:00       CET CEST CEMT Central Europe
 #        1:00:14    SET           Swedish (1879-1899)*
 #        2:00       EET EEST      Eastern Europe
-#        3:00       MSK MSD       Moscow
-#
-# A reliable and entertaining source about time zones, especially in Britain,
-# Derek Howse, Greenwich time and longitude, Philip Wilson Publishers (1997).
+#        3:00       MSK MSD  MSM* Moscow
 
 # From Peter Ilieve (1994-12-04),
 # The original six [EU members]: Belgium, France, (West) Germany, Italy,
@@ -558,11 +558,11 @@ Rule	Russia	1917	only	-	Dec	28	 0:00	0	MMT	# Moscow Mean Time
 Rule	Russia	1918	only	-	May	31	22:00	2:00	MDST	# Moscow Double Summer Time
 Rule	Russia	1918	only	-	Sep	16	 1:00	1:00	MST
 Rule	Russia	1919	only	-	May	31	23:00	2:00	MDST
-Rule	Russia	1919	only	-	Jul	 1	 2:00	1:00	S
-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	1919	only	-	Jul	 1	 2:00	1:00	MSD
+Rule	Russia	1919	only	-	Aug	16	 0:00	0	MSK
+Rule	Russia	1921	only	-	Feb	14	23:00	1:00	MSD
+Rule	Russia	1921	only	-	Mar	20	23:00	2:00	MSM # Midsummer
+Rule	Russia	1921	only	-	Sep	 1	 0:00	1:00	MSD
 Rule	Russia	1921	only	-	Oct	 1	 0:00	0	-
 # Act No.925 of the Council of Ministers of the USSR (1980-10-24):
 Rule	Russia	1981	1984	-	Apr	 1	 0:00	1:00	S
@@ -2217,6 +2217,7 @@ Zone Europe/Kaliningrad	 1:22:00 -	LMT	1893 Apr
 Zone Europe/Moscow	 2:30:20 -	LMT	1880
 			 2:30	-	MMT	1916 Jul  3 # Moscow Mean Time
 			 2:30:48 Russia	%s	1919 Jul  1 2:00
+			 3:00	Russia	%s	1921 Oct
 			 3:00	Russia	MSK/MSD	1922 Oct
 			 2:00	-	EET	1930 Jun 21
 			 3:00	Russia	MSK/MSD	1991 Mar 31 2:00s
-- 
1.9.1