[tz] [PROPOSED] Be more consistent about MSK/MSD

[Paul Eggert]

* NEWS: Mention this.
* europe (Europe/Volgograd, Europe/Kirov): Use the abbreviations
MSK/MSD when using Moscow time, since that’s what other Russian
timezones do.  This fixes an inconsistency introduced in 2016g.
---
 NEWS   |  6 ++++++
 europe | 18 +++++++++---------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/NEWS b/NEWS
index 7bd80803..fc35046c 100644
--- a/NEWS
+++ b/NEWS
@@ -26,6 +26,12 @@ Unreleased, experimental changes
     since 1970.  (Thanks to Almaz Mingaleev.)  This affects some
     pre-1948 timestamps.  The old data are now in 'backzone'.
 
+  Changes to past time zone abbreviations
+
+    When observing Moscow time, Europe/Kirov and Europe/Volgograd now
+    use the abbreviations MSK/MSD instead of numeric abbreviations,
+    for consistency with other timezones observing Moscow time.
+
   Changes to code
 
     You can now tell tzselect local time, to simplify later choices.
diff --git a/europe b/europe
index 89bc3a28..b784d0ee 100644
--- a/europe
+++ b/europe
@@ -2656,13 +2656,13 @@ Zone Europe/Volgograd	 2:57:40 -	LMT	1920 Jan  3
 			 3:00	-	+03	1930 Jun 21
 			 4:00	-	+04	1961 Nov 11
 			 4:00	Russia	+04/+05	1988 Mar 27  2:00s
-			 3:00	Russia	+03/+04	1991 Mar 31  2:00s
+			 3:00	Russia	MSK/MSD	1991 Mar 31  2:00s
 			 4:00	-	+04	1992 Mar 29  2:00s
-			 3:00	Russia	+03/+04	2011 Mar 27  2:00s
-			 4:00	-	+04	2014 Oct 26  2:00s
-			 3:00	-	+03	2018 Oct 28  2:00s
+			 3:00	Russia	MSK/MSD	2011 Mar 27  2:00s
+			 4:00	-	MSK	2014 Oct 26  2:00s
+			 3:00	-	MSK	2018 Oct 28  2:00s
 			 4:00	-	+04	2020 Dec 27  2:00s
-			 3:00	-	+03
+			 3:00	-	MSK
 
 # From Paul Eggert (2016-11-11):
 # Europe/Saratov covers:
@@ -2693,11 +2693,11 @@ Zone Europe/Saratov	 3:04:18 -	LMT	1919 Jul  1  0:00u
 Zone Europe/Kirov	 3:18:48 -	LMT	1919 Jul  1  0:00u
 			 3:00	-	+03	1930 Jun 21
 			 4:00	Russia	+04/+05	1989 Mar 26  2:00s
-			 3:00	Russia	+03/+04	1991 Mar 31  2:00s
+			 3:00	Russia	MSK/MSD	1991 Mar 31  2:00s
 			 4:00	-	+04	1992 Mar 29  2:00s
-			 3:00	Russia	+03/+04	2011 Mar 27  2:00s
-			 4:00	-	+04	2014 Oct 26  2:00s
-			 3:00	-	+03
+			 3:00	Russia	MSK/MSD	2011 Mar 27  2:00s
+			 4:00	-	MSK	2014 Oct 26  2:00s
+			 3:00	-	MSK
 
 # From Tim Parenti (2014-07-03), per Oscar van Vlijmen (2001-08-25):
 # Europe/Samara covers...
-- 
2.37.2