[tz] Fwd: DST changes in Hungary (full historical revision)

[Paul Eggert]

Thanks for those corrections. I installed the attached patch to the development
database on GitHub. It's not exactly what you emailed me, but it should generate
equivalent transitions.

It'd help if we could list citations for the transitions; are URLs available for
each decree etc. that you consulted? We could add them as comments.

Thanks again.
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From f87ed56dae304043e45c7cdbcff88de02b34fed4 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert at cs.ucla.edu>
Date: Sun, 7 Jun 2020 16:22:24 -0700
Subject: [PATCH] Fix Hungarian transitions 1918-1983
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

(Thanks to Géza Nyáry.)
* NEWS: Mention this.
* europe (Hungary, Europe/Budapest): Update transitions.
---
 NEWS   |  6 ++++++
 europe | 49 +++++++++++++++++++++++++------------------------
 2 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/NEWS b/NEWS
index 8362dcc..91ab463 100644
--- a/NEWS
+++ b/NEWS
@@ -9,6 +9,12 @@ Unreleased, experimental changes
     (Thanks to Milamber.)  The first altered prediction is for 2023,
     now predicted to spring-forward on April 30 instead of April 23.
 
+  Changes to past timestamps
+
+    Correct several transitions for Hungary for 1918/1983.
+    For example, the 1983-09-25 fall-back was at 01:00, not 03:00.
+    (Thanks to Géza Nyáry.)
+
   Changes to code
 
     The undocumented and ineffective tzsetwall function has been
diff --git a/europe b/europe
index 698a7ba..48e1eeb 100644
--- a/europe
+++ b/europe
@@ -1511,38 +1511,39 @@ Zone	Europe/Athens	1:34:52 -	LMT	1895 Sep 14
 			2:00	EU	EE%sT
 
 # Hungary
-# From Paul Eggert (2014-07-15):
-# Dates for 1916-1945 are taken from:
-# Oross A. Jelen a múlt jövője: a nyári időszámítás Magyarországon 1916-1945.
-# National Archives of Hungary (2012-10-29).
-# http://mnl.gov.hu/a_het_dokumentuma/a_nyari_idoszamitas_magyarorszagon_19161945.html
-# This source does not always give times, which are taken from Shanks
-# & Pottenger (which disagree about the dates).
+# From Géza Nyáry (2020-06-07):
+# Data for 1918-1983 are based on the archive database of Library Hungaricana.
+# The dates are collected from original, scanned governmental orders,
+# bulletins, instructions and public press.
+# https://library.hungaricana.hu
+# For example, the 1920 dates are from ministerial decree 1920.évi.2.254.
+
 # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
-Rule	Hungary	1918	only	-	Apr	 1	 3:00	1:00	S
-Rule	Hungary	1918	only	-	Sep	16	 3:00	0	-
-Rule	Hungary	1919	only	-	Apr	15	 3:00	1:00	S
-Rule	Hungary	1919	only	-	Nov	24	 3:00	0	-
+Rule	Hungary	1918	1919	-	Apr	15	 2:00	1:00	S
+Rule	Hungary	1918	1920	-	Sep	Mon>=15	 3:00	0	-
+Rule	Hungary	1920	only	-	Apr	 5	 2:00	1:00	S
 Rule	Hungary	1945	only	-	May	 1	23:00	1:00	S
-Rule	Hungary	1945	only	-	Nov	 1	 0:00	0	-
+Rule	Hungary	1945	only	-	Nov	 1	 1:00	0	-
 Rule	Hungary	1946	only	-	Mar	31	 2:00s	1:00	S
-Rule	Hungary	1946	1949	-	Oct	Sun>=1	 2:00s	0	-
+Rule	Hungary	1946	only	-	Oct	 7	 2:00	0	-
 Rule	Hungary	1947	1949	-	Apr	Sun>=4	 2:00s	1:00	S
-Rule	Hungary	1950	only	-	Apr	17	 2:00s	1:00	S
-Rule	Hungary	1950	only	-	Oct	23	 2:00s	0	-
-Rule	Hungary	1954	1955	-	May	23	 0:00	1:00	S
-Rule	Hungary	1954	1955	-	Oct	 3	 0:00	0	-
-Rule	Hungary	1956	only	-	Jun	Sun>=1	 0:00	1:00	S
-Rule	Hungary	1956	only	-	Sep	lastSun	 0:00	0	-
-Rule	Hungary	1957	only	-	Jun	Sun>=1	 1:00	1:00	S
-Rule	Hungary	1957	only	-	Sep	lastSun	 3:00	0	-
-Rule	Hungary	1980	only	-	Apr	 6	 1:00	1:00	S
+Rule	Hungary	1947	1949	-	Oct	Sun>=1	 2:00s	0	-
+Rule	Hungary	1954	only	-	May	23	 0:00	1:00	S
+Rule	Hungary	1954	only	-	Oct	 3	 0:00	0	-
+Rule	Hungary	1955	only	-	May	22	 2:00	1:00	S
+Rule	Hungary	1955	only	-	Oct	 2	 3:00	0	-
+Rule	Hungary	1956	1957	-	Jun	Sun>=1	 2:00	1:00	S
+Rule	Hungary	1956	1957	-	Sep	lastSun	 3:00	0	-
+Rule	Hungary	1980	only	-	Apr	 6	 0:00	1:00	S
+Rule	Hungary	1980	only	-	Sep	28	 1:00	0	-
+Rule	Hungary	1981	1983	-	Mar	lastSun	 0:00	1:00	S
+Rule	Hungary	1981	1983	-	Sep	lastSun	 1:00	0	-
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Budapest	1:16:20 -	LMT	1890 Oct
 			1:00	C-Eur	CE%sT	1918
-			1:00	Hungary	CE%sT	1941 Apr  8
+			1:00	Hungary	CE%sT	1941 Apr  7 23:00
 			1:00	C-Eur	CE%sT	1945
-			1:00	Hungary	CE%sT	1980 Sep 28  2:00s
+			1:00	Hungary	CE%sT	1984
 			1:00	EU	CE%sT
 
 # Iceland
-- 
2.17.1