[tz] [PROPOSED] Sub-second history for Maputo and Zurich

[Paul Eggert]

* africa (Africa/Maputo), europe (Europe/Zurich): Add #STDOFF
comments for two zones with well-sourced standard time that was
not an integral number of seconds away from UT.  This does not
change the TZif output files.
---
 africa | 5 +++--
 europe | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/africa b/africa
index 695d66ed..4f0d1e7b 100644
--- a/africa
+++ b/africa
@@ -1101,11 +1101,11 @@ Zone Africa/El_Aaiun	-0:52:48 -	LMT	1934 Jan # El Aaiún
 # Zambia
 # Zimbabwe
 #
-# From Paul Eggert (2024-04-09):
+# From Paul Eggert (2024-05-24):
 # The London Gazette, 1903-04-03, page 2245, says that
 # as of 1903-03-03 a time ball at the port of Lourenço Marques
 # (as Maputo was then called) was dropped daily at 13:00:00 LMT,
-# corresponding to 22:49:41.7 GMT; round this to UT+2:10:18.
+# corresponding to 22:49:41.7 GMT, so local time was +02:10:18.3.
 # Conversely, the newspaper South Africa, 1909-02-09, page 321,
 # says the port had just installed an apparatus that communicated
 # "from the controlling clock in the new Observatory at Reuben Point ...
@@ -1116,6 +1116,7 @@ Zone Africa/El_Aaiun	-0:52:48 -	LMT	1934 Jan # El Aaiún
 # For lack of better info, list 1909 as the transition date.
 #
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
+		#STDOFF	2:10:18.3
 Zone	Africa/Maputo	2:10:18 -	LMT	1909
 			2:00	-	CAT
 
diff --git a/europe b/europe
index 9ea14914..2f180e64 100644
--- a/europe
+++ b/europe
@@ -3486,8 +3486,8 @@ Zone	Atlantic/Canary	-1:01:36 -	LMT	1922 Mar # Las Palmas de Gran C.
 # but if no one is present after 11 at night, could be postponed until one
 # hour before the beginning of service.
 
-# From Paul Eggert (2013-09-11):
-# Round BMT to the nearest even second, 0:29:46.
+# From Paul Eggert (2024-05-24):
+# Express BMT as 0:29:45.500, approximately the same precision 7° 26' 22.50".
 #
 # We can find no reliable source for Shanks's assertion that all of Switzerland
 # except Geneva switched to Bern Mean Time at 00:00 on 1848-09-12.  This book:
@@ -3526,6 +3526,7 @@ Rule	Swiss	1941	1942	-	May	Mon>=1	1:00	1:00	S
 Rule	Swiss	1941	1942	-	Oct	Mon>=1	2:00	0	-
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Europe/Zurich	0:34:08 -	LMT	1853 Jul 16 # See above comment.
+		#STDOFF	0:29:45.500
 			0:29:46	-	BMT	1894 Jun    # Bern Mean Time
 			1:00	Swiss	CE%sT	1981
 			1:00	EU	CE%sT
-- 
2.43.0