Improve historical data for the Philippines

* NEWS: Mention this.
* asia (Phil, Asia/Manila): Correct transitions to match Selga
1923 and Philippine proclamations and orders.  (Thanks to P Chan.)
* zone.tab, zone1970.tab, zonenow.tab: Adjust Asia/Manila
coordinates to match longitude given by Selga 1923 and a likely
latitude to match, in the harbor.

NEWS

@@ -1,5 +1,21 @@
 News for the tz database
 
+Unreleased, experimental changes
+
+  Briefly:
+    Improve pre-1991 data for the Philippines.
+
+  Changes to past timestamps
+
+    Correct timestamps for the Philippines before 1900, and from 1937
+    through 1990.  (Thanks to P Chan for the heads-up and citations.)
+    This includes adjusting local mean time before 1899; fixing
+    transitions in September 1899, January 1937, and June 1954; adding
+    transitions in December 1941, November 1945, March and September
+    1977, and May and July 1990; and removing incorrect transitions in
+    March and September 1978.
+
+
 Release 2024b - 2024-09-04 12:27:47 -0700
 
   Briefly:

asia

@@ -3665,21 +3665,70 @@ Zone	Asia/Hebron	2:20:23	-	LMT	1900 Oct
 # be immediately followed by 1845-01-01; see R.H. van Gent's
 # History of the International Date Line
 # https://webspace.science.uu.nl/~gent0113/idl/idl_philippines.htm
-# The rest of the data entries are from Shanks & Pottenger.
-
-# From Jesper Nørgaard Welen (2006-04-26):
-# ... claims that Philippines had DST last time in 1990:
-# http://story.philippinetimes.com/p.x/ct/9/id/145be20cc6b121c0/cid/3e5bbccc730d258c/
-# [a story dated 2006-04-25 by Cris Larano of Dow Jones Newswires,
-# but no details]
-
-# From Paul Eggert (2014-08-14):
-# The following source says DST may be instituted November-January and again
-# March-June, but this is not definite.  It also says DST was last proclaimed
-# during the Ramos administration (1992-1998); but again, no details.
-# Carcamo D. PNoy urged to declare use of daylight saving time.
-# Philippine Star 2014-08-05
-# http://www.philstar.com/headlines/2014/08/05/1354152/pnoy-urged-declare-use-daylight-saving-time
+
+# From P Chan (2021-05-10):
+# Here's a fairly comprehensive article in Japanese:
+#	https://wiki.suikawiki.org/n/Philippine%20Time
+# (2021-05-16):
+# According to the references listed in the article,
+# the periods that the Philippines (Manila) observed DST or used +9 are:
+#
+# 1936-10-31 24:00 to 1937-01-15 24:00
+#	(Proclamation No. 104, Proclamation No. 126)
+# 1941-12-15 24:00 to 1945-11-30 24:00
+#	(Proclamation No. 789, Proclamation No. 20)
+# 1954-04-11 24:00 to 1954-06-04 24:00
+#	(Proclamation No. 13, Proclamation No. 33)
+# 1977-03-27 24:00 to 1977-09-21 24:00
+#	(Proclamation No. 1629, Proclamation No. 1641)
+# 1990-05-21 00:00 to 1990-07-28 24:00
+#	(National Emergency Memorandum Order No. 17, Executive Order No. 415)
+#
+# Proclamation No. 104 ... October 30, 1936
+#  https://www.officialgazette.gov.ph/1936/10/30/proclamation-no-104-s-1936/
+# Proclamation No. 126 ... January 15, 1937
+#  https://www.officialgazette.gov.ph/1937/01/15/proclamation-no-126-s-1937/
+# Proclamation No. 789 ... December 13, 1941
+#  https://www.officialgazette.gov.ph/1941/12/13/proclamation-no-789-s-1941/
+# Proclamation No. 20 ... November 11, 1945
+#  https://www.officialgazette.gov.ph/1945/11/11/proclamation-no-20-s-1945/
+# Proclamation No. 13 ... April 6, 1954
+#  https://www.officialgazette.gov.ph/1954/04/06/proclamation-no-13-s-1954/
+# Proclamation No. 33 ... June 3, 1954
+#  https://www.officialgazette.gov.ph/1954/06/03/proclamation-no-33-s-1954/
+# Proclamation No. 1629 ... March 25, 1977
+#  https://www.officialgazette.gov.ph/1977/03/25/proclamation-no-1629-s-1977/
+# Proclamation No. 1641 ...May 26, 1977
+#  https://www.officialgazette.gov.ph/1977/05/26/proclamation-no-1641-s-1977/
+# National Emergency Memorandum Order No. 17 ... May 2, 1990
+#  https://www.officialgazette.gov.ph/1990/05/02/national-emergency-memorandum-order-no-17-s-1990/
+# Executive Order No. 415 ... July 20, 1990
+#  https://www.officialgazette.gov.ph/1990/07/20/executive-order-no-415-s-1990/
+#
+# During WWII, Proclamation No. 789 fixed two periods of DST. The first period
+# was set to continue only until January 31, 1942. But Manila was occupied by
+# the Japanese earlier in the month....
+#
+# For the date of the adoption of standard time, Shank[s] gives 1899-05-11.
+# The article is not able to state the basis of that. I guess it was based on
+# a US War Department Circular issued on that date.
+#	https://books.google.com/books?id=JZ1PAAAAYAAJ&pg=RA3-PA8
+#
+# However, according to other sources, standard time was adopted on
+# 1899-09-06.  Also, the LMT was GMT+8:03:52
+#	https://books.google.com/books?id=MOYIAQAAIAAJ&pg=PA521
+#	https://books.google.com/books?id=lSnqqatpYikC&pg=PA21
+#
+# From Paul Eggert (2024-09-05):
+# The penultimate URL in P Chan's email refers to page 521 of
+# Selga M, The Time Service in the Philippines.
+# Proc Pan-Pacific Science Congress. Vol. 1 (1923), 519-532.
+# It says, "The change from the meridian 120° 58' 04" to the 120th implied a
+# change of 3 min. 52s.26 in time; consequently on 6th September, 1899,
+# Manila Observatory gave the noon signal 3 min. 52s.26 later than before".
+#
+# Wikipedia says the US declared Manila liberated on March 4, 1945;
+# this doesn't affect clocks, just our time zone abbreviation and DST flag.
 
 # From Paul Goyette (2018-06-15) with URLs updated by Guy Harris (2024-02-15):
 # In the Philippines, there is a national law, Republic Act No. 10535
@@ -3697,24 +3746,26 @@ Zone	Asia/Hebron	2:20:23	-	LMT	1900 Oct
 # influence of the sources.  There is no current abbreviation for DST,
 # so use "PDT", the usual American style.
 
-# From P Chan (2021-05-10):
-# Here's a fairly comprehensive article in Japanese:
-# https://wiki.suikawiki.org/n/Philippine%20Time
-# From Paul Eggert (2021-05-10):
-# The info in the Japanese table has not been absorbed (yet) below.
-
 # Rule	NAME	FROM	TO	-	IN	ON	AT	SAVE	LETTER/S
-Rule	Phil	1936	only	-	Nov	1	0:00	1:00	D
-Rule	Phil	1937	only	-	Feb	1	0:00	0	S
-Rule	Phil	1954	only	-	Apr	12	0:00	1:00	D
-Rule	Phil	1954	only	-	Jul	1	0:00	0	S
-Rule	Phil	1978	only	-	Mar	22	0:00	1:00	D
-Rule	Phil	1978	only	-	Sep	21	0:00	0	S
+Rule	Phil	1936	only	-	Oct	31	24:00	1:00	D
+Rule	Phil	1937	only	-	Jan	15	24:00	0	S
+Rule	Phil	1941	only	-	Dec	15	24:00	1:00	D
+# The following three rules were canceled by Japan:
+#Rule	Phil	1942	only	-	Jan	31	24:00	0	S
+#Rule	Phil	1942	only	-	Mar	 1	 0:00	1:00	D
+#Rule	Phil	1942	only	-	Jun	30	24:00	0	S
+Rule	Phil	1945	only	-	Nov	30	24:00	0	S
+Rule	Phil	1954	only	-	Apr	11	24:00	1:00	D
+Rule	Phil	1954	only	-	Jun	 4	24:00	0	S
+Rule	Phil	1977	only	-	Mar	27	24:00	1:00	D
+Rule	Phil	1977	only	-	Sep	21	24:00	0	S
+Rule	Phil	1990	only	-	May	21	 0:00	1:00	D
+Rule	Phil	1990	only	-	Jul	28	24:00	0	D
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Asia/Manila	-15:56:00 -	LMT	1844 Dec 31
-			8:04:00 -	LMT	1899 May 11
-			8:00	Phil	P%sT	1942 May
-			9:00	-	JST	1944 Nov
+Zone	Asia/Manila	-15:56:08 -	LMT	1844 Dec 31
+			8:03:52 -	LMT	1899 Sep  6  4:00u
+			8:00	Phil	P%sT	1942 Feb 11 24:00
+			9:00	-	JST	1945 Mar  4
 			8:00	Phil	P%sT
 
 # Bahrain

zone.tab

@@ -310,7 +310,7 @@ PF	-0900-13930	Pacific/Marquesas	Marquesas Islands
 PF	-2308-13457	Pacific/Gambier	Gambier Islands
 PG	-0930+14710	Pacific/Port_Moresby	most of Papua New Guinea
 PG	-0613+15534	Pacific/Bougainville	Bougainville
-PH	+1435+12100	Asia/Manila
+PH	+143512+1205804	Asia/Manila
 PK	+2452+06703	Asia/Karachi
 PL	+5215+02100	Europe/Warsaw
 PM	+4703-05620	America/Miquelon

zone1970.tab

@@ -246,7 +246,7 @@ PF	-0900-13930	Pacific/Marquesas	Marquesas Islands
 PF	-2308-13457	Pacific/Gambier	Gambier Islands
 PG,AQ,FM	-0930+14710	Pacific/Port_Moresby	Papua New Guinea (most areas), Chuuk, Yap, Dumont d'Urville
 PG	-0613+15534	Pacific/Bougainville	Bougainville
-PH	+1435+12100	Asia/Manila
+PH	+143512+1205804	Asia/Manila
 PK	+2452+06703	Asia/Karachi
 PL	+5215+02100	Europe/Warsaw
 PM	+4703-05620	America/Miquelon

zonenow.tab

@@ -236,7 +236,7 @@ XX	+3114+12128	Asia/Shanghai	China ("CST")
 XX	+2217+11409	Asia/Hong_Kong	Hong Kong ("HKT")
 #
 # +08 - PHT
-XX	+1435+12100	Asia/Manila	Philippines ("PHT")
+XX	+143512+1205804	Asia/Manila	Philippines ("PHT")
 #
 # +08 - WITA
 XX	-0507+11924	Asia/Makassar	Indonesia ("WITA")