Squashed 'tz/' changes from 9c175ec6c..a816a5c4d

efc5c0619 Release 2020e
b804a741d Improve doc of zic coalescing zone+DST transitions
c8891f390 Cite publication of Volgograd change
316c1598e Correct LMT and pre-1919 transitions for Nigeria
3dcdea78d Fix NEWS typo
c983a0fb7 Document zic coalescing zone+DST transitions
ce7b1bbc7 Seychelles switched from LMT to +04 on 1907-01-01
b980f1cac Model Turks & Caicos time 2015-2018 as AST
ff90fc93a Fix Vanuatu DST in 1973-1974 and 1984 transition
7c7419c6a Volgograd change likely December 27, not 20
0b5ae1fb7 Fix some errors in recent Bahamas changes
cd1769fe6 Fix Ghana again, for 1942 through 1946
3831c591e Fix Volgograd label in {zone,zone1970}.tab
adf4d8d35 Fix several pre-1946 transitions for Bahamas
0415d0e5f Re-fix Ghana typo for 1919/1920
6e7558f19 Fix Ghana typo for 1919/1920
271d9438b Volgograd switches from +04 to +03 on 12-20 02:00
a499dd6e0 * northamerica: Add URL for Yukon OIC 1980/02
7cc6d7c00 Fix several pre-1957 transitions for Ghana
17acee8cb Fix several pre-1957 transitions for Bermuda
1aca4cad3 Fix several pre-1972 transitions for Australia
a47ef9c71 * tz-link.html: Use <abbr> more systematically.
48e68fbfd Document "right" seconds better
beba17f43 Fix mistaken Belize interpretation
d7e93bdba Fix several Belize transitions 1942/1968
b231fbdb5 Port 'make rearguard_tarballs' to Solaris 10
8b21cc5d2 Fix Israel and Palestine transitions 1940/1985
52ba05422 Fix zone*.tab Yukon comment columns
b106a6e84 leapseconds now says why NIST, not IERS
eff0719a7 Fix Kenya transitions 1908/1960
78422f077 Use better fallback for unknown $(VERSION)
ac029805c * etcetera: Update comment in the light of Neil Fuller’s comments.
e4645c40a Port to downstream HP-UX-style ‘make’

git-subtree-dir: tz
git-subtree-split: a816a5c4de427cae12477455dea2bc4eb990b2c9

1 files changed, 36 insertions, 0 deletions

diff --git a/zic.8 b/zic.8
index dcd2fa3..60262d7 100644
--- a/zic.8
+++ b/zic.8
@@ -590,6 +590,42 @@ first transition into standard time.
 In a single zone it is an error if two rules take effect at the same
 instant, or if two zone changes take effect at the same instant.
 .PP
+If a continuation line subtracts
+.I N
+seconds from the UT offset after a transition that would be
+interpreted to be later if using the continuation line's UT offset and
+rules, the
+.q "until"
+time of the previous zone or continuation line is interpreted
+according to the continuation line's UT offset and rules, and any rule
+that would otherwise take effect in the next
+.I N
+seconds is instead assumed to take effect simultaneously.
+For example:
+.br
+.ne 7
+.nf
+.in +2m
+.ta \w'# Rule\0\0'u +\w'NAME\0\0'u +\w'FROM\0\0'u +\w'2006\0\0'u +\w'\*-\0\0'u +\w'Oct\0\0'u +\w'lastSun\0\0'u +\w'2:00\0\0'u +\w'SAVE\0\0'u
+.sp
+# Rule	NAME	FROM	TO	\*-	IN	ON	AT	SAVE	LETTER/S
+Rule	US	1967	2006	-	Oct	lastSun	2:00	0	S
+Rule	US	1967	1973	-	Apr	lastSun	2:00	1:00	D
+.ta \w'Zone\0\0America/Menominee\0\0'u +\w'STDOFF\0\0'u +\w'RULES\0\0'u +\w'FORMAT\0\0'u
+# Zone\0\0NAME	STDOFF	RULES	FORMAT	[UNTIL]
+Zone\0\0America/Menominee	\*-5:00	\*-	EST	1973 Apr 29 2:00
+	\*-6:00	US	C%sT
+.sp
+.in
+.fi
+Here, an incorrect reading would be there were two clock changes on 1973-04-29,
+the first from 02:00 EST (\*-05) to 01:00 CST (\*-06),
+and the second an hour later from 02:00 CST (\*-06) to 03:00 CDT (\*-05).
+However,
+.B zic
+interprets this more sensibly as a single transition from 02:00 CST (\*-05) to
+02:00 CDT (\*-05).
+.PP
 A link line has the form
 .sp
 .nf