[tz] [PATCH 1/3] Fix off-by-one bug with Kingston Mean Time.

[Paul Eggert]

* northamerica (America/Cayman, America/Jamaica, America/Grand_Turk):
Change KMT from -5:07:12 to -5:07:11 (should be -5:07:10.41).
* zone.tab: Fine-tune geographical coordinates to match -5:07:10.41.
I chose the latitude to match the General Post Office, Kingston,
in the city center according to Google Maps.
---
 northamerica | 19 +++++++------------
 zone.tab     |  2 +-
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/northamerica b/northamerica
index 3a572ba..55755dd 100644
--- a/northamerica
+++ b/northamerica
@@ -2622,7 +2622,7 @@ Zone Atlantic/Bermuda    -4:19:18 -    LMT    1930
Jan  1 2:00    # Hamilton
 # Cayman Is
 # Zone    NAME        GMTOFF    RULES    FORMAT    [UNTIL]
 Zone    America/Cayman    -5:25:32 -    LMT    1890        # Georgetown
-            -5:07:12 -    KMT    1912 Feb    # Kingston Mean Time
+            -5:07:11 -    KMT    1912 Feb    # Kingston Mean Time
             -5:00    -    EST
 
 # Costa Rica
@@ -3067,17 +3067,12 @@ Zone America/Tegucigalpa -5:48:52 -    LMT  
 1921 Apr
 # Great Swan I ceded by US to Honduras in 1972
 
 # Jamaica
-
-# From Bob Devine (1988-01-28):
-# Follows US rules.
-
-# From U. S. Naval Observatory (1989-01-19):
-# JAMAICA             5 H  BEHIND UTC
-
-# From Shanks & Pottenger:
+# Shanks & Pottenger give -5:07:12, but Milne records -5:07:10.41 from an
+# unspecified official document, and says "This time is used throughout the
+# island".  Go with Milne.  Round to the nearest second as required by zic.
 # Zone    NAME        GMTOFF    RULES    FORMAT    [UNTIL]
-Zone    America/Jamaica    -5:07:12 -    LMT    1890        # Kingston
-            -5:07:12 -    KMT    1912 Feb    # Kingston Mean Time
+Zone    America/Jamaica    -5:07:11 -    LMT    1890        # Kingston
+            -5:07:11 -    KMT    1912 Feb    # Kingston Mean Time
             -5:00    -    EST    1974 Apr 28 2:00
             -5:00    US    E%sT    1984
             -5:00    -    EST
@@ -3217,7 +3212,7 @@ Rule    TC    2007    max    -    Mar    Sun>=8  
 2:00    1:00    D
 Rule    TC    2007    max    -    Nov    Sun>=1    2:00    0    S
 # Zone    NAME        GMTOFF    RULES    FORMAT    [UNTIL]
 Zone America/Grand_Turk    -4:44:32 -    LMT    1890
-            -5:07:12 -    KMT    1912 Feb    # Kingston Mean Time
+            -5:07:11 -    KMT    1912 Feb    # Kingston Mean Time
             -5:00    TC    E%sT
 
 # British Virgin Is
diff --git a/zone.tab b/zone.tab
index 769432b..7d4c575 100644
--- a/zone.tab
+++ b/zone.tab
@@ -233,7 +233,7 @@ IR    +3540+05126    Asia/Tehran
 IS    +6409-02151    Atlantic/Reykjavik
 IT    +4154+01229    Europe/Rome
 JE    +4912-00207    Europe/Jersey
-JM    +1800-07648    America/Jamaica
+JM    +175805-0764736    America/Jamaica
 JO    +3157+03556    Asia/Amman
 JP    +353916+1394441    Asia/Tokyo
 KE    -0117+03649    Africa/Nairobi
-- 
1.8.3.1