Re: [HACKERS] Time zones

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> The most recent atlas I have says that eastern Alaska is GMT-9,
> western Alaska and Hawaii are GMT-10, and the westernmost Aleutians
> are GMT-11. No info about daylight savings habits. A ten-year-old
> atlas claims that all of mainland Alaska is GMT-9. They may have
> changed things up there recently ... I think we need a native
> guide ...

...or just Olson. Here are the relevant bits I find in the zoneinfo
library. The GMTOFF column is the basic (non-DST) offset, RULES is
"-" if there's no DST, the constant "1:00" for the three week period
of the 1933 Hawaiian DST experiment, and "US" to indicate that DST is
used, and follows the US rules I append at the bottom of the list. In
this case, the FORMAT column has a "%s" that's replaced by the
relevant letter ("S", "W" or "D") from the LETTERS column of the rule.

So, getting back to what someone (Thomas Lockhart?) said:

> I want to confirm that AHST, Alaska-Hawaii Std Time, should have the
> same value as Australia Eastern Std Time, which is what the
> conversion table claims.

I think not. AH[SD]T used to cover Hawaii and parts of Alaska, but
nowadays it's just parts of Alaska. Eastern Australia is another four
hours west, over on the other side of the date line, at +10:00 instead
of -10:00.

# Zone NAME GMTOFF RULES FORMAT [UNTIL]
Zone Pacific/Honolulu -10:31:26 - LMT 1900 Jan 1 12:00
-10:30 - HST 1933 Apr 30 2:00
-10:30 1:00 HDT 1933 May 21 2:00
-10:30 US H%sT 1947 Jun 8 2:00
-10:00 - HST

# Zone NAME GMTOFF RULES FORMAT [UNTIL]
Zone America/Juneau -8:57:41 - LMT 1900 Aug 20 12:00
-8:00 - PST 1942
-8:00 US P%sT 1946
-8:00 - PST 1969
-8:00 US P%sT 1983 Oct 30 2:00
-9:00 US AK%sT
Zone America/Yakutat -9:18:55 - LMT 1900 Aug 20 12:00
-9:00 - YST 1942
-9:00 US Y%sT 1946
-9:00 - YST 1969
-9:00 US Y%sT 1983 Oct 30 2:00
-9:00 US AK%sT
Zone America/Anchorage -9:59:36 - LMT 1900 Aug 20 12:00
-10:00 - CAT 1942
-10:00 US CAT/CAWT 1946
-10:00 - CAT 1967 Apr
-10:00 - AHST 1969
-10:00 US AH%sT 1983 Oct 30 2:00
-9:00 US AK%sT
Zone America/Nome -11:01:38 - LMT 1900 Aug 20 12:00
-11:00 - NST 1942
-11:00 US N%sT 1946
-11:00 - NST 1967 Apr
-11:00 - BST 1969
-11:00 US B%sT 1983 Oct 30 2:00
-9:00 US AK%sT
Zone America/Adak -11:46:38 - LMT 1900 Aug 20 12:00
-11:00 - NST 1942
-11:00 US N%sT 1946
-11:00 - NST 1967 Apr
-11:00 - BST 1969
-11:00 US B%sT 1983 Oct 30 2:00
-10:00 US HA%sT

# Rule NAME FROM TO TYPE IN ON AT SAVE LETTER/S
Rule US 1918 1919 - Mar lastSun 2:00 1:00 W # War
Rule US 1918 1919 - Oct lastSun 2:00 0 S
Rule US 1942 only - Feb 9 2:00 1:00 W # War
Rule US 1945 only - Sep 30 2:00 0 S
Rule US 1967 max - Oct lastSun 2:00 0 S
Rule US 1967 1973 - Apr lastSun 2:00 1:00 D
Rule US 1974 only - Jan 6 2:00 1:00 D
Rule US 1975 only - Feb 23 2:00 1:00 D
Rule US 1976 1986 - Apr lastSun 2:00 1:00 D
Rule US 1987 max - Apr Sun>=1 2:00 1:00 D

-tih
--
Popularity is the hallmark of mediocrity. --Niles Crane, "Frasier"