I'm writing up the full set of allowed date/time formats, and thought
I'd include the recognized time zones.

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. Seems to me that it is on the wrong side of the date line.
Does someone know what the correct value is?

                  - Tom

Fri, 15 Jan 1999 05:36:04 +0000
"Thomas G. Lockhart" <lockhart@alumni.caltech.edu>
Time zones
Australian Eastern Std Time is GMT-10. Alaska and Hawaii are
definitely on the other side of the dateline. They should not be the
same.

On Fri, 15 Jan 1999, Thomas G. Lockhart wrote:

> I'm writing up the full set of allowed date/time formats, and thought
> I'd include the recognized time zones.
> 
> 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. Seems to me that it is on the wrong side of the date line.
> Does someone know what the correct value is?
> 
>                   - Tom
> 
> 

+----------------------+---+
| Ross Johnson         |   | E-Mail: rpj@ise.canberra.edu.au
| Info Sciences and Eng|___|
| University of Canberra   | FAX:    +61 6 2015227
| PO Box 1                 |
| Belconnen  ACT    2616   | WWW:    http://willow.canberra.edu.au/~rpj/
| AUSTRALIA                |
+--------------------------+



Fri, 15 Jan 1999 17:39:17 +1100 (EST)
Ross Johnson <rpj@ise.canberra.edu.au>
Re: [HACKERS] Time zones
Ross Johnson <rpj@ise.canberra.edu.au> writes:
> Australian Eastern Std Time is GMT-10.

GMT+10, surely, unless the sun started rising in the west
when I wasn't looking.  Hawaii is in the right place to
be GMT-10 ... maybe that's the source of the confusion?

>> 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.

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 ...

			regards, tom lane

Fri, 15 Jan 1999 02:10:21 -0500
Tom Lane <tgl@sss.pgh.pa.us>
Re: [HACKERS] Time zones 
Tom Lane <tgl@sss.pgh.pa.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"

15 Jan 1999 09:31:18 +0100
Tom Ivar Helbekkmo <tih@nhh.no>
Re: [HACKERS] Time zones
On Fri, 15 Jan 1999, Tom Lane wrote:

> Ross Johnson <rpj@ise.canberra.edu.au> writes:
> > Australian Eastern Std Time is GMT-10.
> 
> GMT+10, surely, unless the sun started rising in the west
> when I wasn't looking.  Hawaii is in the right place to
> be GMT-10 ... maybe that's the source of the confusion?

Yes. Sorry. Glad I was able to illustrate the confusion for everyone
:-)

+----------------------+---+
| Ross Johnson         |   | E-Mail: rpj@ise.canberra.edu.au
| Info Sciences and Eng|___|
| University of Canberra   | FAX:    +61 6 2015227
| PO Box 1                 |
| Belconnen  ACT    2616   | WWW:    http://willow.canberra.edu.au/~rpj/
| AUSTRALIA                |
+--------------------------+



Fri, 15 Jan 1999 22:28:38 +1100 (EST)
Ross Johnson <rpj@ise.canberra.edu.au>
Re: [HACKERS] Time zones 
> > Hawaii is in the right place to
> > be GMT-10 ... maybe that's the source of the confusion?

Great. I'll assume it was a sign flip, and fix it unless I hear
otherwise.

Thanks.

                   - Tom

Fri, 15 Jan 1999 14:52:57 +0000
"Thomas G. Lockhart" <lockhart@alumni.caltech.edu>
Re: [HACKERS] Time zones