[tz] [PATCH] tzdata: Asia/Ha_Noi: Add new timezone

[Trần Ngọc Quân]

On 05/10/2014 07:32, Paul Eggert wrote:
> Tim Parenti wrote:
>
>> ... ICT referring to different UT offsets for several periods. 
>> Perhaps, prior to
>> reunification, NICT and SICT should be used for "North/South
>> Indochina Time"?
>
> It wasn't North vs South.  The new data say that French Indochina
> mostly used UT+7, but sometimes all of French Indochina used UT+8,
> sometimes just South Vietnam, sometimes more of a hodgepodge.  I had
> independently run into this problem and thought of using the
> abbreviation "IDT" (short for InDochina Time) for UT+8 in Indochina to
> help clear this up.
I agree with you.
>
> There's a bigger problem, though.  The new data also tell us that our
> entries for Laos and Cambodia are almost entirely bogus.  We already
> knew that, and I had slated them for 'backzone' anyway, so now's a
> good time to do that.  As a corollary, although we clearly need to fix
> Asia/Ho_Chi_Minh, we don't need a separate Zone for Asia/Hanoi as it
> is identical to Asia/Bangkok since 1970. This will give us a simpler
> fix and an easier-to-maintain result.
>
> A proposed pair of patches is attached.  The first moves the bogus
> data for Cambodia and Laos to 'backzone'.  The second fixes
> Asia/Ho_Chi_Minh and adds a line to zone1970.tab so that users in
> Vietnam now have two choices, one for each half of the country.
>
About second patch:

+Zone Asia/Ho_Chi_Minh	7:06:40 -	LMT	1906 Jul  1
+			7:06:30	-	PLMT	1911 May  1
+			7:00	-	ICT	1942 Dec 31 23:00
+			8:00	-	IDT	1945 Mar 14 23:00
+			9:00	-	JST	1945 Sep  2
+			7:00	-	ICT	1947 Apr  1
+			8:00	-	IDT	1955 Jul  1
+			7:00	-	ICT	1959 Dec 31 23:00
+			8:00	-	IDT	1975 Jun 13
 			7:00	-	ICT

This is Hanoi, not Ho Chi Minh City.

I find an other book about this topic:

Name: Lịch âm dương Việt Nam 1900-2010
Author: Nguyễn Văn Chung
Publisher: Nhà xuất bản văn hóa dân tộc
Edition: 2001

- It confirms the date `1906 Jul 1'. So I think this date is correct.
- It said Phù Liễn is 104°17’17” East. But I think `east of Paris' is
correct. In Google map, it is: 20°47'05.1"N+106°38'22.0"E
Unfortunately, It don't show any other information that we need.

Some photos about Phù Liễn:

* <http://www.panoramio.com/photo/22547402>
* <http://www.panoramio.com/photo/57154621>

-- 
Trần Ngọc Quân.

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