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.