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. 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.