It doesn't matter what is the capital, or what the official time zone name happens to be - tz database zone names are derived from the name of the city with the biggest population in an area (often country) that uses the same time. For Vietnam, every reference I can find puts Ho Chi Minh City as being more populated than Ha Noi. Hence Ho_Chi_Minh is the name that is used. It is the same reason that we use Shanghai (not Beijing), and New_York (not Washington). Even if Ha Noi's population should overtake Ho Chi Minh City it would take a long time before we would change the name, now it has been selected - eg: For India we still use Kolkata, even though Mumbai and Delhi seem to have gone (way) past it in population count. Kolkata (when we called it Calcutta) was chosen, and remains... Unless you can show that Ha Noi and Ho Chi Minh City have not used the same local time for some period (a few minutes would be enough) since 1970 an additional zone won't be created for it either. (Differences before 1970 could just possibly be used, sometime in the future, so research into actyal time usage back into history is always useful - if backed by good references.) kre