Dear all,

as a follow-up to the "Hanoi" thread, I've some questions regarding tzdb policies. As it is a slightly separate / more general point, I'll single that thread out from the initial "Hanoi" discussion.

In particular, I'd like to understand the background of the following item (taken from https://data.iana.org/time-zones/theory.html#naming):

>There should typically be at least one name for each ISO 3166-1 officially
>assigned two-letter code for an inhabited country or territory.

I initially thought this would be the reason for the "Links" of "Asia/Phnom_Penh" and "Asia/Vientiane" to "Asia/Bangkok".

However, latest discussion in the "Hanoi" thread rather attributed these two aliases to backwards compatibility after prior data was moved to the backzone file.

I'd assume the quoted "ISO 3166-1"-based policy could make sense for two reasons:

a) Congruence of ids and decision-making bodies (i.e., countries/governments):

In contrast to data stored using "Asia/Bangkok", systems/data using the "Asia/Phnom_Penh" name/link/alias/id would not need to change/re-configure in case the government of Cambodia decides to deviate from "Asia/Bangkok" at some time

b) Politically:

Even if tzdb names might not be intended as "names", they do surface from time to time, as with configuring time zones on a machine [1], or by applications just passing through tzdb names. I can somehow understand that this is not fully satisfactory in the Vietnam/Hanoi case right now (see below). While it is neither the intention nor the concern of tzdb to deal with this, one can argue that in practice, there is still clearly a practical impact of tzdb names/ids.

So any information on the rationale for the above-quoted rule is appreciated.

Also, I see there are recommendations for implementers regarding localization (e.g., reference to Unicode CLDR), but I could not find recommendations concerning the usage of tzdb names/ids/links/aliases - which, in my understanding, will be the String persisted by most applications in the end?

If so, setting "Vietnamese" data or systems to an "Asia/Bangkok" tzdb identifier would, to some degree, effectively tie that data to Thai legislation. In case Vietnam would deviate from "Asia/Bangkok" in the future (by either Thai or Vietnamese decision), legacy data might need to be change to an "Asia/Hanoi" identifier. I'd be interested in pointers if this aspect was ever discussed here or is considered relevant at all.

Thanks and best,
Hans-Joerg

ps.: as for the Vietnam case, note that the "displayName()" property in Java shows "Indochina" for most zones under discussion [2]

Also Unicode CLDR translations look tricky in this case (http://st.unicode.org/cldr-apps/survey?_=en&x=r_zones)

[1] E.g. https://askubuntu.com/questions/323131/setting-timezone-from-terminal/323163 points out the two options of

sudo cp /usr/share/zoneinfo/Asia/Bangkok /etc/localtime

(explicit!)

tzselect

..yielding the following dialogue:

Please select a country whose clocks agree with yours.
1) Afghanistan        18) Israel            35) Palestine
.........
15) Indonesia        32) Nepal            49) Vietnam
16) Iran        33) Oman            50) Yemen
17) Iraq        34) Pakistan
#? 49

Please select one of the following time zone regions.
1) Indochina (most areas)
2) Vietnam (south)

...which looks better, but is also not ideal from a user point-of-view...

[2] Java TimeZone.getDisplayName() output for EN/DE/FR locale (Oracle JDK 1.8.0_191):

Asia/Bangkok / Indochina Time
Asia/Bangkok / Indochina Zeit
Asia/Bangkok / Heure d'Indochine
Asia/Ho_Chi_Minh / Indochina Time
Asia/Ho_Chi_Minh / Indochina Zeit
Asia/Ho_Chi_Minh / Heure d'Indochine
Asia/Phnom_Penh / Indochina Time
Asia/Phnom_Penh / Indochina Zeit
Asia/Phnom_Penh / Heure d'Indochine
Asia/Saigon / Indochina Time
Asia/Saigon / Indochina Zeit
Asia/Saigon / Heure d'Indochine
Asia/Vientiane / Indochina Time
Asia/Vientiane / Indochina Zeit
Asia/Vientiane / Heure d'Indochine
VST / Indochina Time
VST / Indochina Zeit
VST / Heure d'Indochine

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