[tz] Java & Rearguard

Paul Eggert eggert at cs.ucla.edu
Sat Jun 1 07:05:41 UTC 2019

Brian Inglis wrote:
> The query is what does the (CLDR/ICU) label apply to: the offset or the time
> period?
> The label would seem to apply to the period of Location Summer Time, Location
> Winter Time, Location Daylight Saving Time, Location Standard Time, rather than
> denoting the time zone offset.
> So what then should you label the extra periods: use the same labels as the
> previous uses of the same offsets, or give the extra periods their own unique
> labels, and what should those unique labels indicate?

I'm afraid I'm having trouble connecting your question to the CLDR tables, 
because I don't understand how CLDR works in detail. Looking at 
<https://unicode.org/cldr/charts/latest/by_type/> it appears that CLDR doesn't 
key on the string "Africa/Casablanca" when trying to generate labels for time 
zones. Instead, it keys on strings like "Africa Western" (I don't know where 
these strings come from; they were never in tzdb) and translates these keys to 
strings like "heure d’Afrique de l’Ouest" (French). The list of such keys for 
African time zones is:

Africa Central
Africa Eastern
Africa Southern
Africa Western
Cape Verde
French Southern
Indian Ocean

These mostly appear to reflect abbreviations that were formerly in tzdb (e.g., 
MUT for "Mauritius Time") but were removed from tzdb in 2017 on the grounds that 
tzdb should reflect existing practice instead of imposing its own invented 
abbreviations. Evidently CLDR has more of a packrat mentality, and does not 
remove such entries even if the upstream source (tzdb in this case) no longer 
uses them even indirectly. And it's not clear to me how a program would 
automatically map Africa/Casablanca's "+01" and "+02" to "Africa Western" and 
"Morocco Ramadan" (or whatever).

The whole thing is a bit of a mess, I'm afraid. I'm not sure we'd be doing CLDR 
favors by inventing names like "Morocco Ramadan Time", as this would merely give 
translators more make-work that in practice would be useless or confusing or both.

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