On 2026-09-29 15:39, Robert Elz via tz wrote:
Consider for a minute what would happen should the US State Dept demand (or US Congress, or the California legislature) decide that California will also use UTC-7 year round, and legislate that the abbreviation shall be CAT (CA Time).
Even more, consider what would happen if every state and province, or indeed every city, legislated its own time zone abbreviation and insisted that we use it. What would we do then?
What we'd likely do is switch to numeric abbreviations. There are good reasons in TZDB itself to avoid a multiplicity of alphabetic abbreviations for what is in practice the same timekeeping. And this isn't just us: there's a similar issue, for example, for Canadian national broadcasts, which will almost surely not list PCT, YST, WNUT, NWTT, ABT, CST, MBT, EST separately, as these would be eight confusing abbreviations for what are only three distinct time zones.
Until/unless popular usage agrees on time zone abbreviations, numeric abbreviations are likely the best way to go. Besides, abbreviation choice is more of a localization than a timekeeping issue, and it's better for CLDR (which deals with localization) to deal with it than for us to deal with it.
CLDR doesn't really impact enough places to make a huge difference
Although that was true decades ago, nowadays surely many more users deal with time zone names and abbreviations via CLDR than directly via TZDB.
