[Retitling from "Single source of truth for timezone data" as per <https://data.iana.org/time-zones/theory.html#accuracy>.] On 2022-12-02 22:57, Guy Harris via tz wrote:
So we could, in principle:
have new versions of the source files with an additional METAZONE field at the end of Zone lines;
have zic handle that field;
have a tool to strip off the METAZONE field, to produce files to be handled by tools that read source files and that*don't* understand the METAZONE field;
Good suggestion. Possibly even better would be leave the current files alone (this would cause less disruption downstream), and have a new file containing a table that maps abbreviations+contexts to longer names that disambiguate the abbreviations. These longer names could then be used by CLDR and any other localization efforts. Something like this, say: ACST * Australian Central Standard ACDT * Australian Central Daylight AST * Atlantic Standard ADT * Atlantic Daylight APT * Atlantic Peace AWT * Atlantic War ADDT * Atlantic Double Daylight ... CST America/* Central Standard CST Asia/* China Standard ... IST Asia/Jerusalem Israel Standard IST Asia/Kolkata India Standard IST Europe/Dublin Irish Standard ... BMT Asia/Jakarta Batavia Mean BMT Europe/Zurich Bern Mean BMT America/Barbados Bridgetown Mean BMT Europe/Chisinau Bucharest Mean where the xMT abbreviation list is shortened by omitting entries like the following as they can be deduced automatically: BMT Asia/Baghdad Baghdad Mean BMT Asia/Bangkok Bangkok Mean BMT America/Bermuda Bermuda Mean BMT America/Bogota Bogota Mean BMT Europe/Brussels Brussels Mean BMT Europe/Bucharest Bucharest Mean and with the convention that LMT always denotes local mean time when it appears in a Zone line (as opposed to a continuation line). This new table would be a machine-processable improvement on the less-formal abbreviation lists that are already published here: https://data.iana.org/time-zones/theory.html#abbreviations Such a table should be relatively easy to maintain, as the set of abbreviations is small and rarely changes now that we've removed invented abbreviations. Of course it would require some work from the CLDR side, if they want to use this new table instead of doing things their current way, so it'd be nice to hear from the CLDR side before proceeding.