On 7/19/2026 3:32 AM, Paul Eggert via tz wrote:
On 2026-07-18 13:03, Guy Harris via tz wrote:
And encourage developers to 1) not rely on "EST" in a string meaning
UTC-05 etc., 2) stop using "EST" etc. in time stamp strings and
switch to UTC±N,
Good advice, and it suggests that if the US changes go through as
proposed, TZDB should follow Robert's suggestion[1] and switch North
American time zone abbreviations from the (A|E|C|M|P|AK)(D|S)T
abbreviation family to numeric abbreviations like "-04". This would
help avoid collision with longstanding practice that includes both
standards like Internet RFC 5322 and software packages galore. And
we'd be following our own advice to not generate abbreviations like
"EST".
Perhaps eventually common practice would become clear and we could
start using alphabetic abbreviations again. Until things settle down,
though, numeric abbreviations would likely cause fewer problems than
alphabetic ones.
The suggestion is to use numeric abbreviations such as "-04"? One might
as well set it at %z.
I believe the FORMAT field in the current form has value. My option is
that the FORMAT field should be maintained as a "best effort" name for
how people in that zone refer to their time.
If one wants to get wild we could use USET, USCT, USMT, USPT, USAK,
USHI, USAZ, USPR, USAT (for America/Thule's Atlantic Time). Canada can
have CAEST/CAEDT, CACST/CACDT, CAMST/CAMDT, CAPT ... wherever those
zones end up.
What would break is using America/Puerto_Rico and America/Phoenix in
Canada and expecting the FORMAT to be correct. So we're back to "AST"
and figure out something for America/Thule if the US goes permanent DST.
