[tz] Unfortunate time zone names in the United States
eggert at cs.ucla.edu
Thu Mar 17 23:14:52 UTC 2022
On 3/17/22 14:31, Chris Walton via tz wrote:
> Yukon recently did the same thing.
When Yukon did that, we modeled that as America/Whitehorse and
America/Dawson being on -07 standard time all year, with the
abbreviation "MST". This made sense, as that's what "MST" means
elsewhere in North America.
This new change, if it becomes law, won't be so easy to deal with. It
will likely cause "Pacific Time" to be synonymous with -07 and "Mountain
Time" to be synonymous with -06 in popular usage, which means that the
entries for America/Whitehorse and America/Dawson will need to change
from "MST" to something else, as "MST" will be misleading.
It's been longstanding tzdb practice to model permanent DST as standard
time. Admittedly this practice has so far been employed only for
locations like Argentina that have fewer users. Still, the precedent is
there and is consistent with the traditional meaning of standard time.
There's another issue here: permanent DST is more likely to break
software applications. For example, permanent DST in California that is
called "PDT" and is 7 hours behind Greenwich would entail a POSIX-style
TZ string like TZ='XXX6PDT7,0/0,J365/23' that means "California's
standard time is 6 hours behind Greenwich, but it springs backward to 7
hours behind Greenwich on January 1 at 00:00 and springs forward on
December 31 at 23:00, so it's actually on daylight saving time all
year". I suspect these oddball TZ strings would break applications, and
I doubt whether this approach would be wise even if it barely conforms
to the standards.
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