On 2024-12-12 23:48, Guy Harris via tz wrote:
On Dec 12, 2024, at 8:46 AM, Brian Park via tz wrote:
One thing rarely mentioned in these discussions is the millions of electronic
devices (e.g. timers, clocks, watches, thermostats, etc) which are hardcoded to
handle DST using the current US/Canada rules (i.e. first Sunday in Nov, second
Sunday in Mar). If the DST rules are changed, those devices will become
obsolete because the firmware for those things will never be updated.
So do they sell special models in Arizona (along with the regular model, for
residents of the Navajo Nation)?
Or do they have, for example, a switch that controls whether to observe DST or
not?
Most of them seem to, but unless they receive and use an RC DST flag rather than
rules, they will not switch at the right time, as in 2007:
$ zdump -Vc2007,2008 Navajo
Navajo Sun Mar 11 08:59:59 2007 UT = Sun Mar 11 01:59:59 2007 MST isdst=0
gmtoff=-25200
Navajo Sun Mar 11 09:00:00 2007 UT = Sun Mar 11 03:00:00 2007 MDT isdst=1
gmtoff=-21600
Navajo Sun Nov 4 07:59:59 2007 UT = Sun Nov 4 01:59:59 2007 MDT isdst=1
gmtoff=-21600
Navajo Sun Nov 4 08:00:00 2007 UT = Sun Nov 4 01:00:00 2007 MST isdst=0
gmtoff=-25200
--
Take care. Thanks, Brian Inglis Calgary, Alberta, Canada
La perfection est atteinte Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut
-- Antoine de Saint-Exupéry
