[tz] Tzdb and the Sunshine Protection Act

[Paul Gilmartin]

On 3/2/23 15:44:49, Paul Eggert via tz wrote:

> On 3/2/23 14:22, Brooks Harris via tz wrote:
>> How will tzdb manage this?
>     ...
> My biggest worry is the set of backward compatibility zones EST5EDT, CST6CDT, MST7MDT, PST8PDT as their continued use would lead to so much confusion that they'd be more trouble than they're worth. Presumably we would retire them by moving them to "backzone". "EST" and "MST" might need to retire as well. (Luckily, there is no "CST" or "PST".)

The forms containing numbers are mandated by POSIX:

<https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08>
     ...
The expanded format (for all TZ s whose value does not have a <colon> as the first character) is as follows:

stdoffset[dst[offset][,start[/time],end[/time]]]

and are the only forms supported by IBM's flagship operating system, z/OS:
<https://www.ibm.com/docs/en/zos/2.5.0?topic=variable-command-format>.

In the long term the change will prove pointless.  People will
readjust their hours of activity to match the hours of daylight
as happened when clocks were advanced 6 hours in the  past 4 centuries:
<https://www.bible.com/bible/1/MAT.20.1-16.KJV>, then clamor for another
adjustment.

-- 
gil