[tz] Permanent DST in the United States

Paul Eggert eggert at cs.ucla.edu
Tue Mar 15 20:00:57 UTC 2022

On 3/15/22 12:05, Jacob Pratt via tz wrote:

> there is no clause that delays implementation, so it looks like it would
> take effect immediately. This could be problematic if the bill becomes law
> near or after the November clock change.

It would be problematic even if it becomes law this month, as it would 
effectively change time zone names and abbreviations immediately. For 
example, the time zone abbreviation in Los Angeles would immediately 
change from "PDT" to "PST" (though the UTC offset would not change).

A *lot* of computer software assumes that timezone abbreviations like 
"PST" have their longstanding meanings. This software was obviously 
misguided, but it's out there and changing it will be quite a hassle. I 
don't envy people who will have the responsibility for cleaning up the 
resulting mess where "PST" has one meaning for older timestamps and a 
different meaning for newer ones and existing standards like Internet 
RFC 5322 continue to say things like "PST is semantically equivalent to 

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