FW: timezones offset from what?

Paul Eggert eggert at CS.UCLA.EDU
Mon May 22 19:35:36 UTC 2006

"Olson, Arthur David \(NIH/NCI\) [E]" <olsona at dc37a.nci.nih.gov> writes:

> From: Zefram [mailto:zefram at fysh.org] 
> Sent: Friday, May 19, 2006 12:30 PM

> there's no rigorous
> treatment of what base time scale to apply the offset to.

In the current implementation, the base time scale is always UTC,
usually with leap seconds skipped, but leap second support is there if
you want it.  Hence UK times are de facto (modulo leap seconds), not
de jure.

I suppose there might be more-advanced applications where most Unix
processes wants to use a UTC-based time scale, but one process wants
to use a GMT-based one (or UT1, or Mars solar time, etc.).  But that
sounds pretty specialized.  It shouldn't be needed for civil times
anywhere on the planet, so it'd probably be an astronomical
application or something like that.  If someone wanted to do that, I'd
like to see their implementation before worrying about adding support
for it to the tz code or database.

There's a similar issue for support for other calendars, e.g., the
Persian calendar in widespread use in Iran.

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