[tz] Java & Rearguard

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Sat Jun 1 01:52:40 UTC 2019

On 2019-05-31 18:19, Guy Harris wrote:
> On May 31, 2019, at 3:49 PM, Paul Eggert <eggert at cs.ucla.edu> wrote:
>> On the contrary, IEEE Std 1003.1-1998 requires support for so-called "negative DST",
> Can we promote the term "Daylight Shifting Time"?
> 1) Nothing's being "saved", it's just moved from the morning to the evening.
> 2) It can refer either to shifting it from the morning to the evening, as 
> many countries do in the spring, or to shifting it from the evening to the
> morning, as Ireland does in the autumn.
> 3) You don't have to worry about "Saving" vs. "Savings".
> 4) It's still "DST", so you don't have to change, for example, "tm_isdst".

I like the POSIZ TZ env var use of alternative time zone.

Most government decrees say something like we observe standard or true time zone
offset X from effective time until end time then summer or daylight or
alternative time zone offset Y from later effective time until next end time.

In these statements the times and offsets are all independent, depending on
latitude as the times of the seasons change between hemispheres.

A better model for seasonal time changes would just be time zone offsets between
times, ignoring how many transitions per year, or definitions of such as
standard or summer, which should be reduced to just labels for the time zones
during those periods: who really cares or needs to know which is which?

For the current period of Ramadan where some time zones vary, what should the
label be now: the equivalent of Location Ramadan Time, and should the preceding
or following period label be Location Summaer Time?

Each seasonal industry deals with its own seasonal time periods, uncorrelated to
government decrees and astronomical equinoxes, without any difficulties or

Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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