Re: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda

[Ihor Radchenko]

Max Nikulin <manikulin@gmail.com> writes:

> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=54764#30
> Re: bug#54764: encode-time: make DST and TIMEZONE fields of the list
> Thu, 14 Apr 2022 15:46:58 -0700
>> If you want to keep the TZDB identifier for advice about how to 
>> interpret dates relative to a timestamp, that's fine. But you should 
>> keep the UT offset in addition to the TZDB identifier, if you want your 
>> app to be fully accurate and useful. For example, you should store 
>> "1950-07-01 00:00:00 +0000 Europe/Lisbon" for a timestamp generated by 
>> TZDB release 2021a, so that when you interpret the timestamp in release 
>> 2021b you'll have an idea of what you're dealing with.
>
> So keeping redundant information may be crucial to get warnings that 
> some timestamps need to be reviewed.

My takeaway from here is that automatically generated timestamps for
past events should better contain redundant information:

"1950-07-01 00:00:00 +0000 Europe/Lisbon"

+0000 is what matters for time calculation while Europe/Lisbon indicates
the actual timezone being implied.

Then, if there is an event of TZ database change, Org might compare
+0000 vs. Europe/Lisbon and display warning if there is discrepancy.

For us, it means that we might potentially reserve 

<1950-07-01 00:00:00+0000@Europe/Lisbon> as a valid timestamp format.
Warning is optional feature we might implement in future.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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