Re: [POLL] Proposed syntax for timestamps with time zone info (was: [FEATURE REQUEST] Timezone support in org-mode datestamps and org-agenda)

[ypuntot]

For the Poll, the Jeans proposal would be to introduce manually:
[2024-02-04 12:00 @America/Vancouver]
And org to convert it into:
[2024-02-04 12:00 @-08,America/Vancouver]
?

Ihor's would add the option to get warnings, in case tzdata changes, when that 
timestamp is generated?
[2024-02-04 12:00 @-08,!America/Vancouver]
?

Feb 5, 2023 13:12:25 Jean Louis <bugs@gnu.support>:

> * Ihor Radchenko <yantar92@posteo.net> [2023-02-05 13:45]:
>> [2024-02-04 12:00 @-08,America/Vancouver] will use fixed -8 offset
> 
> What does that mean practically? Provide example for better
> understanding.
> 
> - The UTC offset is not certain to remain fixed in the future.
> 
> - If you do not have the time of creation of the timestamp above, you
>   cannot know with certainty what was the offset in past, to calculate
>   new UTC offset in case it changed
> 
> - As not even time zone is certain to remain in existence in future,
>   you will need to use time zone, in order to derive that future UTC
>   offset correctly. As it could change in mean time.
> 
> What is meaning of "fixed -8 offset"?
> 
>> [2024-02-04 12:00 @-08] will also use fixed -8 offset
> 
> That type of timestamp does not clearly show the time zone, that one
> may only be understood as timestamp with UTC offset. UTC time may be
> derived from such timestamp. That offset should remain fixed, as there
> is no time zone associated. It is UTC time represented with offset.
> 
>> [2024-02-04 12:00 @America/Vancouver] will use @America/Vancouver time
>> zone, as it is be defined in you OS time zone database.
> 
> If you do not keep UTC offset, you will miss changes in future and
> generate errors.
> 
>> [2024-02-04 12:00 @-08,!America/Vancouver] (note "!") will use fixed -8
>> offset, but also calculate America/Vancouver time from TZ database,
>> compare it with the time coming from -8 offset, and warn you if there is
>> inconsistency.
> 
> The UTC offset is the log what was the UTC offset at the time point
> when timestamp was created, as future UTC offset cannot be known.
> 
> Making it "fixed" does not fix it in real time, you are then
> introducing something new than what other programs do with time.
> 
> I do not think that you need "!", you are creating work not necessary
> for users.
> 
> If users wish to get some warnings, let them customize single option.
> 
> Not timestamp by timestamp.
> 
> --
> Jean
> 
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