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

[Tim Cross <theophilusx@gmail.com>]

"Thomas S. Dye" <tsd@tsdye.online> writes:

> Aloha Max,
>
> Max Nikulin <manikulin@gmail.com> writes:
>
>> On 20/01/2023 03:09, Tim Cross wrote:
>>> To reiterate for the last time, there are 2 clear and different use
>>> cases for timestamps associated with meetings.
>>> 1. A meeting timestamp for a meeting where all the participants are in
>>> the same time zone.
>> ...> 2. A meeting timestamp for a meeting where all the participants are in
>>> different time zones....
>>
>> Tim, every scheduled meeting event is associated with some particular time zone,
>> often implicitly. So it is single use case.
>>
>> It is up to participants to negotiate which timezone is the primary one for each
>> event. It is matter of people communication, not technical issue.
>>
>> First Monday 15:00 is (almost) equally precise for
>> - Australia/Canberra having DST
>> - Australia/Darwin where currently no DST
>> - +1000 (the highest chance of improper use unfortunately)
>> - UTC
>>
>> Aside from time transition intervals, it is possible to take any of this variant
>> and to present time local for other participant across the globe.
>>
>> Storage timezone may differ from the current user preference which time zone
>> should be used to display timestamp or to export it.
>>
>> The problem arises when several participants believe that their timezones are
>> primary ones and they do not sync their schedules through a shared file or a DB
>> entry. An application can not solve this problem, but it might try to help to
>> identify it. Some efforts are necessary from user side. Timestamp should contain
>> list of timezones of other participants and cached local time. In such case an
>> application may warn users that local time values become inconsistent due to DST
>> transitions or due to update of time zone database. Unsure to what degree it
>> should be implemented in Org.
>>
>> So
>> - It is participants fault if a meeting is not associated with particular
>>  timezone
>> - Having a fair time handling library, it does not matter what time zone is used
>>  to schedule the meeting.
>
> Or, one can recognize that the meeting is an occurrence that requires absolute time and a
> timestamp with UTC.  Each participant will resolve UTC to the local time where they happen
> to be when the meeting takes place.  The user might toggle between UTC and the local time
> translation using overlays, like pretty entities. This avoids the problem of negotiating a
> timezone caused by forcing an occurrence to be represented as an event relative to a
> fictitious space/time.
>

Exactly.

I am really confused by the constant reference to negotiating between
participants or finding a shared/agreed time zone etc. That is all
totally irrelevant in this use case as outlined. If we were talking
about booking meetings or communicating information about booked
meetings between participants or a different bit of software which
manages sceduling of meetings like one of those many web meeting booking
systems, then that would be a different matter. However, that isn't what
we are talking about. We are talking about org mode. All I am talking
about here is being able to identify two different types of meetings -
ones which need to have times adjusted as a result of daylight savings
time transitions and ones which don't and what mechanism org could use
to distinguish the two. It is that simple. Your occurrence v event
terminology provides two different names which may help label the two
different use cases.

So far, nobody has shown any reason why using UTC to distinguish the
case where the times need to be adjusted and local tz when they don't
won't work a a  mechanism that can be used to allow org to handle things
better than it does now.