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

[Thomas S. Dye]

Aloha Jean Louis,

Jean Louis <bugs@gnu.support> writes:

> * Thomas S. Dye <tsd@tsdye.online> [2023-01-19 19:23]:
> > Only occurrences require absolute time, UTC.  Events do not. 
> > They
> > follow the user's space/time.
>
> I understand you got your context specific terminology, from the
> mentioned book, where you are making philosophically different
> distinction between occurence and event as opposed to 
> distinction by
> its ordinary meaning in English.
Ordinary meanings are often polysemous, so context is important. 
A big part of philosophy is limiting the confusion caused by 
polysemy. Ramsey was specifically concerned to distinguish two 
senses of the word event because he was certain that using event 
with this polysemy would sow confusion.   

> What really matters
> -------------------
>
> What matters is aid to users' life.
>
> When arguing, try to make a checklist and TEST it:
>
> - [ ] can user easily understand the time displayed?
>
> - [ ] can user relate the displayed time to his local time 
> without
>   hesitation?
>
> - [ ] is that program that programmer creates beneficial to user 
> or to
>   programmer, or theoretician of absolutes, rights and wrongs?
>
> How to test it?
>
> Usability Testing 101:
> https://www.nngroup.com/articles/usability-testing-101/
I'm hopeful that Ramsey's distinction between event and occurrence 
contributes to what really matters.  How that distinction is 
communicated to the user most effectively is an open question, 
IMO.

> Today there is in computing pretty much agreement that:
> -------------------------------------------------------
>
> - All computer time should be stored to UTC, UTC being basis for 
> any
>   other computations
>
> - System libraries have (or should have) various configurations
>
> - Computer users should be shown their local time
I was thinking that Org timestamps should record the information 
needed to let Org calculate user's local time so it is synchronous 
with other users' local times. This ought to make it possible to 
take into account unforeseen, arbitrary changes in timezone (as 
when a legislative body imposes or rescinds DST) that take place 
between the time an event is scheduled and when it takes place. 
Using absolute time (UTC) stored before the arbitrary change in 
timezone will cause problems.  Of course, arbitrary changes in 
timezone do not affect an occurrence, so storing UTC in this 
instance is correct.

> * Overview of noun occurrence
> -----------------------------
>
>
> The noun occurrence has 2 senses (first 2 from tagged texts)
> 1. (29) happening, occurrence, occurrent, natural event -- (an 
> event that happens)
> 2. (3) occurrence -- (an instance of something occurring; "a 
> disease of frequent occurrence"; "the occurrence (or presence) 
> of life on other planets")
>
> * Overview of noun event
>
> The noun event has 4 senses (first 2 from tagged texts)
> 1. (62) event -- (something that happens at a given place and 
> time)
> 2. (6) event, case -- (a special set of circumstances; "in that 
> event, the first possibility is excluded"; "it may rain in which 
> case the picnic will be canceled")
> 3. event -- (a phenomenon located at a single point in 
> space-time; the fundamental observational entity in relativity 
> theory)
> 4. consequence, effect, outcome, result, event, issue, upshot -- 
> (a phenomenon
> that follows and is caused by some previous phenomenon; "the 
> magnetic effect was
> greater when the rod was lengthwise"; "his decision had 
> depressing consequences
> for business"; "he acted very wise after the event")

Yes, you can see all the polysemy.  Also, you can see why Ramsey 
was happy with event, and less so with occurrence.  The important 
point is the distinction he proposed, not the words used to 
express it.  I think the distinction is germane to understanding 
what information is needed to let Org calculate user's local time 
so it is synchronous with other users' local times.  To my mind, 
it helps bring order out of complexity.

All the best,
Tom
--
Thomas S. Dye
https://tsdye.online/tsdye