Re: [O] Bug: org-2ft and/or float-time is wrong [9.1.2 (9.1.2-22-ga2a034-elpaplus @ ~/.emacs.d/elpa/org-plus-contrib-20171023/)]

[Allen Li]

On Wed, Nov 1, 2017 at 12:18 AM, Tim Cross <address@hidden> wrote:
>
> My preferences would be
>
> 1. If a timestamp does not include the TZ, then assume the local TZ
> 2. If a timestamp does include the TZ, honour that TZ

Org mode does not support TZ in time strings and adding support isn't
the topic of the current bug.

I want to emphasize the distinction between timestamps and time
strings.  Timestamps are a
float value, Unix timestamps.  Time strings are Org mode specific,
like <2017-10-30 12:34:56>

Timestamps do not have timezone information since they describe an
exact (well, minus leap seconds)
point in time, the number of seconds after the epoch.

> 3. If the timestamp does not include a time component, default to 0:00:0

This is what Org mode does

> for the local TZ

This is what Org mode used to do, now it interprets it as 00:00:00 UTC.

> 4. org-2ft should not enforce the UTC TZ. I agree this is incorrect.
>
> Rationale is that the user should have ability to fully control how
> their timestamps are represented. However, adding the TZ is probably
> just a pain for the majority of use cases, so defaulting to the local
> (wall) TZ is OK provided you can override this consistently by adding
> explicit TZ values.
>
> However, there is some devil in the details we need to work out. For
> example, should we support both TZ names (like AEDT or Australia/Sydney)
> and POSIX style +11/+11:00/+1100, should we add an option to tell org to
> always add TZ info in timestamps which include time components and if
> so, how complex will this need to be e.g. handle setting a future/past
> timestamp which is in a different (daylight savings) offset and what
> about the additional complexity in dealing with timestamp calculations
> where dates might be in different offsets due to daylight savings -
> while all quite possible, it does add significant complexity and this
> may have adverse impact on performance. Not to say we shouldn't do it,
> just that it will take significant work.
>
> I suspect just the first part won't have major impact - at least no more
> than enforcing UTC in org-2ft.

Org mode does not support TZ in time strings currently.  While I would
like such a feature very much,
adding TZ support isn't the topic of the current bug, just fixing how
time strings are interpreted.

>
> Tim
>
> P.S. when you start to think about it, it is easy to see how Java
> screwed up this stuff so badly!