On Wed, Feb 01, 2023 at 10:06:15AM +0100, Stefan Nobis wrote:
> <tomas@tuxteam.de> writes:
> 
> > 2023-03-23 02:30 @Europe/Berlin refers to /two/ points in time, thus
> > it /is/ ambiguous.
> 
> As far as I understand the definitions, the point in time "2023-03-23
> 02:30 @Europe/Berlin" is clearly defined as 2023-03-23 02:30 UTC+0100.
> 
> A bit more problematic would be "2023-03-26 02:30 @Europe/Berlin".

[...]

This has already been cleared in the thread: I got the year the
wrong way around.

> The real problem would be e.g. "2023-10-29 02:30 @Europe/Berlin". This
> point in time really exist twice, there is 02A:30 (02:30 UTC+0200) and
> 02B:30 (02:30 UTC+0100) in this night of switching back from DST to
> normal time!
> 
> So, in general, only using the time zone name may indeed lead to
> ambiguous interpretations of timestamps.

...which stems from the fact that the very concept of "time zone"
is somewhat ambiguous, too. Some time zone designations carry the
fact of whether they are supposed to be summer times or not with
them (as with CET/CEST), some not (as above). The time zone database
is only known for a limited time into future and may change with
political vagaries. Yadda, yadda.

If you really want to have fun with this (and this thread hasn't
satisfied your thirst ;-) see [1].

Cheers

[1] https://en.wikipedia.org/wiki/British_Summer_Time#Early_history
-- 
t