[Users] [Bug 4418] New: add local/"floating" TZ support for time events which do not contain TZID

[Pierre Fortin]

On Sat, 5 Dec 2020 21:04:47 +0100 Michael Rasmussen via Users wrote:

>On Sat, 5 Dec 2020 21:19:20 +0200
>Paul Steyn <paulsteyn1 at afrihost.co.za> wrote:
>
>> 
>> As far as I can tell, this is wrong for "floating" times, which, as I
>> understand it, should just display the time as given, as if it were in
>> your local timezone.
>>   
>You are interpretation is more or less correct. According to the RFC a
>timestamp with out a timezone specification means local timezone. A
>timestamp with timezone Z means the timestamp is specified as UTC time.
>If a specific timezone apart from UTC or local time is required you
>must specify TZID for all timestamps.
>
>See: https://icalendar.org/iCalendar-RFC-5545/3-3-5-date-time.html

Thanks Michael.

So the message I received was of Form#1 (floating[1] time) which should
display as 14:00 to 15:00 regardless of timezone...  The preceding
text/html part of the message displays correctly.

vCalendar appears to be assuming the specified time is UTC (Form#2), thus
incorrectly displaying 09:00 to 10:00 instead of 'floating' 14:00 to
15:00 (UTC would be 19:00 to 20:00)... 

[1] I didn't fully grok 'floating' time when I filed the bug report. This
section of RFC5545 3.3.5 clears it up:
      DATE-TIME values of this type are said to be "floating" and are
      not bound to any time zone in particular.  They are used to
      represent the same hour, minute, and second value regardless of
      which time zone is currently being observed.

Cheers,
Pierre