Re: Two problems with export to Google calendar

[Max Nikulin <manikulin@gmail.com>]

On 07/12/2022 19:56, Ihor Radchenko wrote:
> Neil Jerram:
> 
>> X-WR-TIMEZONE:BST
>>
>> which I think was intended to mean British Summer Time; but Google
>> interpreted it as Bangladesh Standard Time.  As a result, my events
>> from Org are shown at the wrong time in Google calendar.
> 
> By default, ox-icalendar takes the value of your TZ environment variable.

I think, in most cases TZ is not set, so (format-time-string "%Z") is 
used to get abbreviation (that is ambiguous).

On Linux we may try

     timedatectl show --property=Timezone --value

during generation of export template. There is a chance that init system 
is not systemd, so the command is not available. It is possible to get 
timezone from /etc/timezone, but the code would not concise since it may 
be a text file or a symlink to the definition. I have no idea concerning 
macOS or Windows.

Emacs relies on libc to handle time zones, and there is no API to get 
the identifier. I miss the option available in modern browser JavaScript

     new Intl.DateTimeFormat().resolvedOptions().timeZone

I have never read .ics file spec, so I am unaware what kinds of name are 
allowed for X-WR-TIMEZONE.