Calendar changes time zone for incoming event.

Question

Calendar changes time zone for incoming event.

Whenever I receive a meeting invite from Dubai, the time zone is changed by 1 hour when it gets added to my Calendar.

The incoming invite from Teams looks like this when opened with a text editor:

BEGIN:VCALENDAR

METHOD:REQUEST

PRODID:Microsoft Exchange Server 2010

VERSION:2.0

BEGIN:VTIMEZONE

TZID:Arabian Standard Time

BEGIN:STANDARD

DTSTART:16010101T000000

TZOFFSETFROM:+0400

TZOFFSETTO:+0400

END:STANDARD

BEGIN:DAYLIGHT

DTSTART:16010101T000000

TZOFFSETFROM:+0400

TZOFFSETTO:+0400

END:DAYLIGHT

END:VTIMEZONE

BEGIN:VEVENT

However when I accept it and it is added to my calendar, the accept reply looks like this:

BEGIN:VCALENDAR

CALSCALE:GREGORIAN

VERSION:2.0

METHOD:REPLY

PRODID:-//Apple Inc.//macOS 11.2.3//EN

BEGIN:VTIMEZONE

TZID:Asia/Aden

BEGIN:STANDARD

TZOFFSETFROM:+1852

DTSTART:19470314T000008

TZNAME:GMT+3

TZOFFSETTO:+0300

RDATE:19470314T000008

END:STANDARD

END:VTIMEZONE

BEGIN:VEVENT

Therefor it now shows an hour later in my local (Thailand) calendar.

This happens every time I receive an event that is sent from anybody in the UAE

iMac Line (2012 and Later)

Posted on Mar 29, 2021 5:43 PM

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Answer 1

Apr 1, 2021 5:34 PM in response to Pieter Boshoff

There is no Arabian Standard Time setting in iOS/MacOS which is why the time zone ID is changing and since there is no location information in the invitation, it just picks the first appropriate ID in the BSD list which is Asia/Aden. This is not the cause of the problem.

I would say that the cause is the way in which the Exchange server is creating the invitation (whether it is a problem with Exchange or server or user settings I have no idea). Arabian Standard Time is UTC+3, the UTC+4 setting in the invitation is because the UAE is on daylight saving time which is Arabian Daylight Time. I'd say that the "Standard" in the name and the BEGIN and END settings being "STANDARD" is wrong and is overriding the "daylight" setting further down in the ICS file.

You say invitations from Dubai always have this problem, but is it really every one, or just when they are on daylight saving?

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Answer 2

Apr 1, 2021 5:52 PM in response to gakushaburu

So basically there is no agreed standard - typical of the industry - can't agree on anything.

Thanks for the reply anyway.

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Calendar changes time zone for incoming event.

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