Question

I am having a form for scheduling a meeting request. and now i need to add timezones to it.

I have two dropdowns one for timezone and one for time. so if i select timezone as (GMT-11:00) Midway Island, Samoa and time as 4:00 PM than a mail goes to one person with the meeting request in his outlook.

now his outlook is configured with IST but as the timezone seleceted is new timezone so it should be adjusted appropriatedly.

$ical =    'BEGIN:VCALENDAR
PRODID:-//Microsoft Corporation//Outlook 11.0 MIMEDIR//EN
VERSION:2.0
METHOD:REQUEST
BEGIN:VEVENT
ORGANIZER:MAILTO:'.$from_address.'
ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=TRUE;
 CN='.$to.':mailto:'.$to.'
DTSTART:'.$dtstart.'
DTEND:'.$dtend.'
LOCATION:'.$meeting_location.'
TRANSP:OPAQUE
SEQUENCE:0
UID:'.$cal_uid.'
DTSTAMP:'.$todaystamp.'
DESCRIPTION:'.$meeting_description.'
SUMMARY:'.$subject.'
PRIORITY:5
CLASS:PUBLIC
END:VEVENT
END:VCALENDAR';

i have searched on it.. and it says that i have to add VTIMEZONE, TZID, TZOFFSETFROM, TZOFFSETTO
now i am not getting the meaning of TZOFFSETFROM, TZOFFSETTO…? and how to use these to execute the task

Answer 1

Note that whatever TZID you pick (they’re free format), they should have a matching entry in the VTIMEZONE section of the configuration. Contrary to what @anmari said, the VTIMEZONE section is required for the calendar event to be recognized by Outlook etc (showing accept/decline buttons).

In my experience, the smartest approach is to take (copy/paste from mail source) an existing VTIMEZONE configuration. This is the one for Western Europe, for example:

BEGIN:VTIMEZONE
TZID:W. Europe Standard Time
BEGIN:STANDARD
DTSTART:16010101T030000
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=10
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:16010101T020000
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=3
END:DAYLIGHT
END:VTIMEZONE

Don’t change anything – just copy/paste this into your email code. Now, internally we use a PHP time zone matching this one, for instance “Europe/Amsterdam”. We use this as a base time zone, and convert the VEVENT‘s values to it using PHP’s DateTime class.

$Date = new DateTime( $event_date ); // this will be in the server's time zone

// convert it to the 'internal' time zone
$Date->setTimezone( new DateTimeZone( 'Europe/Amsterdam' ) );

// ...

echo "BEGIN:VEVENT\n";
echo "DTSTART;TZID=W. Europe Standard Time:" . $Date->format( 'Ymd\THis' ) . "\n"

When sending this out, the receiving calendar/email client will automatically convert the incoming time data to the recipient’s time zone. Yay! 🙂