Difference between iCalendar (.ics) and the vCalendar (.vcs)

Question

I want to send booking information through mail in an attachment to add in MS Outlook. Which format is better? Especially for MS Outlook 2003?

Answer 1

Both .ics and .vcs files are in ASCII. If you use "Save As" option to save a calendar entry (Appt, Meeting Request/Response/Postpone/Cancel and etc) in both .ics and .vcs format and use vimdiff, you can easily see the difference.

Both .vcs (vCal) and .ics (iCal) belongs to the same VCALENDAR camp, but .vcs file shows "VERSION:1.0" whereas .ics file uses "VERSION:2.0".

The spec for vCalendar v1.0 can be found at http://www.imc.org/pdi/pdiproddev.html. The spec for iCalendar (vCalendar v2.0) is in RFC5545. In general, the newer is better, and that is true for Outlook 2007 and onward, but not for Outlook 2003.

For Outlook 2003, the behavior is peculiar. It can save the same calendar entry in both .ics and .vcs format, but it only read & display .vcs file correctly. It can read .ics file but it omits some fields and does not display it in calendar mode. My guess is that back then Microsoft wanted to provide .ics to be compatible with Mac's iCal but not quite committed to v2.0 yet.

So I would say for Outlook 2003, .vcs is the native format.