Do .ics calendar invitations always copy the event, rather than link?

Question

It's possible to create an .ics file attachment in an email or an instant message, usually representing a Calendar invitation to an event. For instance, in my Calendar app on my phone, if I click "share", I have the option "Share as calendar file (ICS)". I can then send this file to other people.

Once I have shared this .ics file, and someone imports the event, is that event copied, or is it simply referenced to the event in my calendar? If it's just a copy, then I would expect changes to the event in my calendar not to propagate to anyone who had imported the event, since the event is merely a copy. However, if it is a link or a reference, then I would expect changes to automatically propagate to anyone that I had shared the event with. For example, in Google Calendar's interface, if I add someone's Google account to the guest list of an event, any changes to the event get automatically shared with that guest. Does the same apply to .ics files?

Does an .ics file guarantee a copy, rather than an always synced reference?

Answer 1

The .ics file contains a full copy of the event. (It is in iCalendar format, which is more or less just a text file which you can open in Notepad and take a look for yourself.)

It may have vendor-specific data such as reference URLs, so that sharing events between users of the same calendar app could potentially create a live-updating link, but that is not the main mode of operation, and will almost never happen when sharing ICS files between different software.

Answer 2

An .ics file guarantees a copy and nothing else. The total data from your calendar is stored into the file you create and when imported is copied into the receiver's calendar program.

Both copies are on different computers and are completely independent. Any changes you do is done on your computer, any change the receiver does to your event is local to his. No computer can access the other (and doesn't try even if it can).

For example, I many times change the title of the received event to suit me, rather than leave the original.