Sharing calendar except for private appointments

How can I share my calendar, but at the same time have private appointments, in such a way that other users cannot see even that I do have these appointments. In other words, everyone can see my office appointments, but no one can see other appointments except for me.
You need to mark those appointments as private when you create them. There is a checkbox on the appointment form to do this.

This was first published in October 2003