At first: Sorry for my bad english!

i have a Question regarding Zimbra 7 Web-Client / Calendar.

Ive created a calender with the admin account, set myself as administrator and sent invitations to my co workers (read only)

The Calender is called "Mr. XX's Appointments" for example.

What i want to do is:

i want to add a appointment like ,,visit at the doctors office" for example.

then i want to add some information like ,,Blood taking at Dr. XXX" but i dont want my co workers to see where i am and what ive got to do cause its private. I just want them to see that im not in the office at this time.

Is it possible to do it?