Need to store invisible data (ID) in appointment.

[Jorg]

Hi,
I am creating a delphi database app wich can export appointments in the
database to Outlook (I am using mapi and OLE objects in Delphi).
Everything is working well but now I want to store the AppointmentID from my
database in an appointment in Oulook.
It would be best if this ID is not visible in outlook.

Now I am adding the ID to the subject of an appointment, but that's not an
ideal situation because users can remove it.

I have been looking for invissible properties of an appointment, but I
didn't find any.
Can somebody tell me how to do this?

Thanks in advance
Jorg Borst
(e-mail address removed)