How to distinguish an appointment request from an appointment synchronization?

Hi,
Is there a way to distinguish between an appointment request and an appointment synchronization when receiving an Appointment resource?
If a system receives an appointment resource as an appointment request, it has to notify the participants in order to get the appointment responses. If it receives an appointment resource as an appointment synchronization, it has to store the resource without notifying the participants.
Is there a way to handle that when posting an Appointment resource?