If specified, the OnClientAppointmentSerialized client-side event handler allows you to populate appointments with custom data before sending them to the Web Service. In the case of server-side binding, the event will not be raised.
Two parameters are passed to the handler:
sender - the scheduler client object;
eventArgs with two properties:
get_appointment() - the appointment that is about to be updated.
set_data() - the appointment data such as Subject, Start and End properties.
This event cannot be cancelled.