GDS Alerts - Advice of Schedule Change (ASC)
ASC messages (UN/TK) can now be sent for GDS bookings (once confirmed in ameliaRES) if a flight has been cancelled or modified. This option is available from the Alerts form for individual or ALL affected reservations.
A UN message is sent for a cancelled or renamed flight, while TK indicates a passenger's new flight after re-accomodation (Bulk Move), or from changes to either the departure or arrival time of a flight.
Figure: Alerts form - Send ASC button