From Honeywell FMS Pilot Guide:
The Predictive GPS page displays information about GPS integrity and availablility at the ETA(and for intervals before and after) for the destination and an entered waypoint.
Y (yes) or N (no) is displayed below the ETA and + or - time intervals in line 2 to indicate whether GPS is predicted to be available as primary means of navigation at the destination.
The pilot can enter a waypoint in 3L for the system to run predictions at that waypoint. After a waypoint is entered in 3L, boxes are displayed in 3R to enter the ETA for that waypoint.
Hope it helps!
G