Mode S information
It depends on the automation system being used by the controller. The information available in mode S downlink includes IAS, HEADING,CALLSIGN, FMS ID, AIRFRAME ADDRESS, ALTITUDE. Most modern systems show all these to the controllers. However to avoid clutter on the screens and to aid brevity the system administrators may choose to display only a few of these. Nevertheles access to view these is available albeit indirectly.