Taken from the manual:
“Datalink Target – Target” instructs wingmen to stop their current tasks and attack a target or group of targets nearest to the datalinked target location.
“Datalink Target – Targets” instructs wingmen to stop their current tasks and attack all targets within a 3km radius of the datalinked target location.
“Datalink Target – Target by Type” instructs wingmen to stop their current tasks and attack a target or group of targets of a specified type (SAMs, Vehicles, or Other) nearest to the datalinked target location.
“Datalink Target – Targets by Type” instructs wingmen to stop their current tasks and attack all targets of a specified type (SAMs, Vehicles, or Other) within a 3 km radius of the datalinked target location.
So the wingman will attack targets that are near the datalink target.