Cross zone alarm

What exactly is a cross zone alarm? And how can it be enabled on the 2 gig panel ?

Cross zoning means two sensor/zones must activate within the time out period (Q34) selectable for 10-120 seconds) in order for panel to go into alarm for the sensors that are crossed.

The individual crossed sensor zone will never alarm panel unless the other crossed sensor zone also is activated (and then only if the two sensors are activated within the time set)

The two sensors must be installed as zone 47 and 48, and cross zoning must be enabled (Q31(1)