A unit type can also be specified to do spying automatically. The outcome of spying is calculated once/unit/turn, at the beginning of the turn (after move calculation but before any players can do anything). Spying can happen to any unit not on the spying unit's side.
UnitTypeProperty: spy-chance .01n%
This property is the chance that the unit's spies will find out something.
Defaults to 0.
UnitTypeProperty: spy-range dist
This property is the maximum distance at which the unit's spies will find out
something.
Defaults to 0.
Table: spy-quality u1 u2 -> n%
This table gives the chance that u1's spies will return information
about a unit of type u2.
Defaults to 100.