Chrysler Dodge Caravan 2007 Owner's Manual page 170

170 UNDERSTANDING THE FEATURES OF YOUR VEHICLE
Compass Variance
Compass Variance is the difference between magnetic
North and Geographic North. In some areas of the
country, the difference between magnetic and geographic
North is great enough to cause the compass to give false
readings. If this occurs, the compass variance must be set.
NOTE: Magnetic materials should be kept away from
the overhead console.