Represents the method that handles the MagneticVarianceUpdated event.
[Visual Basic .NET] Public Delegate Sub MagneticVarianceUpdatedEventHandler ( _ ByRef pMagneticVar As esriGpsMagneticVariance _ )
[C#] public delegate void MagneticVarianceUpdatedEventHandler ( ref esriGpsMagneticVariance pMagneticVar );