Use this dialog to calculate the Overage Amount field in the Overages table.
Fields with colored backgrounds are recalculated each time the Calculate button is clicked or any field is edited (if "Auto-calculate" is selected) unless you lock them by clicking the Lock icon.
Calculated as the sum of the Overage column in the table. Click the unlock icon to directly edit the field and then click the icon again to lock that value. The value in this field is copied into the Overage Amount field in the Overages table when the Save & Exit button is clicked.