If the point’s out slot is linked to the input of a math component (an Average object, for example) or to the priority array input of a writable control point, a value of nan causes the calculation to return an invalid result. The null value, however, causes the calculation to ignore the erroneous input. In the linked Average example, the result reflects the average of the other non-null input values, instead of displaying nan. The linked writable point drops down to the next-highest priority arrayed input (or fallback) for control, instead of displaying nan.

For numeric points, the driver provides these facets:

For enum points: Key: isNull - Type: Integer - if the specified value is present, the driver returns a null value.