True if the field is included and active in the specified field set. Read/write Boolean.
Remarks
Inactive fields are not visible in the PivotTable list. A field set must have at least one field for which the IsIncluded property is set to True. Attempting to set this property to False for the only field where it is set to True generates a run-time error. This property is ignored when the field set is used on the filter axis. If the user hides the last field in the user interface, the field set is removed from the axis.