The Invert Exclusion setting allows you to use the elements in the exclusion list as the active ones. This option is used to invert the logic of the exclusion list so the products in the exclusions will be the only products with an active waiting list feature.
If you enable this option, you choose to apply the waiting list features only to products listed in the exclusion list.
Relative to the previous example, The waiting list button will show only on the YITH Car and YITH Mug (when they are out of stock).