The PromotionalContent-ATGSlot and PromotionalContent-ATGTargeter cartridges display promotional content items in the left-hand rail of both the Category Page and the Default Browse Page. The ProductSpotlight-ATGSlot and ProductSpotlight-ATGTargeter cartridges are not used out of the box but are available for developers who base their application on Commerce Reference Store. The content for these cartridges is provided by ATG slots and targeters that have been defined in the ATG Control Center and the Business Control Center, respectively. All four cartridges, collectively referred to as the “targeting cartridges” in this section, have a similar structure, described below.