Stacking rules can result in promotions being excluded from use in a customer’s shopping cart. In order to make it clear to the customer why a promotion has been excluded, the Order Summary portion of the shopping cart page has a “Where did my promotion go?” link. The store.war/checkout/gadgets/checkoutOrderSummary.jsp page renders this link only if there are stacking rule exclusion messages in the CleanBeforePricingSlot. If there are messages in the slot, checkoutOrderSummary.jsp renders a link to the store.war/global/gadgets/promotionDetailsPopup.jsp page. Using a TargetingArray droplet, this popup page retrieves and renders all of the messages in the CleanBeforePricingSlot. Note that, unlike gift with purchase messages, we do not need to filter out any stacking rule exclusion messages from the CleanBeforePricingSlot because this slot is cleared out before each pricing operation. This ensures that only up-to-date messages related to the latest pricing operation exist in the slot.