Without systems that support a collaborative demand plan established through a bottoms-up store-level DRP process, business execution visibility is short-term and orders are often a surprise (as if they were tossed over a wall). Each trading partner forecasts its demand independently, limiting category or market insights that could be shared between key suppliers and retailers. A history of past supply chain outages may drive each trading partner to build buffer stocks to avoid the risk of out-of-stocks. The inevitable supply chain overages and outages regularly result in adversarial buyer-seller relationships