The third dimension is control over the value chain encompassing all functional groups (finance, supply/procurement, marketing, inventory, information technology etc..) to ensure low costs. For supply/procurement chain, this could be achieved by bulk buying to enjoy quantity discounts, squeezing suppliers on price, instituting competitive bidding for contracts, working with vendors to keep inventories low using methods such as Just-in-Time purchasing or Vendor-Managed Inventory. Wal-Mart is famous for squeezing its suppliers to ensure low prices for its goods. Other procurement advantages could come from preferential access to raw materials, or backward integration. Keep in mind that if you are in control of all functional groups this is suitable for cost leadership; if you are only in control of one functional group this is differentiation. For example, Dell Computer initially achieved market share by keeping inventories low and only building computers to order via applying Differentiation strategies in supply/procurement chain. This will be clarified in other sections.