An extreme change in the supply position upstream in a supply chain generated by a small change in demand downstream in the supply chain. Inventory can quickly move from being backordered to being excess. This is caused by the serial nature of communicating orders up the chain with the inherent transportation delays of moving product down the chain.

  A technique for calculating operation start dates and due dates.  The schedule is computed starting with due date for the order and working backward to determine the required start date and/or due dates for each operation.