In most supply chain efforts, the need to cope with how orders are received and passed into the planning process and on to manufacturing or production was dealt with early in the improvement process. In most instances, the participants found there was an absence of solid methodology for accomplishing this task in an efficient manner. Although data was passed forward, there were always questions concerning the accuracy of the demand figures, the confidence in the inventory data, the reliability of production schedules, and so forth. Then sales and operations planning (S&OP) entered the picture and became a staple of supply chain efforts beginning in the early 1990s. With maturity of the supply chain efforts, many firms have made strides in this area while others have gone well beyond this type of effort. As a result, most organizations have progressed to a form of advanced planning and scheduling (APS), which will be explained in the next chapter.