Ordering systems are the "mechanical" part of inventory management. They are programs that take our forecasts, actual orders, security stocks and, and order quantities, and convert them into purchase orders or production orders. Due to its mechanical nature, there is not much theory when it comes to ordering systems. But that does not mean there are not things you need to know.
Although basic ordering systems are covered, the main point of the book is to cover more functional ordering systems such as order point of time, material requirements planning (MRP) and distribution requirements planning (DRP).