Planner codes provide a mechanism for categorizing items for planning purposes. For example, let's say you want to develop separate plans for raw materials versus finished goods. To do so, you would first create separate planner codes: one for materials and one for finished goods. You would then link the materials planner code to the item sites for your materials—and the finished goods planner code to the item sites for your finished goods. From that point on, you can run the planning systems and planning reports by individual planner codes to see the detail separately for each.