At Level 1, the master scheduling process considers individual parts that can be built, stocked, and shipped to customers. When you aggregate Level 1 parts, you combine the forecasts and other data such as actual demand, unconsumed forecasts, and supply for all the Level 1 parts that belong to the same Level 0 family. A family is a group of parts that are similar enough that they can be treated as one unit for planning purposes. To have correct result it is important to perform MS Level 1 calculation first before the aggregation process take place. At the end of the aggregation process, the system will perform an MS Level 0 calculation. It creates a master schedule which is a manufacturing plan. The calculation also suggests new orders and actions for existing orders. In addition, MS results in a gross demand, which forms the basis of material requirement planning (MRP). When the calculation is complete, you can study the plan for the Level 0 part. The results are grouped by period.
Unlike the disaggregation process, the aggregation process does not use planning structure percentages.