If the requirements situation has changed, the system adjusts the dates and quantities of order proposals (planned orders, purchase requisitions and schedule lines) that are automatically created in the planning run. To prevent the system from automatically changing order proposals, you can firm them. The system does not change firm order proposals in the planning run. That is, the system does not change the quantities and dates.
In release 4.0, a manual firming date is available in addition to the planning time fence for firming order proposals. You can use the manual firming date in MRP, master production scheduling and long-term planning.
You define the manual firming date in the stock/requirements list. It must be a date that lies after the end date of the planning time fence which is defined for a material in the material master record or per MRP group in Customizing. The system does not automatically change order proposals up to this date.
If you set a manual firming date, the system firms all order proposals with order finish dates before this date if the materials have an MRP type which contains no firming type or firming type 1 or 2.
The system does not automatically firm order proposals for materials that have an MRP type with firming type 3 or 4, even if their order finish dates lie before the manual firming date.
Materials with an MRP type without a firming type are treated as materials with firming type 1.