Planned Withdrawal of Material Components 
Use
When a process order is created, the system automatically creates a reservation for the necessary material components. Each material component in the order is dealt with under a different item number in the reservation. The reserved materials cannot be issued from stock until the operation or phase to which they are assigned in the order has been released.
There are two ways in which you can post a goods movement:
R/3 Integration Using Process Messages; PI CONS)
If the ‘backflush’ indicator is set for a component contained in the material list, the goods issue is posted automatically when you create the confirmation for the respective phase.
For more information on how to control whether a material is backflushed, see
Backflushing.The withdrawal of the components causes the value of the components issued to be debited to the order for each cost element and origin as actual costs.
To issue material components from stock, you can either refer to the order number or to the reservation number. The reservation number is displayed in the general data screen of the components.
Procedure
To issue material components from stock, proceed as follows:
– The system automatically proposes the movement type 261 (goods issue for order) as well as all the material components in the order that are not marked as bulk material or as material to be backflushed.

If you do not refer to a reservation or to a process order when you post a goods issue, the reservations remain open and the required quantity reserved, even though the requirement no longer physically exists.