A blanket order is a contract placed with a customer corresponding to an commitment for quantities and price for a single item over the period of validity of contract. This practice avoids creating as many orders as of desired deliveries.
One must indicate the item number concerned.
The lines of the blanket order correspond to delivery requests for the same item.
You can add lines and validate them individually.
When all the lines are dispatched (they all are with the status C), it is possible to close the blanket order. On the sales order maintenance page appears a Closing button. After closing, the order gets the status C (Closed) and it is no more possible to add new lines.