Use the Change purchase status process to assign a new status to purchase lines.

This process enables you to convert purchase offer lines into purchase order lines, and to assign the other offer lines (the ones that will not be turned into an order) a 'History' status at the same time.

Note: There can only be one purchase order for an external operation: if the external operation already has a purchase line with a status of the 'Order' type, it will not be possible to convert a purchase offer line into a purchase order line for that external operation.