Field help (CLEFLG3) 

Help common to functions: Shipments, Shipment pre-receipt and Order pre-receipt.

This non modifiable field indicates whether the line is closed or not in view of its receipt and pre-receipt.

The line is automatically closed when the receipt is closed.

You can also manually close a shipment/pre-receipt line or the whole shipment/pre-receipt in one of the following situations:

Click Close from the Actions icon in order to manually close a shipment/pre-receipt line.
Click Ship. closed from the Actions icon in order to completely close the shipment/pre-receipt.