Screen Field RM06E-UMSON does not exist in a table but is derived or implied by the status of other fields for the line item. For example as found in Program SAPLMEPO and Form LESEN_BELEG:
* set the indicator for free shipment
IF pot-repos EQ space AND pot-pstyp NE pstyp-kons AND
pot-pstyp NE pstyp-umlg.
pot-umson = 'X'.
ENDIF.
This implies that if the REPOS field (Invoice Receipt) is Blank and the PSTYP field (Item Category) is not Consignment(Value 2) or Stock Transfer(Value 7) then this is a Free Shipment item.
