Handling NULL Values Using $FLEX$ in Value Sets

To Handle The Null Values In Value Set Please find the Below One, Hope it is Helpful for All Techies.

SELECT SHIPMENT_NUM
FROM RCV_SHIPMENT_HEADERS

WHERE CLAUSE: SHIPMENT_HEADER_ID in
(select shipment_header_id from rcv_shipment_lines
where shipment_line_status_code NOT IN('FULLY RECEIVED','CANCELLED')
and from_organization_id=NVL(:$FLEX$.IFF_WMS_ORGANIZATION1:NULL,from_organization_id)
and to_organization_id=:$FLEX$.IFF_WMS_ORGANIZATION)
and receipt_source_code not in ('VENDOR')


Ur's
AmarAlam