Query to drill down from PO header to shipment

SELECT poll.*
  FROM po_headers_all poh,
       po_releases_all pora,
       po_lines_all pla,
       po_line_locations_all poll
 WHERE     poh.po_header_id = pora.po_header_id
       AND pla.po_line_id = poll.po_line_id
       AND poll.po_release_id = pora.po_release_id
       AND poh.segment1 = :po_number
       AND pora.release_num = :po_release_num
       AND pla.line_num = :po_line_num
       AND poh.org_id = :org_id;