Hi Ralf
Not sure if I got it right. Are you specifically looking for a solution only using constructs introduced with ABAP 7.4?
Otherwise, old school conditional checks would work. And I believe for a char field " " (one space) and " " (two spaces) have the same content.
LOOP AT partner_tab ... WHERE partn_role NE space .
...
ENDLOOP .
or
...
IF ...-partn_role NE space .
...
ENDIF .
A READ TABLE equivalent existence check with excluded specific values for a field can be achieved with a LOOP.
LOOP AT partner_tab TRANSPORTING NO FIELDS WHERE partn_role NE space .
EXIT .
ENDLOOP .
IF sy-subrc = 0 .
" Process for the case when there are partners with roles other than space
ENDIF .
Hope this helps.
*-- Serdar