I know that this is a very old string, but I tripped across it while searching to accomplish the same objective. After some searching/struggling was able to create such an Infoset Query. Jelena's comment is correct to an extent - "Extras" are used, as are some additional work-arounds....
What I did was:
- Created an infoset with tables/links MCH1-LVORM = AUSP-LKENZ
- Created an "Extra" Addnl Field "FIRST18" with associated coding of "FIRST18 = AUSP-OBJEK+0(18)."
- Created an "Extra" Addnl Table "INOB", deifned as "SELECT SINGLE * FROM INOB WHERE CUOBJ = FIRST18"
- Created a Code instruction "CHECK INOB-CUOBJ = MCH1-CUOBJ_BM."
Hope this helps.