For a query, you must specify the field lists in the DEFINE QUERY statement, not the Record Phrase of the OPEN QUERY statement. Thus, the following two procedures, i-fldls1.p and i-fldls2.p, are functionally equivalent.

i-fldls1.p

DEFINE QUERY custq FOR Customer FIELDS(Name CustNum Balance).
OPEN QUERY custq PRESELECT EACH Customer.
REPEAT:
  GET NEXT custq.
  IF AVAILABLE(Customer) THEN
    DISPLAY Customer.Name Customer.CustNum Customer.Balance.
  ELSE LEAVE.
END.

i-rldls2.p

REPEAT PRESELECT EACH Customer FIELDS (Name CustNum Balance):
  FIND NEXT Customer.
  DISPLAY Customer.Name Customer.CustNum Customer.Balance.
END.