REPORT  Z13_013                                                     .
DATA: BEGIN OF s,
        a TYPE c VALUE '1',
        b TYPE c VALUE '2',
        c TYPE c VALUE '3',
        d TYPE c VALUE '4',
        e TYPE c VALUE '5',
        f TYPE c VALUE '6',
        g TYPE c VALUE '7',
        h TYPE c VALUE '8',
      END OF s.

DATA off TYPE i.

FIELD-SYMBOLS <fs> TYPE ANY.

ASSIGN s-a TO <fs>.

DO 4 TIMES.
  off = sy-index - 1.
  IF <fs> IS ASSIGNED.
    ASSIGN <fs>+off(1) TO <fs>.
    IF <fs> IS ASSIGNED.
      WRITE <fs>.
    ENDIF.
  ENDIF.
ENDDO.