Internal Table: header line

types: begin of POW,
         NUM type I,
         NUM2 type I,
       end of POW.
data: ITAB type POW occurs 0,
      ROW type POW.

do 5 times.
  ROW-NUM = SY-INDEX.
  ROW-NUM2 = SY-INDEX ** 2.
  append ROW to ITAB.
enddo.

* ======================================================================
* "ITAB" is a table without a header line and therefore has no component
* ======================================================================
*do 5 times.
*  ITAB-NUM = SY-INDEX + 5.
*  ITAB-NUM2 = ITAB-NUM ** 2.
*  append ITAB.
*enddo.

loop at ITAB into ROW.
  write: / 'num:', ROW-NUM left-justified, ', num2:', ROW-NUM2.
endloop.

types: begin of POW,
         NUM type I,
         NUM2 type I,
       end of POW.
data: ITAB type POW occurs 0 with header line,
      ROW type POW.

do 5 times.
  ROW-NUM = SY-INDEX.
  ROW-NUM2 = SY-INDEX ** 2.
  append ROW to ITAB.
enddo.

do 5 times.
  ITAB-NUM = SY-INDEX + 5.
  ITAB-NUM2 = ITAB-NUM ** 2.
  append ITAB.
enddo.

loop at ITAB into ROW.
  write: / 'num:', ROW-NUM left-justified, ', num2:', ROW-NUM2.
endloop.