AT New in Report and their use

REPORT ABC.

DATA : BEGIN OF ITAB OCCURS 0,
bukrs like t001-bukrs,
f1(10) type c,
end of itab.

itab-bukrs = '1000'.
itab-f1 = '1111111'.
append itab.

itab-bukrs = '1100'.
itab-f1 = '3333333'.
append itab.

itab-bukrs = '1200'.
itab-f1 = '555555'.
append itab.

*------------ AT NEW

loop at itab.
at new bukrs.
write :/ itab-bukrs , itab-f1.
endat.

endloop.
*------------ AT ONCHANGE

loop at itab.
ON CHANGE OF ITAB-BUKRS.
write :/ itab-bukrs , itab-f1.

ENDON.

endloop.