Drill Down Report

Few Pointers -
HIDE - The values to be passed into the next level should be put in this statement.
SY-LSIND - The level of the list that is being displayed
You can drill down to 20 levels.

Sample Report -
tables: kna1, vbak, vbap.
select-options: s_kunnr for kna1-kunnr.
data: begin of itab occurs 0,kunnr like kna1-kunnr,name like kna1-name1,end of itab.
data: begin of jtab occurs 0,vbeln like vbak-vbeln,netwr like vbak-netwr,end of jtab.
data: begin of ktab occurs 0,posnr like vbap-posnr,matnr like vbap-matnr,end of ktab.
data: v_fnam(10), v_fval(10).
start-of-selection.
select kunnr name1 from kna1 into table itab where kunnr in s_kunnr.
loop at itab.write:/ itab-kunnr hotspot, itab-name.hide itab-kunnr.endloop.
at line-selection.
case sy-lsind.
when 1.select vbeln netwr from vbak into table jtab where kunnr = itab-kunnr.
loop at jtab.write:/ jtab-vbeln hotspot, jtab-netwr.hide jtab-vbeln.endloop.
when 2.
select posnr matnr from vbap into table ktab where vbeln = jtab-vbeln.
loop at ktab.write:/ ktab-posnr, ktab-matnr hotspot.endloop.
when 3.get cursor field v_fnam value v_fval.set parameter id 'MAT' field v_fval.call transaction 'MM02'.
endcase.
top-of-page.write:/ 'Custom Deatils Report'.
top-of-page during line-selection.
case sy-lsind.
when 1.write:/ 'Sales Details Report'.
when 2.write:/ 'Item Details Report'.
endcase.