Radio buttons

Hi all ,

I have two radio buttons in my code ,

1) r1

2 ) r2

if i select r1 radio button , in select options

s_vgart for rbkp-vgart default value must be 'RS' and if i

select r2 radio button default value must be 'RD' .

My code :

PARAMETERS : r1 RADIOBUTTON GROUP rg1,

r2 RADIOBUTTON GROUP rg1 DEFAULT 'X'.

SELECT-OPTIONS : s_vgart for rbkp-vgart DEFAULT 'RD'.

Plz give code for this .

Points will be given soon .