Doubt In VA01 User Exit........

Hi,

we are using <b>sap4.7.</b> In VA01 ( sales Order ) we have a tab called <b>additional data B</b>. where we can write our own user exit coding.

my doubt is where can i find <b>user exit</b> <b>enhancement</b>. i tried in <b>smod t.code</b> but i am not able to find. can any one tell me the enhancement name if you already done.

thank you,

Regards,

Saravanan.