VF11 - Any exit / routine to add customer tab for Saving extra info

Hi Friends,

The billing document numbers are cancelled through T-Code 'VF11'...

The requirement is : The reason for cancelling the document shuold aslo be captured somehow in the screen .. ( the user will select from a given list of reasons .. and that should be captured and saved DB )

Is there any provision for this ??? .. if yes .... how can be done ???? what are the stpes ???

How to go about that ???

Expecting your answers...

Thanks in advance...

Cheers,

R.Kripa