Meaning of User Exit in V_T147I

Hi Expert.

Please help me.

We are looking for SAP Standard Vendor Evaluation Process .

Here we seen V_T147I view(sm30) have one field is User Exit. We thing for enhance purpose.

But How it Use because here we write only 1 char.

Said Solution : How can we use this field. OR Describe the Use of field with Example.

Thanks.

Pradip Patel.