User exit in SAPMV50A to READ and SAVE TEXT from PO

Hi Experts,

I have an requirement for "Copying PO Header Text to Delivery Text". I have already created TEXT ID's , Access Sequence and assigment to Delivey type in VOXTN.

Could you please suggest "User exit in the delivery program SAPMV50A, tcode VL01N, to READ and SAVE TEXT from PO.

In the user exit I will user READ_TEXT FM using the custeom id created.

Thanks

Krishan