How to get user exits for Tcode ME22N to add a text field on the screen

Hi All,

I want to add a text field on the screen of ME22N.

This text field will contain the reason for no GR which has to be saved in a ZTable with PO being the key field of this table.

Is there a possibility of any enhancement in ME22N wherein we can create an input output field on the main screen or any of the subscreen of ME22N.

Regards,

Vidya .