Filter User Defined Table

Dear All,

I have created a User defined table @A. And in the Service Title screen i have create a User defined field U_A.

I have linked this user defined field to @A. The field U_A display all the values in the @A table. I want filter the data that is display in U_A.

e.g if @A has all the PO numbers.Currently it display all the PO numbers.I want it to display only Open PO's.

Kindly suggest.

Thanks,

Merle