Many thanks Chinthan - yes I was experimenting with Personas drop-downs originally but now I am using the SAP ECC drop down which seems better and more efficient (as I don't need to maintain the values in the Personas drop down manually). The problem is the user can select a value from the drop down (as it's the SAP match code, not Personas drop down) but they can by pass this and key a random (invalid) value in as well. Of course I can validate at the back end but I just wondered if there was a way of stopping an invalid value being sent down the line.
Regards.
Patrick