CRM 4.0 - Order Cancel status reason - blank value

Hi All,

I am working on CRM 4.0. I want to add "Unassigned Value" as default value under statuscode(status reason) field at Order screen. But I don't find this option during customization. I think this option comes on only of type "Picklist". Can anyone help me, how to achieve this for statuscode? I want to make it required field and add "Unassigned Value" as default value.

I am doing this because on Order Close dialogue (opened when we cancel the order), by default first value get selected. I want user must select appropriate option from the list.

Thanks,

Ravi