Display Combobox Item Value not Export value (Acrobat Form)

Hi,

Can someone help me please. In combobox Options, you enter an item with corresponding export value:

Item     Export value

USA     AAA

CHI      AAB

ITA      AAC

As I understand, to display/get the combobox value when you select USA, this.getField("comboboxname").value which will give AAA

If I need to get the value of the selected item ex, USA, what code do I use?

Thank You.