Get country's internal id, i.e "_unitedStates", not display value ie "US"

Hi,

I'm writing a web service that will receive updates from CRM via nlapiRequestUrl(). I have the need to pass country information, but passing "US" or "United States" doesn't help me since we also use web services and we have mapped countries in our database using the enum values (_unitedStates, _canada, etc).

Is there a way from client script to obtain this _xxxxx value for a country instead of the display or text value in the dropdown (when working with the addressbook sublist of a customer)?

For example, one of the values that I'm passing to my webservice is:

//indexMain is the index of the customer's main address  currentCountry = nlapiGetLineItemValue('addressbook','country',indexMain);