using System;

using System.Collections.Generic;

public enum InternationalNumberType

{

    EISBN,

    ISSN,

    ISBN

}

​

​

​

public class LineItem

{

    public KeyValuePair<InternationalNumberType, string> InternationalNumber {get;set;}

}

​

public class Program

{

    public static void Main()

    {

        var lineItem = new LineItem

        {

            InternationalNumber = new KeyValuePair<InternationalNumberType, string>(InternationalNumberType.ISSN, "ABC123")

        };

        Console.WriteLine("Number Type: {0}, Value: {1}", lineItem.InternationalNumber.Key, lineItem.InternationalNumber.Value);

    }

}

​

​

​

​

​