using System;
using Rsdn.Framework.Data;
using Rsdn.Framework.Data.Mapping;

namespace ConsoleApp
{
    public enum TriState     {Yes, No, NotApplicable};

    public class TestMap
    {
        [STAThread]
        static void Main(string[] args)
        {
            TestMap.TestChangeType();
        }

        public class Src
        {
            public string Field1 = "no";
        }

        [MapXml("Dest")]
        public class Dest
        {
            private TriState _f1 = TriState.NotApplicable;

            public TriState Field1
            {
                get
                {
                    return _f1;
                }
                set
                {
                    _f1 = value;
                }
            }
        }

        public static void TestChangeType()
        {
            MapDescriptor.SetMappingSchema(@"D:\Projects\Research\RSDNTest\Mapping.xml");
            Src  s = new Src();
            Dest d = (Dest)Map.ToObject(s, typeof(Dest));

            string temp = d.Field1.ToString();
            Console.WriteLine(temp);
        }
    }
}

<?xml version="1.0" encoding="utf-8" ?>
<mapping xmlns="http://www.rsdn.ru/mapping.xsd">
    <type name="Dest">
    </type>
    <value_type name="TriState ">
        <value target="Yes" source="yes" source_type="System.String" />
        <value target="No" source="no" source_type="System.String" />
        <value target="NotApplicable" source="(n/a)" source_type="System.String" />
        <null_value target="NotApplicable" />
        <default_value target="NotApplicable" />
    </value_type>
</mapping>