using System;

using System.Collections.Generic;

using System.Xml;

using System.Xml.Serialization;

using System.Xml.Schema;

using System.IO;

public class Program

{

    public static void Main()

    {

        var xml = @"<?xml version=""1.0"" encoding=""utf-16""?>

<PurchaseOrder xmlns:xsd=""http://www.w3.org/2001/XMLSchema"" xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"">

  <Item1>

    <one>1</one>

  </Item1>

  <Item2>

    <two>2</two>

  </Item2>

</PurchaseOrder>

";

        XmlSerializer serializer = new XmlSerializer(typeof(PurchaseOrder));

​

//StreamReader reader = new StreamReader(path);

 var items = (PurchaseOrder)serializer.Deserialize(new StringReader(xml));

//reader.Close();

        //Console.WriteLine((items.ItemsOrders[0] as Item1).one);

        Console.WriteLine((items.ItemsOrders[1] as Item2).two);

​

        var po = new PurchaseOrder();

        //po.ItemsOrders.Add(new Item1() {

        //  

        //  one = 1

        //});

        po.ItemsOrders.Add(new Item2() {

            two = 2

        });

        System.Xml.Serialization.XmlSerializer x = new System.Xml.Serialization.XmlSerializer(po.GetType());

        x.Serialize(Console.Out,po);

        Console.WriteLine();

        Console.ReadLine();

    }

}

​

public class PurchaseOrder  

{  

    [XmlElement(ElementName="Item1", Type=typeof(Item1))]

    [XmlElement(ElementName="Item2", Type=typeof(Item2))]

    public List<Item> ItemsOrders = new List<Item>();

}  

​

[XmlInclude(typeof(Item1))]

[XmlInclude(typeof(Item2))]

public abstract class Item

{  

    public void nooop() {

    }

}  

​

public class Item1 : Item

{  

    public int one {get;set;}

}  

​

public class Item2 : Item

{  

    public int two {get;set;}  

}