using System;

using System.Xml;

using System.Xml.Linq;

using System.Linq;

using System.Xml.XPath;

using System.Collections.Generic;

public class Program

{

    public struct things {

        public int item1;

        public string item2;

        public float item3;

    }

    public static void Main()

    {

        int majorItem1 = 15;

        float majorItem2 = 22.6f;

        string majorItem3 = "this string";

        List<things> items = new List<things>();

        things x1 = new things();

        x1.item1 = 2;

        x1.item2 = "x1";

        x1.item3 = 4;

        items.Add(x1);

        things x2 = new things();

        x2.item1 = 5;

        x2.item2 = "x2";

        x2.item3 = 28;

        items.Add(x2);

        things x3 = new things();

        x3.item1 = 12;

        x3.item2 = "x3";

        x3.item3 = 100;

        items.Add(x3);

        XDocument doc = new XDocument(

            new XDeclaration("1.0", "utf=8", "true"),

            new XElement("Data",

                         new XElement("majorItem1", majorItem1),

                         new XElement("majorItem2", majorItem2),

                         new XElement("majorItem3", majorItem3),

                         new XElement("List")

            )

        );

        doc.Root

           .Element("List")

            .Add(from item in items

                 select new XElement("item",

                                     new XElement("item1", item.item1),

                                     new XElement("item2", item.item2),

                                     new XElement("item3", item.item3)

                                    ));

        Console.WriteLine(doc.ToString());

    }

}