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LINQ to XML : Understanding Annotations

Annotations are used for private use. It does not directly associated and known as Black Box in XML world. This can also be considered as meta tag.

Below is an example on how it can be handled. I have created a sample Windows Applications and will try to capture my understanding.

/// <summary>

/// Class for the Structure of the Data

/// </summary>

public class DataClass


    public int ID { get; set; }

    public string Name { get; set; }

    public string Email { get; set; }



public static XElement xmlData = new XElement(“family”);

private void Form2_Load(object sender, EventArgs e)


    //Create a List in memory

    List<DataClass> lstData = new List<DataClass>


        new DataClass(){ID = 1, Name = “Debajyoti”, Email = “d@contoso.com”},

        new DataClass(){ID = 2, Name = “Sumitra”, Email = “s@contoso.com”},

        new DataClass(){ID = 3, Name = “Wriju”, Email = “wg@contoso.com”},

        new DataClass(){ID = 4, Name = “Tupur”, Email = “t@contoso.com”},

        new DataClass(){ID = 5, Name = “Writam”, Email = “w@contoso.com”},



    //Here create the XML which will hold the info also an annotation

    foreach (DataClass data in lstData)


        XElement member = new XElement(“member”,

            new XAttribute(“ID”, data.ID),

            new XAttribute(“Name”, data.Name));


        //Adding Annotation to the element






    //Loading the List holding two values ID and Name

    listBox1.DataSource = lstData;

    listBox1.DisplayMember = “Name”;

    listBox1.ValueMember = “ID”;




private void listBox1_SelectedIndexChanged(object sender, EventArgs e)


    if (listBox1.SelectedIndex > 0)


        //By ID we will capture the element to get the annotation

        var email = xmlData.Descendants(“member”).

            First(el => el.Attribute(“ID”).Value == listBox1.SelectedValue.ToString());


        //Get the annotation to print that out.

        label1.Text = email.Annotations<String>().First();