using System;

using System.Text;

using System.Xml;

​

public class Program

{

    public static void Main(string[] args)

    {

        var sb = new StringBuilder();

        var writer = XmlWriter.Create(sb, new XmlWriterSettings

        {

            OmitXmlDeclaration = true,            

        });

​

        using (writer)

        {

            writer.WriteStartElement("x", "node", "uri:special-x");

            writer.WriteAttributeString("xmlns", "uri:default");

            writer.Flush();

            sb.Append("\n" + new string(' ', 7));

            writer.WriteAttributeString("xmlns", "x", null, "uri:special-x");

            writer.Flush();

            sb.Append("\n" + new string(' ', 7));

            writer.WriteAttributeString("xmlns", "y", null, "uri:special-y");

            writer.Flush();

            sb.Append("\n" + new string(' ', 7));

            writer.WriteAttributeString("name", "uri:special-y", "vd");

            writer.Flush();

            sb.Append("\n" + new string(' ', 7));

            writer.WriteAttributeString("SomeOtherAttr", "ok");

            writer.WriteEndElement();

        }

​

        Console.WriteLine(sb);

    }

}