using System.Collections.Generic;
public static void Main()
XmlWriterSettings settings = new XmlWriterSettings();
settings.OmitXmlDeclaration = true;
settings.ConformanceLevel = ConformanceLevel.Auto;
settings.CloseOutput = false;
MemoryStream strm = new MemoryStream();
XmlWriter writer = XmlWriter.Create(strm, settings);
writer.WriteElementString("orderID", "1-456-ab");
writer.WriteElementString("orderID", "2-36-00a");
string xml = Encoding.UTF8.GetString(strm.ToArray());
Console.WriteLine("exit");