using System;

using System.Xml;

public class Program

{

    public static void Main()

    {

        var ns = "http://made.up/uri";

        var doc = new XmlDocument();

        doc.AppendChild(doc.CreateXmlDeclaration("1.0", "utf-8", null));

        var policies = doc.AppendChild(doc.CreateElement("policies"));

        var att = policies.Attributes.Append(doc.CreateAttribute("xmlns"));

        att.Value = ns;

        var policy = policies.AppendChild(doc.CreateElement("policy"));

        policy.InnerText="bla";

//      doc.LoadXml(doc.OuterXml);

        var namespaces = new XmlNamespaceManager(doc.NameTable);

        namespaces.AddNamespace("pol", ns);

​

​

        var policyNodes = doc.SelectNodes("//pol:policy", namespaces);

        if (policyNodes.Count == 0){

            Console.WriteLine("No policy nodes");

        }else{

            Console.WriteLine("Found policy nodes");

        }

        Console.WriteLine(doc.OuterXml + "\n" + DateTime.Now);

    }

}