XML document types are implemented with the XDocumentType class.
Document types are meant to be added to an XML document, not an element.
You can create a document type and add it to an XML document on the fly using functional construction.
using System; using System.Linq; using System.Xml.Linq; using System.Collections.Generic; class Program// w w w .j av a2s . c om { static void Main(string[] args){ XDocument xDocument = new XDocument(new XDocumentType("Books", null, "Books.dtd", null), new XElement("Book")); Console.WriteLine(xDocument); } }