Gets the Document Type Definition (DTD) for this document.
Assemblies: System.Xml.XDocument (in System.Xml.XDocument.dll)
System.Xml.Linq (in System.Xml.Linq.dll)
LINQ to XML provides limited support for DTDs.
You can populate an XML tree with an XML document that contains a DTD. The XML tree will then contain a node. When you serialize or save the tree, the DTD will also be serialized. LINQ to XML will expand any entities in the DTD. When you serialize or save the XML tree, the entity references are not saved; instead, the nodes are saved with the entity references replaced by the text of the entity.
If the DTD contains default attributes, the attributes are created in the XML tree as ordinary attributes.
By default, LINQ to XML does not validate a document based on its DTD. To validate a document based on a DTD, create an XmlReader that will validate based on a DTD, and then create an XML tree from the XmlReader.
The following example creates a document that contains an XDocumentType.
Visual Basic does not support document types within XML literals. However, it is possible to create a document that contains a document type by first creating the document using XML literals, and then creating and adding an XDocumentType node in the appropriate place in the XML tree.
string internalSubset = @"<!ELEMENT Pubs (Book+)> <!ELEMENT Book (Title, Author)> <!ELEMENT Title (#PCDATA)> <!ELEMENT Author (#PCDATA)>"; string target = "xml-stylesheet"; string data = "href='mystyle.css' title='Compact' type='text/css'"; XDocument doc = new XDocument( new XComment("This is a comment."), new XProcessingInstruction(target, data), new XDocumentType("Pubs", null, null, internalSubset), new XElement("Pubs", new XElement("Book", new XElement("Title", "Artifacts of Roman Civilization"), new XElement("Author", "Moreno, Jordao") ), new XElement("Book", new XElement("Title", "Midieval Tools and Implements"), new XElement("Author", "Gazit, Inbar") ) ), new XComment("This is another comment.") ); doc.Declaration = new XDeclaration("1.0", "utf-8", "true"); Console.WriteLine(doc); doc.Save("test.xml");
This example produces the following output:
<!--This is a comment.--> <?xml-stylesheet href='mystyle.css' title='Compact' type='text/css'?> <!DOCTYPE Pubs [<!ELEMENT Pubs (Book+)> <!ELEMENT Book (Title, Author)> <!ELEMENT Title (#PCDATA)> <!ELEMENT Author (#PCDATA)>]> <Pubs> <Book> <Title>Artifacts of Roman Civilization</Title> <Author>Moreno, Jordao</Author> </Book> <Book> <Title>Midieval Tools and Implements</Title> <Author>Gazit, Inbar</Author> </Book> </Pubs> <!--This is another comment.-->
.NET FrameworkSupported in: 4.6, 4.5, 4, 3.5
.NET Framework Client ProfileSupported in: 4, 3.5 SP1
XNA FrameworkSupported in: 3.0
Portable Class LibrarySupported in: Portable Class Library
Supported in: Windows Phone 8.1
Supported in: Windows Phone Silverlight 8.1
Supported in: Windows Phone Silverlight 8