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XDocument.DocumentType Property

Gets the Document Type Definition (DTD) for this document.

Namespace:  System.Xml.Linq
Assembly:  System.Xml.Linq (in System.Xml.Linq.dll)

public XDocumentType DocumentType { get; }

Property Value

Type: System.Xml.Linq.XDocumentType
A XDocumentType that contains the DTD for this document.

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 DocumentType 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 Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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