DtdProcessing Enumeration

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Specifies the options for processing DTDs. The DtdProcessing enumeration is used by XmlReaderSettings.

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


Public Enumeration DtdProcessing
public enum DtdProcessing


Member name Description
Supported by Silverlight for Windows PhoneSupported by Xbox 360 Prohibit Specifies that when a DTD is encountered, an XmlException is thrown with a message that states that DTDs are prohibited. This is the default behavior.
Supported by Silverlight for Windows PhoneSupported by Xbox 360 Ignore Causes the DOCTYPE element to be ignored. No DTD processing occurs. Warning: The DTD/DOCTYPE will be lost on output.
Supported by Silverlight for Windows PhoneSupported by Xbox 360 Parse Is used for parsing DTDs.


This enumeration is set on the DtdProcessing property. In .NET Framework for Silverlight, the DtdProcessing property replaces the ProhibitDTD property in .NET Framework and adds the ability to ignore the DOCTYPE element.


The following example preloads the DTDs and entities defined in XHTML 1.0 by setting Xhtml10 on the XmlPreloadedResolver. In this example, the XHTMLPage.html file is a part of the application's XAP package; therefore, we have to pass a fallback resolver to the constructor of the XmlPreloadedResolver.

Dim settings As XmlReaderSettings = New XmlReaderSettings()
settings.XmlResolver = New XmlPreloadedResolver(New XmlXapResolver(), XmlKnownDtds.Xhtml10)
Using reader As XmlReader = XmlReader.Create("HTMLPage.html", settings)
    Dim document As XDocument = XDocument.Load(reader)
    OutputTextBlock.Text = document.ToString()
End Using

XmlReaderSettings settings = new XmlReaderSettings();
settings.DtdProcessing = DtdProcessing.Parse;
settings.XmlResolver =
    new XmlPreloadedResolver(new XmlXapResolver(),

using (XmlReader reader = XmlReader.Create("HTMLPage.html", settings))
XDocument document = XDocument.Load(reader);
OutputTextBlock.Text = document.ToString();

Version Information


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0


For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.