XML documents can be validated against an XML schema definition language (XSD) schema in an Xml Schema Set.
XML documents are validated by the Create method of the Xml Reader class. Schema namespace contains extension methods that make it easy to validate an XML tree against an XSD file when using LINQ to XML.
For more information about read-only and editable XPath Navigator objects, see the Reading XML Data using XPath Document and Xml Document topic.
The XPath Document object validates the XML document as it is loaded, but because you cannot edit the XML data in the XPath Document object, you cannot revalidate the XML document.
In both cases, changes to the validated XML document can be revalidated using the Validate method of the Xml Document class. The following example validates the Imports System Imports System. object is null, schema locations are not resolved even if the Process Inline Schema and Process Schema Location validation flags are set.Schemas added during validation add new types and can change the validation outcome of the document being validated. In the case of validation, you can create an XPath Document object just like you create an Xml Document object using a validating Xml Reader object as described earlier in this topic. Because the XPath Document class is a read-only class, XPath Navigator object's returned from XPath Document objects cannot edit the XML document contained in the XPath Document object.
Note that when validating a document the target namespace of the document must match the target namespace of the schema in the schema set. In the code example that follows, the schema above is added to the Xml Schema Set Schemas property of the Xml Reader Settings object.