Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
  Const schemaPath As String = "c:\AddressBook.xsd"
  Const documentPath As String = "c:\sample001.xml"
  Dim doc As XmlDocument = New XmlDocument
  Dim reader As XmlValidatingReader = New XmlValidatingReader( _
    New XmlTextReader(documentPath))
  reader.Schemas.Add(Nothing, schemaPath)
  reader.ValidationType = ValidationType.Schema
  doc.Load(reader)
End Sub