Public MustOverride ReadOnly Property MainDataSource As DataSource

Dim instance As XmlForm
Dim value As DataSource

value = instance.MainDataSource

public abstract DataSource MainDataSource { get; }

public void FormEvents_Loading(object sender, LoadingEventArgs e)
{
   // Create XPathNavigator positioned at the root of the main data 
   // source.
   XPathNavigator myNav = this.MainDataSource.CreateNavigator()

   // Select employee field and set value to username.
   myNav.SelectSingleNode("//my:employee",this.NamespaceManager).
      SetValue(System.Environment.UserName);
}

Public Sub FormEvents_Loading(ByVal sender As Object, ByVal e As LoadingEventArgs)
   ' Create XPathNavigator positioned at the root of the main data 
   ' source.
   Dim myNav As XPathNavigator = Me.MainDataSource.CreateNavigator()

   ' Select employee field and set value to username.
   myNav.SelectSingleNode("//my:employee", Me.NamespaceManager). _
      SetValue(System.Environment.UserName)
End Sub