Confusion in XML

private const localURL as String = " http://localhost/quickstart/howto/samples/Xml/QueryXmlDocume ntXPath/cs/books.xml"

Shared sub Main
    Dim myQueryXmlDocumentXPathSample as QueryXmlDocumentXPathSample
    myQueryXmlDocumentXPathSample = new QueryXmlDocumentXPathSample()
    myQueryXmlDocumentXPathSample.Run(localURL)
end sub

public sub Run(args as String)
    Console.WriteLine("XPath Test started ...")

    Dim myXPathDocument as XPathDocument = new XPathDocument(args)
    Dim myXPathNavigator as XPathNavigator = myXPathDocument.CreateNavigator()

    ' Get all the book prices
    XPathQuery(myXPathNavigator, "descendant::book/price")

    ' Get the ISBN of the last book
    XPathQuery(myXPathNavigator, "bookstore/book[3]/@ISBN")
end sub

private sub XPathQuery(myXPathNavigator as XPathNavigator, xpathexpr as String )

    try
        Console.WriteLine("XPath query: " + xpathexpr)

        ' Create a node interator to select nodes and move through them (read-only)
        Dim myXPathNodeIterator as XPathNodeIterator  =  myXPathNavigator.Select (xpathexpr)

        while (myXPathNodeIterator.MoveNext())
             Console.WriteLine("<" & myXPathNodeIterator.Current.Name + "> " & myXPathNodeIterator.Current.Value)
        end while

        Console.WriteLine()
    catch e as Exception
        Console.WriteLine ("Exception: {0}", e.ToString())
    end try
end sub