title: "instance of" equivalent in Schematron/XPath
body: <p>I have found that Saxon implementation of XPath 2.0 supports both 'instance of' and 'castable as' as valid ways of obtaining the type of a value, <a href="http://xfront.com/awesome-power-of-schematron-plus-xpath2/index.html" rel="nofollow">as explained in this website</a>.
  This seems to be a Saxon specific syntax. Does a standard way of obtaining the type of a node exist?</p>