JSPX lets you create dynamic documents in a pure XML syntax compatible with existing XML tools. The XML syntax in JSP 1.2 was awkward and required <jsp:root> to be the root element of the document. This is no longer the case in JSP 2.0.
This particular example uses a tag file to produce the DOCTYPE and namespace declarations to make the output of this page a valid XHTML Basic document.
Just to prove this is live, here's some dynamic content: Mon Feb 03 10:26:15 ICT 2025