Tools are free and portable. XSLT technology is new. Tools aren't well packaged. Writing XML code isn't for everyone. The XML document is processed with the Xalan XSLT processor which uses the Xerces XML parser.
Search engines have to make guesses about page categories by looking at the contents.
The Semantic Web is a W3C activity aimed at setting standards for Meta Data on the web. The RDF specifications provide a lightweight ontology system to support the exchange of knowledge on the Web. In this case we are using the standard Dublin Core set of metadata elements. This example also illustrates the use of XML Namespaces to differentiate XML element names. This is the example from the previous slide.