Heard of XHTML? The W3C produced a specification to combine the vocabulary of HTML with the syntax of the eXtensible Markup Language (XML) - but this wasn't popular. According to the creator of the World Wide Web, Tim Berners-Lee, "The attempt to get the world to switch to XML, including quotes around attribute values and slashes in empty tags and namespaces all at once didn't work." The Living Standard for web content is HTML!