<?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML+RDFa 1.0//EN" "http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd"> <html xml:lang="en" xmlns="http://www.w3.org/1999/xhtml" xmlns:rss="http://purl.org/rss/1.0/"> <head> <title>Hello World!</title> </head> <body> <h1>Hello World!</h1> </body> </html>