Namespaces in XML 1.0 (Third Edition), Tim Bray, Dave Hollander, Andrew Layman,
et. al., Editors. World Wide Web Consortium, 08 Dec 2009. This version is http://www.w3.org/TR/2009/REC-xml-names-20091208/.
The
latest version is available at http://www.w3.org/TR/xml-names/.