xmlns

Namespace for XML-based tags.

Browser/User Agent Support

IE Netscape Mozilla Opera Safari
2.0+ 1.0+ 1.0+ 4.0+ 1.0+

IE	Netscape	Mozilla	Opera	Safari
2.0+	1.0+	1.0+	4.0+	1.0+

http://www.w3.org/1999/xhtml Default value.