See:
The prefix xmlns: was specified as a syntactic device
for declaring namespaces, but was not itself associated with any
namespace name by the Jan 1999 namespaces specification. But in some
processing contexts, e.g. DOM, it is useful
to represent all XML attributes as (namespace name, local name)
pairs. For this purpose, the namespace name 
http://www.w3.org/2000/xmlns/ is assigned.
Note that you must use the reserved prefix 
xmlns: when declaring namespaces. It does not work to
declare another prefix with this namespace name and then try to use
it for namespace declarations.
The attribute name xmlns, which is used to declare the
default namespace, is also hereby associated with this namespace
name.
John Cowan and Dan Connolly, for
<br="">
 <a href="/wg_a52b03be97db00a8b00fb8f33a293d141/en/de/www.w3.org/../../XML/Activity#core-wg"="">the W3C XML Core WG</a>
<br="">
 $Revision: 1.7 $ of $Date: 2011/10/28 04:46:37 $ by $Author: liam $