Problem with ws-addr-metadata.xsd

Someone I'm working with noticed an odd issue with the schema at the  
following URL:  
<http://www.w3.org/2007/05/addressing/metadata/ws-addr-metadata.xsd>. There  
is a bare reference to "wsp:Policy" without any specification of the  
namespace for the "wsp" prefix. Convention is convention, but assuming the  
WS-Policy namespace is not valid.