the namespace should be unique anywhere and 
anytime. The URI is also globally unique, but its namespace is a temporal 
setting for the URI abbreviation in the scope of a RDF/XML file or a Web page. 
In a RDF/XML file, a settled namespace for a URI is scoped within the file, and 
it is legal that someone set a different name of namespace for the identical URI 
in another RDF/XML file. Thus, in ideal the two files should be correctly merged 
regardless of namespaces but regarding URIs. For example, if you ha