The namespace name is a URI (Uniform Resource Identifier).
URI values can be web address (e.g. http://youdomain.com/...)
web locations: http://yourdomain.com/...
URN (names): urn:...
Or other schemes: scheme:scheme-specific-part
But the processor uses the exact string as the URI value and not URI equivalences:
http://www.somwhere.com/A
http://www.somwhere.com/%41