How are qualified names mapped to XML namespaces?
If a qualified name in the body of a document (as opposed to the DTD) includes a prefix, then that prefix is used to map the local part of the qualified name to an XML namespace. (Note that the prefix must be in scope — see section 6.) For example, in the following, the prefix foo is used to map the local names A, B, and C to the http://www.foo.