strange treatment of namespaces in RDF/XML

From http://www.w3.org/TR/rdf-syntax-grammar/, Section 5.1

	Within RDF/XML documents it is not permitted to use XML namespaces
	whose namespace URI is either:
	- the RDF Namespace URI Reference concatenated with additional
 	  characters or 
	- the XML Namespace URI Reference concatenated with additional
	  characters. 


So
	... xmlns:xm = "http://www.w3.org/XML/1998/namesp"
	... rdf:about="ace#hi" ...
is legal, as is
	... xmlns:xmx = "http://www.w3.org/XML/1998/namespace"
	... rdf:about="#hi" ...
but 
	... xmlns:xmxx = "http://www.w3.org/XML/1998/namespace#h"
	... rdf:about="i" ...
is not. 

Also, 
	... xmlns:rd = "http://www.w3.org/1999/02/22-rdf-syntax-n"
	... rdf:about="s#hi" ...
is legal, as is
	... xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
	... rdf:about="hi" ...
but 
	... xmlns:rdx = "http://www.w3.org/1999/02/22-rdf-syntax-ns#h"
	... rdf:about="i" ...
is not. 

Weird.


Is this desirable behaviour?

Peter F. Patel-Schneider
Bell Labs Research
Lucent Technologies