NS.prefixed ... MATHML.prefixed ...?

IIRC, there is some kind of slight of hand going on in the following DTD 
snippet taken from the 
http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd

<!-- tell the MathML DTD to do the right prefixing -->
<!ENTITY % NS.prefixed     "INCLUDE">
<!ENTITY % MATHML.prefix   "%mathml-prefix;">
<!ENTITY % NamespaceDecl.attrib "
	xmlns%mathml-colon;%mathml-prefix;
	CDATA	#FIXED 'http://www.w3.org/1998/Math/MathML'
">

Would someone please explain to me what these declarations accomplish?

Steven