Cannot parse MathML dtd...

[David Adam <david@quercus.org>]

Greetings!
  I am trying to get MathML added in to DocBook, and am stymied - I 
cannot get the DTD to parse, after (I think) following all the 
suggestions I could find.  The errant code is:

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd";
[
<!ENTITY % MATHML.prefixed "INCLUDE">
<!ENTITY % MATHML.prefix "mml">
<!ENTITY % equation.content "(alt?,
(graphic+|mediaobject+|mml:math))">
<!ENTITY % inlineequation.content "(alt?,
(graphic+|inlinemediaobject+|mml:math))">
<!ENTITY % mathml2-qname-1 PUBLIC "-//W3C//ENTITIES MathML 2.0 Qualified 
Names 1.0//EN"
"/usr/share/sgml/docbook/MathML-1.0/mathml2-qname-1.mod">
%mathml2-qname-1;
<!ENTITY % mathml PUBLIC "-//W3C//DTD MathML 2.0//EN"
"/usr/share/sgml/docbook/MathML-1.0/mathml2.dtd">
%mathml;
]>
<article>
</article>

and the Emacs parser comes up with

/usr/share/sgml/docbook/MathML-1.0/mathml2-qname-1.mod line 1 col 3 
entity mi.qname
/usr/share/sgml/docbook/MathML-1.0/mathml2.dtd line 273 col 20 entity mathml
/home/david/IceAges2/testfile.xml line 16 col 8
Name expected; at: :mi

Parsing with nsgmls comes up with a long list of complaints about the 
colon (:) being an illegal character.  The mathml2.dtd has a single 
attribute named "xlink:href" (without the quotes) that looks like it may 
be related to the problem, but changing the colon to a period or a 
hyphen did not seem to make a difference.

Any insights as to what I am doing wrong will be gratefully accepted.  
And thank you all!

david adam