Summary: Explains how to include more than one XML language within the same document.
<!DOCTYPE document PUBLIC "-//CNX//DTD CNXML 0.5//EN"
"http://cnx.rice.edu/cnxml/0.5/DTD/cnxml_plain.dtd">
<!DOCTYPE document PUBLIC "-//CNX//DTD CNXML 0.5 plus MathML//EN"
"http://cnx.rice.edu/cnxml/0.5/DTD/cnxml_mathml.dtd">
<!DOCTYPE document PUBLIC "-//CNX//DTD CNXML 0.5 plus QML//EN"
"http://cnx.rice.edu/cnxml/0.5/DTD/cnxml_qml.dtd">
<!DOCTYPE document PUBLIC "-//CNX//DTD CNXML 0.5 plus
MathML plus QML//EN"
"http://cnx.rice.edu/cnxml/0.5/DTD/cnxml_mathml_qml.dtd">