ELEMENTTREE is released under the terms of the Python (MIT style) license:
http://pypi.python.org/pypi/elementtree/

LXML is released under the terms of the BSD license:
http://lxml.de/

PLY is released under the terms of the BSD license:
http://www.dabeaz.com/ply/

mzAPI is part of the multiplerz project and released under 
the terms of the GNU Lesser General Public License:
http://blais.dfci.harvard.edu/index.php?id=63