lxml is copyright Infrae and distributed under the BSD license (see
doc/licenses/BSD.txt), with the following exceptions:

Some code, such a selftest.py, selftest2.py and
src/lxml/_elementpath.py are derived from ElementTree and
cElementTree. See doc/licenses/elementtree.txt for the license text.

lxml.cssselect and lxml.html are copyright Ian Bicking and distributed
under the BSD license (see doc/licenses/BSD.txt).

test.py, the test-runner script, is GPL and copyright Shuttleworth
Foundation. See doc/licenses/GPL.txt. It is believed the unchanged
inclusion of test.py to run the unit test suite falls under the
"aggregation" clause of the GPL and thus does not affect the license
of the rest of the package.

The isoschematron implementation uses several XSL and RelaxNG resources:
 * The (XML syntax) RelaxNG schema for schematron, copyright International
   Organization for Standardization (see 
   src/lxml/isoschematron/resources/rng/iso-schematron.rng for the license
   text)
 * The skeleton iso-schematron-xlt1 pure-xslt schematron implementation
   xsl stylesheets, copyright Rick Jelliffe and Academia Sinica Computing
   Center, Taiwan (see the xsl files here for the license text: 
   src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/)
 * The xsd/rng schema schematron extraction xsl transformations are unlicensed
   and copyright the respective authors as noted (see 
   src/lxml/isoschematron/resources/xsl/RNG2Schtrn.xsl and
   src/lxml/isoschematron/resources/xsl/XSD2Schtrn.xsl)