Elements and DTD:s
Fredrik Lundh | March 2005
ElementTree has limited support for DTD:s. As of 1.2.6, you can use internal DTD:s to define entities, but external DTD:s are not supported. Validation is not supported in either case.
If you need more DTD support, you can use an alternative parser. Here’s an example: The ElementRXP Module (dead link).