Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/not-wf/P63/ibm63n07.dtd
<?xml version="1.0" encoding='UTF-8'?> <!-- DTD for Production 63--> <![IGNORE[ <!ELEMENT animal EMPTY> <!ELEMENT tiger EMPTY> <!--Negative test with pattern5 of P63--> <!--Missing closing sequence -->