Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/not-wf/P64/ibm64n02.xml
<?xml version="1.0"?> <!-- syntax test for Production 64--> <!DOCTYPE animal SYSTEM "ibm64n02.dtd" [ <!ELEMENT animal ANY> ]> <animal> Negative Test. Pattern3. Missing closing sequence. </animal>