Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/invalid/P69/ibm69i02.xml
<?xml version="1.0"?> <!DOCTYPE root SYSTEM "ibm69i02.dtd" [ <!ELEMENT root (#PCDATA|a)* > ]> <root> pcdata content <a attr1="xyz"/> </root> <!--* a invalid test for P69 VC:Entity Declared *-->