Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/not-wf/P41/ibm41n03.xml
<?xml version="1.0"?> <!DOCTYPE root [ <!ELEMENT root ANY> <!ATTLIST root attr1 CDATA #IMPLIED> <!ATTLIST root attr2 CDATA #IMPLIED> ]> <root attr1= >missing AttValue in Attribute</root>