Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/not-wf/P55/ibm55n03.xml
<?xml version="1.0"?> <!-- test invalid syntax for Production 55--> <!DOCTYPE AttrType [ <!ELEMENT AttrType (#PCDATA)> <!ELEMENT a EMPTY> <!ATTLIST a att CData #IMPLIED> ]> <AttrType> Giving a wrong key word of the StringType. </AttrType>