Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/invalid/P69/ibm69i01.dtd
<!ENTITY ge1 "abcdef"> <!ELEMENT a EMPTY> <!ATTLIST a attr1 CDATA "&ge1;"> <!ENTITY % pe1 "<!ATTLIST a attr2 CDATA #IMPLIED>"> %pe2; <!--* PE reference therebefore doesn't match declaration *-->