Plan 9 from Bell Labs’s /usr/web/sources/contrib/fernan/nhc98/src/libraries/HaXml/tests/xml-conformance/ibm/invalid/P68/ibm68i04.ent
<!ELEMENT a EMPTY> <!ATTLIST a attr1 CDATA "&ge1;"> <!ENTITY ge1 "abcdef"> <!--* GE reference in attr default before declaration *-->