<!ENTITY % local.formal.class "|exercise"> <!ENTITY % docbook.dtd PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN" "http://docbook.org/xml/4.3/docbookx.dtd"> %docbook.dtd; <!ELEMENT exercise %ho; (blockinfo?, (%formalobject.title.content;), (%example.mix;)+) %formal.exclusion;> <!ATTLIST exercise role CDATA #IMPLIED %common.attrib; >