Allow Set to be recursive

diff --git a/docbook/xml/dbhierx.mod b/docbook/xml/dbhierx.mod
index 5b15d635349140b386cd0c32e8a754c434df4d8f..10edd3b897d32b9548c00b00a4a3bc136748ca97 100644 (file)
--- a/docbook/xml/dbhierx.mod
+++ b/docbook/xml/dbhierx.mod
@@ -209,7 +209,7 @@
 
 <!ENTITY % set.element "INCLUDE">
 <![%set.element;[
-<!ELEMENT set %ho; ((%div.title.content;)?, setinfo?, toc?, (%book.class;)+,
+<!ELEMENT set %ho; ((%div.title.content;)?, setinfo?, toc?, (set|%book.class;)+,
                setindex?)
                %ubiq.inclusion;>
 <!--end of set.element-->]]>