-<!DOCTYPE BOOK PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
+<!DOCTYPE BOOK PUBLIC "-//OASIS//DTD DocBook V4.1//EN" [
<!ENTITY % ug-ent SYSTEM "ug-ent.sgml">
%ug-ent;
<!ENTITY ug-book SYSTEM "ug-book.sgml">
]>
-<Book>
+<Book id="users-guide">
&ug-book;
</Book>