fixed a small error, daniel
diff --git a/doc/xmldtd.html b/doc/xmldtd.html
index 0dcdca1..7a2be68 100644
--- a/doc/xmldtd.html
+++ b/doc/xmldtd.html
@@ -158,7 +158,7 @@
in this order. The declaration of one element of the structure and its
content are done in a single declaration. Similary the following declares
<code>div1</code> elements:</p>
-<p><code><!ELEMENT div1 (head, (p | list | note)*, div2*)></code></p>
+<p><code><!ELEMENT div1 (head, (p | list | note)*, div2?)></code></p>
<p>means div1 contains one <code>head</code> then a series of optional
<code>p</code>, <code>list</code>s and <code>note</code>s and then an
optional <code>div2</code>. And last but not least an element can contain