<html>
<title>Example of DTD in HTML</title>
<body>
<pre>
<!-- Example DTD
blah
blah
blah
blah
blah
blah
blah
blah -->
<a name="gi-a" /><!-- Element a is the top-level element -->
<!ELEMENT a ( <a href="#gi-b">b</a> )>
<!--CONTENTS: blah -->
<!--USAGE: blah -->
<!--ALLOWABLE VALUES: blah -->
<!--EXAMPLE: blah -->
<!--
blah
blah
blah
blah -->
<a name="gi-b" /><!-- Element b is the bottom element -->
<!ELEMENT b (<a href="#xml-pcdata">#PCDATA</a> )>
<!--CONTENTS: blah -->
<!--USAGE: blah -->
<!--ALLOWABLE VALUES: blah -->
<!--EXAMPLE: blah -->
<!--
blah
blah
blah
blah -->
<!ATTLIST <a href="#gi-a">a</a>
id <a href="#xml-id">ID</a> #REQUIRED >
<!--CONTENTS: blah -->
<!--USAGE: blah -->
<!--ALLOWABLE VALUES: blah -->
<!--EXAMPLE: blah -->
<!--
blah
blah
blah
blah -->
<a name="xml-id" /><!-- ID attributes must be unique -->
<a name="xml-pcdata" /><!-- #PCDATA means that this element can have data (text), PIs, entity
and character references, but no sub-elements -->
<!--
blah
blah
blah
blah
blah
blah
blah
blah -->
<!--
blah
blah
blah
blah
blah
blah
blah
blah -->
</pre>
</html>