Heading elements for sections within a document. The number associated with each element indicates its relative position in the hierarchy of headings, with 1 indicating the beginning level and 6 the ending level.
<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/2002/06/xhtml2">
<head>
<title>h1, h2, h3, h4, h5, h6</title>
</head>
<body>
<h1> h1 </h1>
<h2> h2 </h2>
<h3> h3 </h3>
<h4> h4 </h4>
<h5> h5 </h5>
<h6> h6 </h6>
</body>
</html>