http://www.hxa.name/articles/content...7241_2007.html
Code:
<navPoint id="file01" playOrder="1">
<navLabel>
<text>Text for top level</text>
</navLabel>
<content src="file01.xhtml"/>
<navPoint id="file02" playOrder="2">
<navLabel>
<text>text for first second level</text>
</navLabel>
<content src="file02.xhtml"/>
</navPoint>
(more second level)
</navPoint>
Code:
Also in head portion
<meta name="dtb:depth" content="2"/>
note content = 2