BCheck</a></li>
  </ul>
<p>The actual format of the EPUB is fairly straightforward. There are a few aspects that are interesting. First, each
    chapter or lesson is actually two different spine items. The main part of the chapter is a reflowable spine item.
    The final page of each chapter is the actual functional WebGL demo. It is a separate spine item which is a fixed-layout
    page where the itemref in the spine has an override. Thus the second chapter's spine items are</p>
<pre>&lt;itemref&#32;idre