Adding a <guide> to your OPF file

Apple and Amazon recommend that you specify the types "cover," "toc," and "text," like this:

    <reference type="cover" title="Cover Image" href="cover.xhtml"></reference>
    <reference type="toc" title="Table of Contents" href="toc.xhtml"></reference>
    <reference type="text" title="Startup Page" href="chapter1.xhtml"></reference>

Amazon recommends only using those three types, so if you are preparing your file for Amazon, those are all you'll need.

The EPUB 2 spec mentions the following types: