[Doitsu]

Originally Posted by tinmug

The OPF does list the to.xhtml inside the guide tags.

As I've aleady pointed out, .opf guide elements are ignored for ePub3 books. You'll need to add a toc landmarks item to the NAV xhtml file. For example:

Spoiler:

    <nav id="landmarks" epub:type="landmarks">
      <h2>Guide</h2>
      <ol>
        <li>
          <a epub:type="cover" href="../Text/cover.xhtml">Cover</a>
        </li>
        <li>
          <a epub:type="bodymatter" href="../Text/chapter1.xhtml">Start reading</a>
        </li>
        <li>
          <a epub:type="toc" href="../Text/nav.xhtml">Table of Contents</a>
        </li>
      </ol>
    </nav>

For a working example book download this ePub3 book from MR. It has the proper NAV xhtml landmarks and compiles OK with KindleGen. If you format your book in the same way the TOC menu item will no longer be greyed out.

Originally Posted by tinmug

Should the lack of the TOC button in Kindle Previewer concern me?

Yes, because it means that the nav xhtml is missing a toc landmarks item; it also means that users of older Kindle models won't be able to access the HTML TOC:

Originally Posted by tinmug

Where should
<item id="toc" properties="nav" href="xhtml/toc.xhtml" media-type="application/xhtml+xml"/>
be placed? In OPF? Inside <guide>?

No, in the nav xhtml file. (See the above example.)

I've replied too quickly that declaration should be in the .opf file.