Table of Contents | Navigation | EPUB 3 Accessibility Guidelines

Each publication must provide a table of contents in the EPUB navigation document (the toc nav).

The navigation document is one of the two key methods readers use to move around the content, the other being headings. It provides readers easy access to the major sections of the publication, which simplifies quick traversal and random inspection.

The table of contents is constructed using ordered lists (ol). Each list item must either contain a single link (a) to a section of the document, or a link or heading (span) followed by a list of subsections.

If the pronunciation of a link will be ambiguous or incomplete due to embedded images, math content, or other content without intrinsic text, a title attribute must be attached containing an alternate pronunciation.

Examples

Example 1 — Simple links

<nav epub:type="toc" id="toc">
<ol>
  <li>
    <a href="s01.xhtml">A simple link</a>
  </li>
  …
</ol>
</nav>

Example 2 — Nested entries

<nav epub:type="toc" id="toc">
<ol>
  …
  <li>
    <a href="s03.xhtml">A linked heading</a>
    <ol>
      <li><a href="s03-01.xhtml">Subsection</a>
      …
    </ol>
  </li>
  <li>
    <span class="navhd">An unlinked heading</span>
    <ol>
      <li>
        <a href="s04-01.xhtml">Subsection</a>
      </li>
      …
    </ol>
  </li>
  …
</nav>

Example 3 — TOC with hidden branches

<nav epub:type="toc" id="toc">
<ol>
  …
  <li>
    <a href="s05.xhtml">A linked heading</a>
    <ol hidden="hidden">
      <li>
        <a href="s05-01.xhtml">Hidden subsection</a>
      </li>
      …
    </ol>
  </li>
  …
</ol>
</nav>

Example 4 — Ambiguous heading

<nav epub:type="toc" id="toc">
<ol>
  …
  <li>
    <a href="s02.xhtml"
       title="alternate prose title">A simple link 
       requiring an alternate pronunciation</a>
  </li>
  …
</ol>
</nav>

Samples

The EPUB Samples Project contains the following publications that include table of contents navigation:

Simple:
- Moby Dick
Multi-level:
- Accessible EPUB 3
Employing the hidden attribute:
- EPUB 3 Specifications
- Mahabharata

Compliance References and Standards

EPUB 3 — The toc nav Element
HTML5 — The nav element
WCAG 2.0 — G64: Providing a Table of Contents
WCAG 2.0 — G126: Providing a list of links to all other Web pages
WCAG 2.0 — G128: Indicating current location within navigation bars

Additional Resources

EPUB 2 — Declarative Global Navigation — the NCX
Z39.86-2005 — Navigation Control File (NCX)

Frequently Asked Questions

Can I reuse the toc nav as a table of contents in my publication?

Yes, the EPUB navigation document was formulated as an XHTML content document so that it could provide both a declarative table of contents for use by reading systems and also be embeddable as content.

Why does EPUB 3 allow NCX files, and do I need to include one?

The NCX file is allowed for forwards compatibility purposes only. An EPUB 2 reading systems may open an EPUB 3 publication, but it will not be able to use the new navigation document format.

You can ignore the NCX file if your book won't render properly as EPUB 2 content, or if you aren't targeting cross-compatibility.

Your publication may still open on EPUB 2 reading systems even without an NCX. Some reading systems, like Adobe Digital Editions, will not provide navigation by table of contents but will open the publication.

What does the hidden attribute do?

The hidden attribute has no effect on the table of contents when used by a reading system to provide navigation. If you re-use the table of contents in the spine, then it is treated as any other XHTML content document. In these cases, the hidden attribute lets you hide navigation components you don't want rendered, like the page list. It can also be used to hide branches of the table of contents.