EPUB navigation document, NCX and guide

An EPUB 3 book has a navigation document: an XHTML file, marked in the manifest with properties="nav", that holds the table of contents and optional lists of pages and landmarks. EPUB 2 used an NCX file instead, and marked landmarks in the package’s guide. Many EPUB 3 books include an NCX and a guide as well, for older reading systems, which EPUB 3 readers ignore.

The navigation document

An ordinary XHTML content document with one or more nav elements, each given a role by epub:type (namespace http://www.idpf.org/2007/ops). It may also be in the spine and be read like any other page.

`epub:type`	Number	Content
`toc`	Exactly 1	The table of contents, in reading order.
`page-list`	At most 1	Links to the page break markers that match a print edition’s pages, labelled with the page numbers.
`landmarks`	At most 1	Links to key places; each `a` carries an `epub:type` naming the place: see landmarks.
other values	Any	Further lists, such as `loi` (illustrations), `lot` (tables), `loa` (audio), `lov` (video).

Each nav has this shape:

An optional heading (h1 to h6, or hgroup).
Exactly one ol.
Each li holds an a (a link with a non-empty label) or a span (a heading with no link of its own), optionally followed by a nested ol. A span must be followed by a nested ol.
Links point to content documents in the spine, or fragments of them.
The hidden attribute hides a nav or part of one from display when the document is read in the spine; reading systems still use it for navigation.

<nav epub:type="toc" id="toc">
  <h1>Contents</h1>
  <ol>
    <li><a href="chapter1.xhtml">I. Introduction</a></li>
    <li><span>Part Two</span>
      <ol>
        <li><a href="chapter2.xhtml#s1">II. The Machine</a></li>
      </ol>
    </li>
  </ol>
</nav>
<nav epub:type="landmarks" hidden="">
  <ol>
    <li><a epub:type="toc" href="nav.xhtml#toc">Contents</a></li>
    <li><a epub:type="bodymatter" href="chapter1.xhtml">Start</a></li>
  </ol>
</nav>

Landmarks

Landmark links take their epub:type from the structural semantics vocabulary. Reading systems act mostly on these:

`epub:type`	Place
`cover`	The cover page.
`titlepage`	The title page.
`frontmatter`	The start of the front matter.
`bodymatter`	Where the main text starts; many readers open a new book here.
`backmatter`	The start of the back matter.
`toc`	The table of contents.
`loi`, `lot`	Lists of illustrations and tables.
`preface`, `bibliography`, `glossary`, `index`, `appendix`	Those sections.

The NCX (EPUB 2)

The Navigation Control file for XML, taken from the DAISY digital talking book standard (ANSI/NISO Z39.86-2005). It is XML in the namespace http://www.daisy.org/z3986/2005/ncx/, version="2005-1", usually named toc.ncx, with media type application/x-dtbncx+xml; the spine’s toc attribute names it.

Element	Attributes	Content
`ncx`	`version`, `xml:lang`	`head`, `docTitle`, `docAuthor` (any), `navMap`, `pageList` (optional), `navList` (any).
`head`		`meta` elements with `name` and `content`: see below.
`docTitle`, `docAuthor`		A `text` element, and optionally `audio` and `img`.
`navMap`		Optional `navInfo` and `navLabel`, then one or more `navPoint`.
`navPoint`	`id` (required), `playOrder`, `class`	`navLabel` (one or more), `content`, then nested `navPoint` elements. `playOrder` numbers all navigation points, page targets and nav targets together in reading order, from 1.
`navLabel`	`xml:lang`, `dir`	`text`, and optionally `audio` and `img`.
`content`	`src` (required), `id`	Empty. The target, as a file and optional fragment.
`pageList`	`id`, `class`	Optional `navInfo` and `navLabel`, then `pageTarget` elements.
`pageTarget`	`id`, `value`, `type` (`front`, `normal` or `special`), `playOrder`, `class`	`navLabel` and `content`: one printed page.
`navList`	`id`, `class`	`navInfo`, `navLabel` and `navTarget` elements: a list of things such as illustrations.
`navTarget`	`id`, `value`, `playOrder`, `class`	`navLabel` and `content`.
`text`		The label text.
`audio`	`src`, `clipBegin`, `clipEnd`	An audio label, in DAISY books.
`img`	`src`	An image label.

`meta name`	Content
`dtb:uid`	The book’s unique identifier; should match the package’s.
`dtb:depth`	The deepest nesting of `navPoint`s, from 1.
`dtb:totalPageCount`	The number of pages in `pageList`, or 0.
`dtb:maxPageNumber`	The highest page number, or 0.
`dtb:generator`	Optional: the program that made it.

The guide

In the package document, guide holds reference elements, each with type (required), title and href (required). OPF 2.0.1 defines these types; others must start with other., as in other.afterword.

Type	Place	Type	Place
`cover`	the book cover	`dedication`	dedication
`title-page`	page with title, author, publisher	`epigraph`	epigraph
`toc`	table of contents	`foreword`	foreword
`index`	back-of-book index	`loi`	list of illustrations
`glossary`	glossary	`lot`	list of tables
`acknowledgements`	acknowledgements	`notes`	notes
`bibliography`	bibliography	`preface`	preface
`colophon`	colophon	`text`	first “real” page of content
`copyright-page`	copyright page

.EPUB File Format – Navigation, NCX and guide

The navigation document

Landmarks

The NCX (EPUB 2)

The guide