Qualebook

Qualebook

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Rule #79

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The ebook includes a compliant EPUB navigation document (nav.xhtml).

The EPUB navigation document (nav.xhtml) is a specialized XHTML file that provides essential navigation features, such as the Table of Contents (ToC), allowing users to navigate content quickly and easily. This document must comply with EPUB 3.3 specifications and include at least one structured Table of Contents.

Objectives

  • Ensure efficient and intuitive navigation throughout the ebook.
  • Allow assistive technologies to present a clear navigation structure.
  • Improve content accessibility for people with disabilities.
  • Facilitate discovery and quick access to various sections of the book.
  • Ensure interoperability with all EPUB 3-compliant reading systems.

Implementation

  • Create a file named nav.xhtml within the EPUB content folder.
  • Declare this file in the OPF package manifest using the properties="nav" attribute.
  • Include at least one <nav epub:type="toc"> element containing the main Table of Contents.
  • Structure the Table of Contents using an <ol> (ordered list) element with <li> elements for each entry.
  • Use <a> links pointing to the corresponding sections of the book.
  • Add a heading to the navigation (e.g., <h1>Table of Contents</h1>).
  • Enable hierarchical entries by nesting <ol> lists for sub-sections.
  • Optionally, add other navigation types: <nav epub:type="landmarks"> for landmarks, <nav epub:type="page-list"> for the page list, <nav epub:type="loi"> for the list of illustrations, or <nav epub:type="lot"> for the list of tables.
  • Consider adding epub:type="frontmatter" to the <body> element of the navigation document.

Control

  • Test navigation in various reading systems. Verify that all Table of Contents links work correctly and point to the intended sections.
  • Check that the heading hierarchy in the Table of Contents accurately reflects the book’s structure.
  • Verify that the order of entries in the Table of Contents matches the logical reading order of the book.

Validation

  • Reported by epubcheck.
  • Reported by Ace by DAISY.
  • Needs to be verified by a human.