Understanding Success Criterion 2.4.13: Page Break Navigation

Success Criterion 2.4.13 Page Break Navigation (Level A): For web content with page break locators, a mechanism is available to navigate to each locator.

Status

This understanding document is part of the draft WCAG 2.2 content. It may change or be removed before the final WCAG 2.2 is published.

Intent

The purpose of this success criterion is to allow people using assistive technology to find references to content based on the page break locators found in the default view or printed version of a publication.

Page numbering has long been a fundamental way to identify and communicate the location of written content. Page numbers are used constantly in references, footnotes, endnotes, and bibliographies. Particularly, they are critical in academic and learning environments.

Digital publishing has provided valuable access to content for people who are blind, have low vision, dyslexia or other cognitive disabilities. In order to consume the information the content may be adapted to use a different layout, or presented to them using assistive technology. If there is no clear way to find a specific page from the print version that was referenced by a professor in class, because the electronic version is zoomed-in and that paragraph is on page 145 of the user's version of the content, the user misses out on valuable and sometimes critical information to understanding the reference.

The scope of this criterion is web content which is part of a Web page. EPUB can fulfill this definition if it is available to read at a URI. The more common case that is in scope is an EPUB book converted to be read by a web browser.

In publishing, there can be many different editions of a work, e.g. a second edition or a paperback edition. There is a requirement (separate from accessibility) for metadata in digital publications like EPUB to identify the edition of the title of which this digital version represents. The page break locaters would be aligned with the specified edition.

Note

Statically paginated formats (e.g., PDF) where the user agents include a mechanism to navigate by page typically meet this success criteria by default. The user agents for the EPUB format also typically provide the navigation mechanism if a page list is included. Web browsers do not have a standard page navigation mechanism, so for HTML content with page break locators it is the author responsibility to add that mechanism.

For a Page Break Locator to be a "programmatically determinable destination marker", it needs to have a role that identifies it as a page break, and a method of determining which page in a sequence it represents. This would not apply to an element which visually shows a page number, unless it also has a recognized role. H99: Provide page list navigation provides an example of a page break locator.

Benefits

Examples

Related Resources

Resources are for information purposes only, no endorsement implied.

Techniques

Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this Success Criterion. However, it is not necessary to use these particular techniques. For information on using other techniques, see Understanding Techniques for WCAG Success Criteria, particularly the "Other Techniques" section.

Sufficient Techniques

  1. H99: Provide page list navigation

Key Terms

assistive technology

hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents

Note

functionality provided by assistive technology includes alternative presentations (e.g., as synthesized speech or magnified content), alternative input methods (e.g., voice), additional navigation or orientation mechanisms, and content transformations (e.g., to make tables more accessible).

Note

Assistive technologies often communicate data and messages with mainstream user agents by using and monitoring APIs.

Note

The distinction between mainstream user agents and assistive technologies is not absolute. Many mainstream user agents provide some features to assist individuals with disabilities. The basic difference is that mainstream user agents target broad and diverse audiences that usually include people with and without disabilities. Assistive technologies target narrowly defined populations of users with specific disabilities. The assistance provided by an assistive technology is more specific and appropriate to the needs of its target users. The mainstream user agent may provide important functionality to assistive technologies like retrieving Web content from program objects or parsing markup into identifiable bundles.

Assistive technologies that are important in the context of this document include the following:

  • screen magnifiers, and other visual reading assistants, which are used by people with visual, perceptual and physical print disabilities to change text font, size, spacing, color, synchronization with speech, etc. in order to improve the visual readability of rendered text and images;
  • screen readers, which are used by people who are blind to read textual information through synthesized speech or braille;
  • text-to-speech software, which is used by some people with cognitive, language, and learning disabilities to convert text into synthetic speech;
  • speech recognition software, which may be used by people who have some physical disabilities;
  • alternative keyboards, which are used by people with certain physical disabilities to simulate the keyboard (including alternate keyboards that use head pointers, single switches, sip/puff and other special input devices.);
  • alternative pointing devices, which are used by people with certain physical disabilities to simulate mouse pointing and button activations.
page break locators

programmatically determinable destination markers that are arranged in a meaningful sequence to determine the location of a page in relation to others in the set.

Examples would be:

  • A digital version of an ebook that has a print version, it includes the page break locators to align with the print edition.
  • A digital book is published with no print equivalent and page break locators are inserted which supports direct navigation across platforms and form factors.
programmatically determined

determined by software from author-supplied data provided in a way that different user agents, including assistive technologies, can extract and present this information to users in different modalities

Note

Determined in a markup language from elements and attributes that are accessed directly by commonly available assistive technology.

Note

Determined from technology-specific data structures in a non-markup language and exposed to assistive technology via an accessibility API that is supported by commonly available assistive technology.

user agent

any software that retrieves and presents Web content for users

Web browsers, media players, plug-ins, and other programs — including assistive technologies — that help in retrieving, rendering, and interacting with Web content.

web page

a non-embedded resource obtained from a single URI using HTTP plus any other resources that are used in the rendering or intended to be rendered together with it by a user agent

Note

Although any "other resources" would be rendered together with the primary resource, they would not necessarily be rendered simultaneously with each other.

Note

For the purposes of conformance with these guidelines, a resource must be "non-embedded" within the scope of conformance to be considered a Web page.

A Web resource including all embedded images and media.

A Web mail program built using Asynchronous JavaScript and XML (AJAX). The program lives entirely at http://example.com/mail, but includes an inbox, a contacts area and a calendar. Links or buttons are provided that cause the inbox, contacts, or calendar to display, but do not change the URI of the page as a whole.

A customizable portal site, where users can choose content to display from a set of different content modules.

When you enter "http://shopping.example.com/" in your browser, you enter a movie-like interactive shopping environment where you visually move around in a store dragging products off of the shelves around you and into a visual shopping cart in front of you. Clicking on a product causes it to be demonstrated with a specification sheet floating alongside. This might be a single-page Web site or just one page within a Web site.