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 let all users locate the same content using page break locators, regardless of whether they use print or digital versions of a publication. This is important to users with disabilities who may transform the information to more easily consume it.

Page numbering has long been a fundamental way to identify and communicate the location of specific parts of published content. Page numbers are used in references, footnotes, endnotes, bibliographies, and tables of content. Particularly, they are critical in academic and learning environments. When participants use the same edition of a printed book, page numbers provide a means to ensure everyone is "on the same page."

Digital publishing, while providing greater access to information, threatens the ability for everyone to locate information by page number. This is because screen size and user preferences can alter content. In one implementation, a screen of content may be considered a page, and the pagination may be updated to match the number of screens of content on a specific device. In another, the page numbering may cease to be used at all in a digital version. In either case, a user whose page numbering no longer matches the printed version cannot easily locate information by page number references.

Digital publishing provides crucial access to content for people who are blind, have low vision, dyslexia or other cognitive disabilities. Such users are likely to adapt content by using a different layout or assistive technology. Providing a mechanism by which users of digital versions can navigate via page numbers, ensures all users can easily reach the same document location.

The scope of this criterion is web content that 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.

Note

In publishing, there can be many different editions of a work, such as 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 which a digital version represents. The page break locaters would be aligned with the specified edition.

Note

Statically paginated formats (such as PDF) where the user agents include a mechanism to navigate by page typically meet this Success Criterion 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.

Note

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 Criterion applies to pages which include elements with the doc-pagebreak semantic role and an associated ID attribute. H99: Provide a page-selection mechanism shows how this can be accomplished. This would not apply to an element which visually shows a page number, unless it also has a recognized role. This Success Criterion is also not concerned with how the web page prints out. Mark up to control output for printing, such as CSS page breaks, is not in scope.

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 a page-selection mechanism

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.
conformance

satisfying all the requirements of a given standard, guideline or specification

mechanism

process or technique for achieving a result

Note

The mechanism may be explicitly provided in the content, or may be relied upon to be provided by either the platform or by user agents, including assistive technologies.

Note

The mechanism needs to meet all success criteria for the conformance level claimed.

page break locators

programmatically determinable destination markers that are arranged in a meaningful sequence to represent a locator serving the same purpose as page breaks in a printed document.

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.
process

series of user actions where each action is required in order to complete an activity

Successful use of a series of Web pages on a shopping site requires users to view alternative products, prices and offers, select products, submit an order, provide shipping information and provide payment information.

An account registration page requires successful completion of a Turing test before the registration form can be accessed.

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.

relied upon

the content would not conform if that technology is turned off or is not supported

technology

mechanism for encoding instructions to be rendered, played or executed by user agents

Note

As used in these guidelines "Web Technology" and the word "technology" (when used alone) both refer to Web Content Technologies.

Note

Web content technologies may include markup languages, data formats, or programming languages that authors may use alone or in combination to create end-user experiences that range from static Web pages to synchronized media presentations to dynamic Web applications.

Some common examples of Web content technologies include HTML, CSS, SVG, PNG, PDF, Flash, and JavaScript.

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.