Web Content Accessibility Guidelines 2.0 -- Document 1 - Core Required Only

W3C Working Draft 28 July 2003

This version:
Latest version:
Ben Caldwell, Trace R&D Center
Wendy Chisholm, W3C
Gregg Vanderheiden, Trace R&D Center
Jason White, University of Melbourne


This draft includes a number or editorial changes, recent proposals and an additional level of conformance.


W3C published the Web Content Accessibility Guidelines 1.0 (WCAG 1.0) as a Recommendation in May 1999. This Working Draft for version 2.0 builds on WCAG 1.0. It has the same aim: to explain how to make Web content accessible to people with disabilities and to define target levels of accessibility. Incorporating feedback on WCAG 1.0, this Working Draft of version 2.0 focuses on checkpoints. It attempts to apply checkpoints to a wider range of technologies and to use wording that may be understood by a more varied audience.

Status of this Document

This document is an editors' copy that has no official standing.

This document is prepared by the Web Content Accessibility Guidelines Working Group (WCAG WG) to show how more generalized (less HTML-specific) WCAG checkpoints might read. This draft is not yet based on consensus of the WCAG Working Group nor has it gone through W3C process. This Working Draft in no way supersedes WCAG 1.0.

Please refer to "Issue Tracking for WCAG 2.0 Working Draft" for a list of open issues related to this Working Draft. The "History of Changes to WCAG 2.0 Working Drafts" is also available.

This is a draft document and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use W3C Working Drafts as reference material or to cite them as other than "work in progress". A list of current W3C Recommendations and other technical documents is available.

The Working Group welcomes comments on this document at public-comments-wcag20@w3.org. The archives for this list are publicly available. Archives of the WCAG WG mailing list discussions are also publicly available.

Patent disclosures relevant to this specification may be found on the WCAG Working Group's patent disclosure page in conformance with W3C policy.

This document has been produced as part of the W3C Web Accessibility Initiative (WAI). The goals of the WCAG WG are discussed in the Working Group charter. The WCAG WG is part of the WAI Technical Activity.

Table of Contents

Guideline 1: PERCEIVABLE. Make Content Perceivable by Any User

1.1 [CORE] All non-text content that can be expressed in words has a text equivalent of the function or information that the non-text content was intended to convey. [was 1.1]

Required Success Criteria for Checkpoint 1.1
  1. non-text content that can be expressed in words has a text-equivalent explicitly associated with it.

    • The text equivalent fulfills the same function as the author intended for the non-text content (i.e. it presents all of the intended information and/or achieves the same function of the non-text content). [I#332]

  2. non-text content that can not be expressed in words has a descriptive label provided as its text-equivalent.

1.2 [CORE] Synchronized media equivalents are provided for time-dependent presentations. [was 1.2]

Editorial Note (06/10/03): There is discussion about moving some of the current success criteria from Required to Best Practice or to an Extended checkpoint. The issue stems from trying to apply the success criteria to every Web cam, newscast, and home broadcast. Another approach is to allow a conformance claim to state, for example, "All pages and applications on this site meet the Core checkpoints of WCAG 2.0 except the Web cam at http://example.org/webcam/."

Required Success Criteria for Checkpoint 1.2
  1. an audio description is provided of all significant visual information in scenes, actions, and events that cannot be perceived from the sound track alone to the extent possible given the constraints posed by the existing audio track and limitations on freezing the audio visual program to insert additional auditory description.


    When adding audio description to existing materials, the amount of information conveyed through audio description is constrained by the amount of space available in the existing audio track unless the audio/video program is periodically frozen to insert audio description. However, it is often impossible or inappropriate to freeze the audio/visual program to insert additional audio description.

  2. all significant dialogue and sounds are captioned

  3. descriptions and captions are synchronized with the events they represent.

  4. if the Web content is real-time video with audio, real-time captions are provided unless the content:

    • is a music program that is primarily non-vocal

  5. if the Web content is real-time non-interactive video (e.g., a Webcam of ambient conditions), either provide an equivalent that conforms to checkpoint 1.1 (e.g., an ongoing update of weather conditions) or link to an equivalent that conforms to checkpoint 1.1 (e.g., a link to a weather Web site).

  6. if a pure audio or pure video presentation requires a user to respond interactively at specific times in the presentation, then a time-synchronized equivalent (audio, visual or text) presentation is provided.

1.3 [CORE] Information, functionality, and structure are separable from presentation. [was 1.3] [I#336]

Required Success Criteria for Checkpoint 1.3
  1. the following can be derived programmatically (i.e. through a markup or data model that is assistive technology compatible) from the content without requiring user interpretation of presentation. [I#337]

    1. any hierarchical elements and relationships, such as headings, paragraphs and lists

    2. any non-hierarchical relationships between elements such as cross-references and linkages, associations between labels and controls, associations between cells and their headers, etc.

    3. any emphasis

  2. any information presented using color is also available without color (e.g. through context or markup). [I#317]

1.4 [CORE] All characters and words in the content can be unambiguously decoded. [was 1.6] 

Required Success Criteria for Checkpoint 1.4
  1. text in the content is provided in Unicode or sufficient information is provided so that it can be automatically mapped back to Unicode.

Guideline 2: OPERABLE. Ensure that Interface Elements in the Content are Operable by Any User

2.1 [CORE] All functionality is operable at a minimum through a keyboard or a keyboard interface. [was 2.1]

Required Success Criteria for Checkpoint 2.1
  1. all of the functionality of the content, where the functionality or its outcome can be expressed concisely in words, is operable at a minimum through a keyboard or keyboard interface.


    refer to checkpoint 4.3 for information regarding user agent support.

2.2 [CORE] Users can control any time limits on their reading, interaction, or responses unless control is not possible due to nature of real time events or competition. [was 2.2]

Required Success Criteria for Checkpoint 2.2
  1. at least one of the following is true for each time limit:

    • the user is allowed to deactivate the time limits,

    • or the user is allowed to adjust the time limit over a wide range which is at least ten times or default setting or average user's preference,[I#347]

    • or the user is warned before time expires and given at least 10 seconds to extend the time limit,

    • or the time limit is due to a real-time event (e.g. auction) and no alternative to the time limit is possible,

    • or the time limit is part of a competitive activity where timing is an essential part of the activity (e.g. competitive gaming or time based testing).

2.3 [CORE] User can avoid experiencing screen flicker. [was 2.3]

Editorial Note (06/10/03): This Checkpoint is currently included in the Core set of Checkpoints because the WCAG WG expects that it will be possible to test content for flicker and the result will be a flicker rate in Hz that can be stored in a machine-readable format. The WG also expects that a user could, in the future, be able to configure a client to only render content that flickers at "a rate greater than X" by which the client could compare the content metadata and the user's preference. If the assumption regarding a testing tool does not hold at time of final review of these guidelines, this checkpoint will be moved to the Extended set of Checkpoints."

Required Success Criteria for Checkpoint 2.3
  1. At least one of the following is true:

    1. content was not designed to flicker (or flash) in the range of 3 to 49 Hz.

    2. if flicker is unavoidable, the user is warned of the flicker before they go to the page, and as close a version of the content as is possible without flicker is provided.

    Editorial Note:  We would like to include a third criteria here that would state that a test that was conducted and the pages passed. No test or tool exists yet though. We're looking into how such a test and/or tool might be designed.

Guideline 3: UNDERSTANDABLE. Make content and controls understandable to as many users as possible.

3.1 [CORE] Language of content can be programmatically determined.[was 1.6 partial]  

Required Success Criteria for Checkpoint 3.1
  1. passages or fragments of text occurring within the content that are written in a language other than the primary natural language of the content as a whole, are identified, including specification of the language of the passage or fragment.


    Foreign words or phrases that are found in standard unabridged dictionaries for the natural language of the content do not need to be marked. (For a list of common examples of exceptions for different languages, see the W3C-WAI foreign word exception examples listing at [@@ insert URL].)[I#324]

Guideline 4: ROBUST. Use Web technologies that maximize the ability of the content to work with current and future accessibility technologies and user agents.

4.1 [CORE] Technologies are used according to specification [was 5.1]

Required Success Criteria for Checkpoint 4.1
  1. for markup, except where the site has documented that a specification was violated for backward compatibility, the markup has:

    1. passed validity tests of the language (whether it be conforming to a schema, Document Type Definition (DTD), or other tests described in the specification)

    2. structural elements and attributes are used as defined in the specification

    3. accessibility features are used

    4. deprecated features are avoided[I#329]

    Editorial Note: The following two success criteria seem to overlap with checkpoint 4.3. There is an open question about whether they should be deleted since checkpoint 4.3 covers programmatic interfaces.

  2. for Application Programming Interfaces (API's), programming standards for the language are followed.

  3. accessibility features and API's are used when available.