Web Content Accessibility Guidelines 2.0 -- Document 2 - Extended (testable)

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

Core Checkpoints for Guideline 1

1.1e [Extended Checkpoint for 1.1] 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]

Success Criteria for Extended Checkpoint 1.1e
  1. All Core Success Criteria for this checkpoint have been met (link to 1.1 in Core)

  2. non-text content that can not be expressed in words has a text equivalent for all aspects that can be expressed in words.

1.2e [Extended Checkpoint for 1.2] 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/."

Success Criteria for Extended Checkpoint 1.2e
  1. All Core Success Criteria for this checkpoint have been met (link to 1.2 in Core)

  2. Editorial Note: This whole Checkpoint (1.2) needs reworking. Perhaps move some down from above, or limit the items above to just certain classes of content - and then put the rest of the coverage (for other types of content) here.

1.3e [Extended Checkpoint for 1.3] Information, functionality, and structure are separable from presentation. [was 1.3] [I#336]

Success Criteria for Extended Checkpoint 1.3e
  1. All Core Success Criteria for this checkpoint have been met (link to 1.3 in Core)

  2. any information presented using color is also available without color and without having to interpret markup.[I#317]

1.4e [Extended Checkpoint for 1.4] All characters and words in the content can be unambiguously decoded. [was 1.6] 

Success Criteria for Extended Checkpoint 1.4e
  1. All Core Success Criteria for this checkpoint have been met (link to 1.4 in Core)

  2. abbreviations and acronyms are clearly identified each time they occur if they collide with a word in the standard language that would also logically appear in the same case (e.g. all caps). (See also checkpoint 3.1) [I#341]

  3. symbols such as diacritic marks that are found in standard usage of the natural language of the content, and that are necessary for unambiguous identification of words, are present or another standard mechanism for disambiguation is provided.

Extended Checkpoints for Guideline 1

1.5 [E1] Structure has been made perceivable to more people through presentation(s), positioning, and labels. [was 1.4]

Success Criteria for Checkpoint 1.5
  1. the structural elements present have a different visual appearance or auditory characteristic from each other and from body text.

  2. the structural emphases are chosen to be distinct on different major visual display types (e.g. black and white, small display, mono audio playback).

  3. content is constructed such that users can control the presentation of the structural elements.

1.6 [E2] Foreground content is easily differentiable from background for both auditory and visual default presentations. [was 1.5]

Success Criteria for Checkpoint 1.6
  1. text content that is presented over a background image or pattern is implemented using mechanisms that allow the user to display the text without the background image or pattern.

  2. text that is presented over a background color or grayscale has a mechanism that allows the text to be presented in a fashion that has a contrast greater than ______ between text and background color as measured by ______.[I#344]

  3. when text content is presented over a background image or pattern, the text is easily readable when the page is viewed in 256 grayscale.

  4. text content is not presented over a background image or pattern OR the text is easily readable when the page is viewed in black and white (no grayscale).

  5. this item should read identically to the required item #2, except that it should say "in default presentation mode"[I#345]

  6. audio content does not contain background sounds OR the background sounds are at least 20 db lower than the foreground audio content.


A 20 db difference in sound level is roughly 4 times quieter (or louder).

Editorial Note: The working group is seeking an algorithm that measures contrast in a way that is accurate and testable enough that we could include it in the guidelines. One algorithm, which comes from the Techniques For Accessibility Evaluation And Repair Tools document, is currently under consideration for inclusion in the techniques, but the group has not yet found something that is specific enough to be included at the guidelines level.

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

Core Checkpoints for Guideline 2

2.1e [Extended Checkpoint for 2.1] All functionality is operable at a minimum through a keyboard or a keyboard interface. [was 2.1]

Success Criteria for Extended Checkpoint 2.1e
  1. All Core Success Criteria for this checkpoint have been met (link to 2.1 in Core)

  2. wherever a choice between event handlers is available and supported, the more abstract event is used.

2.2e [Extended Checkpoint for 2.2] 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]

Success Criteria for Extended Checkpoint 2.2e
  1. All Core Success Criteria for this checkpoint have been met (link to 2.2 in Core)

  2. wherever possible, activities are designed so that time limits are not an essential part of the activity.  (e.g. alternate forms of competition, testing, etc. are used that are not time based.)

  3. any blinking content can be turned off.[I#325]

  4. any moving content can be frozen using the keyboard[I#325]

2.3e [Extended Checkpoint for 2.3] 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."

Success Criteria for Extended Checkpoint 2.3e
  1. All Core Success Criteria for this checkpoint have been met (link to 2.3in Core)
  2. animation or other content does not visibly or purposely flicker between 3 and 49 Hz.

  3. content that might create a problem has been tested [using XYZ tool]; only pages with unavoidable flicker remain and appropriate warnings along with a close alternative presentation have been provided for these pages.

  4. (tougher test - that would make pages pass with even slower equipment. Hardware might be old or just slow for other reasons.) [I#321]

Extended Checkpoints for Guideline 2

2.4 [E3] Structure and/or alternate navigation mechanisms have been added to facilitate orientation and movement in content. [was 3.1 and 3.2]

Success Criteria for Checkpoint 2.4
  1. In documents greater than 50,000 words or sites larger than 50 perceived pages, the following are provided.

    1. hierarchical structure mark up

    2. Table of contents (or site map)

    3. Alternate display orders (or alternate site navigation mechanisms)

  2. Users are able to skip over large blocks of repetitive material, navigational bars or other blocks of links that are greater than 7 when reading with a synthesizer or navigating using keyboard.[I#323]

  3. the content has been reviewed, taking into account the following strategies for facilitating orientation and movement, applying them as appropriate.

    1. breaking up text into logical paragraphs

    2. providing hierarchical sections and titles, particularly for longer documents

    3. revealing important non-hierarchical relationships, such as cross-references, or the correspondence between header and data cells in a table, so that they are represented unambiguously in the markup or data model

    4. dividing very large works into sections and or chapters with logical labels

    5. others?

2.5 [E4] Methods are provided to minimize error and provide graceful recovery. [was 3.5]  

Success Criteria for Checkpoint 2.5
  1. if an error is detected, feedback is provided to the user identifying the error (in an accessible form that meets core checkpoints). [I#349]

  2. where possible, the user is allowed to select from a list of options as well as to generate input text directly

  3. errors are identified specifically and suggestions for correction are provided where possible

  4. checks for misspelled words are applied and correct spellings are suggested when text entry is required.

  5. where consequences are significant and time-response is not important, one of the following is true

    1. actions are reversible where possible

    2. where not reversible, actions are checked for errors in advance

    3. where not reversible, and not checkable, a confirmation is asked before acceptance

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

Core Checkpoints for Guideline 3

3.1e [Extended Checkpoint for 3.1] Language of content can be programmatically determined.[was 1.6 partial]  

Success Criteria for Extended Checkpoint 3.1e
  1. All Core Success Criteria for this checkpoint have been met (link to 3.1 in Core)
  2. document attributes identify the natural language of the document.

Extended Checkpoints for Guideline 3

3.2 [E5] The definition of abbreviations and acronyms can be unambiguously determined. [was 4.3] 

Success Criteria for Checkpoint 3.2
  1. acronyms and abbreviations do not appear first in standard unabridged dictionaries for the language or define the first time the first time they appear or are available in a glossary on the site.[I#330]

  2. a list is provided on the page or home page of URIs to cascading dictionaries that can or should be used to define abbreviations or acronyms.[I#350]

Editorial Note:  If a standard format for doing it can be achieved, we might require that linkages to glossaries for all abbreviations and acronyms that are created by the author or site be provided.  We could also recommend that linkages to any abbreviations, acronyms, etc. used by the authors also be provided.  We could also have a weaker recommendation for acronyms and abbreviations appearing on the site that linkages to glossaries explaining all abbreviations acronyms, etc. that appear in any documents on the site be provided.   

3.3 [E6] Content is no more complex than is necessary and/or is supplemented with simpler forms of the content.   [was 4.1 and 4.2] [I#328]

Success Criteria for Checkpoint 3.3
  1. the content has been reviewed, taking into account the following strategies for evaluating the complexity of the content, applying them as appropriate.

    1. familiarity of terms and language structure

    2. reasonableness of length and complexity of sentences

    3. coherence of paragraphs (and sensibility in length)

    4. clarity of headings and linked text when read out of context

    5. accuracy and uniqueness of page titles

    6. care in the use of all-capital letters where normal sentence case might increase comprehension

    7. inclusion of non-text content to supplement text for key pages or sections of the site where they felt it was appropriate.

3.4 [E7] Layout and behavior of content is consistent or predictable, but not identical. [was 3.3 and 3.4] 

Success Criteria for Checkpoint 3.4
  1. key orientation and navigational elements (such as navigation bars) are generally found in one or two consistent locations or their locations are otherwise predictable.

  2. where inconsistent or unpredictable responses are essential to the function of the content (e.g. mystery games, adventure games, tests, etc.) the user is warned in advance of encountering them.

  3. wherever there are extreme changes in context, one of the following is true:

    1. an easy to find setting, that persists for the site visit, is provided for the user to deactivate processes or features that cause extreme changes in context or

    2. extreme changes in context are identified before they occur so the user can determine if they wish to proceed or so they can be prepared for the change

  4. user can select a different location for navigation elements in the layout of the page.[I#352]

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

Core Checkpoints for Guideline 4

4.1e [Extended Checkpoint for 4.1] Technologies are used according to specification [was 5.1]

Success Criteria for Checkpoint 4.1
  1. All Core Success Criteria for this checkpoint have been met (link to 4.1 in Core)

  2. deprecated features of markup are avoided.[I#329]

  3. Same as item #1 above, without the exception for backward compatibility.

Extended Checkpoints for Guideline 4

4.2 [E8] Technologies that are relied upon by the content are declared and widely available.[was 5.2]  

Success Criteria for Checkpoint 4.2
  1. the Web resource includes a list of the technologies (other than standard HTML) users must have in order for its content to work as intended. Users who do not have one or more of these technologies can still access and use the resource, though the experience may be degraded.[I#351]


    When determining your list of technological requirements, consider that assistive hardware and software is often slow to adapt to technological advances, and the availability of assistive technology varies across natural languages. Verify that assistive technology compatible with the technologies you choose is available in the natural language(s) of your content.

  2. a list of technologies and features, support for which is required in order for the content to be operable, has been determined and is documented in metadata and / or a policy statement associated with the content.

  3. Technologies and features on the required list are available in at least two independently-developed implementations.

Editorial Note: This checkpoint is currently in the set of extended checkpoints. The implications of this are that there is no core checkpoint that says content must transform gracefully or that it must be backwards compatible. However, if the set of core checkpoints is designed well, core conformance would result in content that transforms gracefully. This checkpoint might be too subjective or difficult to test and may be deleted.

4.3 [E9] Technologies used for presentation and user interface support accessibility or alternate versions of the content are provided that do support accessibility.[was 5.3 and 5.4]

Success Criteria for Checkpoint 4.3

Editorial Note: The WCAG WG is considering whether to delete this checkpoint because it is about the development process rather than about the characteristics of accessible content. What are the implications of deleting this checkpoint? Should there be any checkpoints related to the development process?

  1. any applications with custom user interfaces conform to at least Level A of the User Agent Accessibility Guidelines 1.0. If the application cannot be made accessible, an alternative, accessible solution is provided.

  2. the technology or combination of technologies chosen:

    1. support device independence

    2. include accessibility features

    3. have publicly documented interfaces for interoperability

    4. make use of operating system accessibility features (either directly or via the user agent) supported by assistive technologies in the natural language(s) of the content

    5. are implemented in user agents and/or proxies in the natural language(s) of the content [I#331]

  3. accessibility conventions of the markup or programming language (API's or specific markup) are used [I#331]