Web Content Accessibility Guidelines 2.0 -- View 1 - Required Only

W3C Working Draft 23 Sept. 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 is the fourth in a series of reorganization proposals.


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

1.1 [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.

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).

  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.

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.

  2. all significant dialogue and sounds are captioned


    If the Web content is real-time and audio-only and not time-sensitive and not interactive a transcript or other non-audio equivalent is sufficient.

    Editorial Note: This exception also applies to item 3.

  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.

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.

    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 through color is also available without color (e.g. through context or markup or non-color dependent coding). [I#317]

  3. 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).

1.4 [CORE] All text can be decoded into words represented in Unicode.

Required Success Criteria for Checkpoint 1.4

Editorial Note: The CKW reorganization suggested that this checkpoint be combined with checkpoint 3.2. [I#442]

  1. text in the content is provided in Unicode or sufficient information is provided so that it can be automatically mapped back to Unicode.

Extended Checkpoints for Guideline 1

1.5 [E1] Structure has been made perceivable through presentation. [I#439]

Required 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.

1.6 [E2] Foreground content is easily differentiable from background for visual default presentations.

Required Success Criteria for Checkpoint 1.6
  1. 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]

1.7 [E3] Foreground content is easily differentiable from background for auditory default presentations.

Required Success Criteria for Checkpoint 1.7
  1. 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).

1.8 [E4] [color vision is not required to perceive content (or something like this to allow color-coding issues to exist at extended checkpoint level)]

Required Success Criteria for Checkpoint 1.8
  1. (something to achieve an effect where information can be perceived with common color deficiencies)

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

Core Checkpoints for Guideline 2

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

Required Success Criteria for Checkpoint 2.1
  1. all of the functionality of the content, where the functionality or its outcome can be expressed 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.

Required Success Criteria for Checkpoint 2.2
  1. content is designed so that time limits are not an essential part of interaction or 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,

    • 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.

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. 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.

Extended Checkpoints for Guideline 2

2.4 [E5] Mechanisms have been added to facilitate orientation and movement in content.

Required Success Criteria for Checkpoint 2.4

Editorial Note: The CKW reorganization proposed that all of the items in required be removed and proposed a rewording of the item in best practice that addressed logical, linear reading order. [I#441]

  1. In documents greater than 50,000 words or sites larger than 50 perceived pages, at least one of the following is 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]

2.5 [E6] Methods are provided to minimize error and provide graceful recovery.

Required Success Criteria for Checkpoint 2.5

Editorial Note: The CKW proposal suggested that this required success criterion be combined with one of the best practice items and that another best practice item be moved up. [I#440]

  1. if an error is detected, feedback is provided to the user identifying the error (in an accessible form that meets core checkpoints).

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

Core Checkpoints for Guideline 3

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

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.


    1. Foreign words or phrases that are found in standard unabridged dictionaries for the natural language of the content do not need to be marked.

    2. This success criterion applies only to foreign words, not to imaginary words, dialect abbreviations and other words that may not be found in an unabridged dictionary of the primary language but that are not foreign words.

  2. [???] document attributes identify the natural language of the document.

Editorial Note: In techniques discussion, it has been argued that language attributes for documents are as important as identifying changes in language within documents. Moving it up here for future discussion.

Extended Checkpoints for Guideline 3

3.2 [E7] The definition of abbreviations and acronyms can be unambiguously determined.

Editorial Note: The CKW reorganization suggested that this checkpoint be combined with checkpoint 1.4. [I#442]

Required 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]

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 [E8] Content is no more complex than is necessary and/or is supplemented with simpler forms of the content.  

Required 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 [E9] Layout and behavior of content is consistent or predictable, but not identical.  

Required 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

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

4.1 [CORE] Technologies are used according to specification.

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

    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.

4.2 [CORE] Programmatic user interfaces are accessible or alternative, accessible versions are provided

Required Success Criteria for Checkpoint 4.2
  1. any custom user interface elements of the content conform to at least Level A of the User Agent Accessibility Guidelines 1.0. If the custom user interfaces cannot be made accessible, an alternative solution is provided that meets WCAG 2.0 (including this provision) to the level claimed.

    Editorial Note: This checkpoint includes a slightly reworded version of the suggestions from CKW reorganization. However, the following elements appeared to be redundant with the first sentence. Can they be removed?

    1. If the application renders visual text, it should conform to the VisualText checkpoints.

    2. If the application renders images, it should conform to the Image checkpoints.

    3. If the application renders animations, it should conform to the Animation checkpoints.

    4. If the application renders video, it should conform to the Video checkpoints.

    5. If the application renders audio, it should conform to the Audio checkpoints.

    6. If the application performs its own event handling, it should conform to the Events checkpoints.

    7. If the application implements a selection mechanism, it should conform to the Selection checkpoints.

    8. The application should support keyboard access per UAAG 1.0 checkpoints 1.1 and 6.7.

    9. If the application implements voice or pointer input, it should conform to the Input Modality checkpoints.

    10. accessibility conventions of the markup or programming language (API's or specific markup) are used (@@in UAAG somewhere?)

  2. plug-ins required to access the content conform to at least Level A of UAAG 1.0. If required plug-ins are not accessible, an alternative solution is provided that conforms to WCAG 2.0.

Extended Checkpoints for Guideline 4

4.3 [E10] Technologies that are relied upon by the content are declared and widely available.

Required Success Criteria for Checkpoint 4.3
  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.


    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.

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.