Web Content Accessibility Guidelines 2.0 -- Level 1 Only

W3C Working Draft 27 October 2003

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

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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 guidelines. It attempts to apply guidelines 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 prepared by the Web Content Accessibility Guidelines Working Group (WCAG WG) to show how more generalized (less HTML-specific) WCAG guielines 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


Principle 1: PERCEIVABLE. Make Content Perceivable by Any User

Guideline 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.

Level 1 Success Criteria for Guideline 1.1

  1. non-text content that can be expressed in words has a text-equivalent explicitly associated with it. [X]
    • 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. [X]

Guideline 1.2 Synchronized media equivalents are provided for time-dependent presentations.

Level 1 Success Criteria for Guideline 1.2

Editorial Note (06/10/03): There is discussion about moving some of the current success criteria from Level 1 to Level 2. 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 Level 1 guidelines of WCAG 2.0 except the Web cam at http://example.org/webcam/."

  1. an audio description is provided. [X]
  2. all significant dialogue and sounds are captioned [X]


    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. [X]
  4. if the Web content is real-time video with audio, real-time captions are provided unless the content: [X]
    • 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 guideline 1.1 (e.g., an ongoing update of weather conditions) or link to an equivalent that conforms to guideline 1.1 (e.g., a link to a weather Web site). [X]
  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. [X]

Guideline 1.3 Information, functionality, and structure are separable from presentation.

Level 1 Success Criteria for Guideline 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] [X]
  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). [Y]

Guideline 1.4 All text can be decoded into words represented in Unicode.

Level 1 Success Criteria for Guideline 1.4

Editorial Note: The CKW reorganization suggested that this guideline be combined with guideline 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. [X]

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

Guideline 2.1 All functionality is operable at a minimum through a keyboard or a keyboard interface.

Level 1 Success Criteria for Guideline 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. [X]


    refer to guideline 4.3 for information regarding user agent support.

Guideline 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.

Level 1 Success Criteria for Guideline 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: [X]
    • 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).

Guideline 2.3 User can avoid experiencing screen flicker.

Level 1 Success Criteria for Guideline 2.3

Editorial Note (06/10/03): This guideline is currently a level 1 success criterion 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 criterion will be moved to level 2."

  1. At least one of the following is true: [Y]
    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.

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

Guideline 3.1 Language of content can be programmatically determined.

Level 1 Success Criteria for Guideline 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. [X]


    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. [X]

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.

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

Guideline 4.1 Technologies are used according to specification.

Level 1 Success Criteria for Guideline 4.1

  1. for markup, except where the site has documented that a specification was violated for backward compatibility, the markup has: [X]
    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 guideline 4.3. There is an open question about whether they should be deleted since guideline 4.3 covers programmatic interfaces.

Guideline 4.2 Programmatic user interfaces are accessible or alternative, accessible versions are provided

Level 1 Success Criteria for Guideline 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. [Y]

    Editorial Note: This guideline 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. [Y]

Appendix A Glossary

Editorial Note: The WCAG WG has not tackled the definitions of the terms that we are using and acknowledges that we sometimes use terms inconsistently. We need to coordinate our terms and definitions with the WAI Glossary and are working on proposals for a variety of definitions. We have been looking at the UAAG 1.0 glossary and other glossaries within the W3C.

ability to be expressed in words

content that can be expressed accurately and unambiguously in a reasonable number of words (for example, diagrams, charts, illustrations, etc.) Content such as a musical performance or visual artwork is considered "content that can not be expressed in words," since this type of content relies heavily on the visual (or auditory) experience.[I#320]

audio description

An audio description is a verbal description 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.

audio descriptions

Audio descriptions are equivalents of visual information from actions, body language, graphics, and scene changes that are voiced (either by a human or a speech synthesizer) and synchronized with the multimedia presentation.


Captions are text equivalents of auditory information from speech, sound effects, and ambient sounds that are synchronized with the multimedia presentation.

collated script

Editorial Note: @@ that provides dialog, important sounds and important visual information in a single text document

competitive activity

A competitive activity is an activity where timing is an essential part of the design of the activity. Removal of the time element would change the performance of the participants. Versions of the activity (e.g. test) that have no time basis or time limits might be preferred and may be required for some venues but this would require a complete redesign of the activity (e.g. test) and may change the character and validation methodology and would therefore not fall under these guidelines.

complex content

Content is considered complex if the relationships between pieces of information are not easy to figure out. If the presentation of the information is intended to highlight trends or relationships between concepts, these should be explicitly stated in the summary.

Examples of complex information:

  • data tables,

  • concepts that are esoteric or difficult to understand,

  • content that involves several layers.



Editorial Note: We need to include a definition for content here.

controlled languages

Controlled languages use a restricted vocabulary taken from natural language. The purpose is to make texts easier to understand and translate. Standards generally limit words to a single meaning and prescribed part of speech. Complex syntax is avoided. Information about controlled language applications is available on the World Wide Web.


A feature is a specific component of a technology, for example an element in a markup language or a function call in an Application Programming Interface. Typically, a given feature may only be available in specific versions of the technology, and thus may need to be noted explicitly in the required list.


Functionality is the purpose or intended effect of the content. This may include presentation of information , data collection, securing a response from the user, providing user experience, linking to other content, testing, confirmation, purchasing, etc.

keyboard interface

A keyboard interface is the point where the application accepts any input that would come from the keyboard (or optional keyboard).

mechanisms that cause extreme changes in context

Mechanisms that cause extreme changes in context include:

  • opening a new browser window unexpectedly and without any nonvisual cue (back button suddenly appears nonfunctional)

  • in an auditory presentation, the speaker changes with no visual cue and no notation in captions

  • captions that do not identify a change in speaker

Common user actions include:

  • mouse movements

  • key activation

  • link selection

  • use of browser navigation buttons (e.g. back and forward)

  • opening new browser windows

Common responses to user actions include:

  • loading a new page

  • exposing/concealing content based on mouse position or keyboard focus

  • displaying the contents of a menu (auditorily or visually)

  • displaying pop-up menus or windows

  • submitting a form

It is important that responses to user actions be predictable and sensible to the end user and that interactions are consistent, both throughout the site and with commonly used interaction metaphors used throughout the Web.

media equivalents

Media equivalents present essential audio information visually (captions) and essential video information auditorily (audio descriptions).

natural languages

Natural languages are those used by humans to communicate, including spoken, written, and signed languages.

non-text content

non-text content includes but is not limited to images, text in raster images, image map regions, animations (e.g., animated GIFs), ASCII art, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video.


Scripts, applets, and programmatic objects are not covered in this definition and are addressed in guideline 4.3.


The term operable includes the concept of efficiency. That is, it implies that the device can be operated from the keyboard in a reasonably efficient fashion. Using MouseKeys or having to tab dozens of times to move through a small section of a document or page, or other unreasonably inefficient keyboard access would not qualify. If a document has a very large number of links, some mechanism other than tabbing through them one at a time needs to be provided. This might include provision of headers (for header navigation), the use of skip navigation, links, etc.[I#346]


Presentation is the rendering of the content and structure in a form that can be sensed by the user.

real-time events

Real-time events are those that are based on the occurrence of events in real-time where the events are not under the control of the author.

site navigation mechanism

A site navigation mechanism is a mechanism for easily orienting and moving about within the site. Site navigation mechanisms include but are not limited to:

  • A home page with hyperlinks on it and subsequent pages that link to the other pages at the site

  • site map(s)

  • search engine(s)

  • expanding outline(s)

  • dynamic fisheye views showing all linked pages or topics related to any page.

  • 3-D virtual representations of site content


Structure includes both hierarchical structure of the content and non-hierarchical relationships such as cross-references, or the correspondence between header and data cells in a table.The heirarchical structure of content represents changes in context. For example,

  1. A book is divided into chapters, paragraphs, lists, etc. Chapter titles help the reader anticipate the meaning of the following paragraphs. Lists clearly indicate separate, yet related ideas. All of these divisions help the reader anticipate changes in context.

  2. A bicycle is divided into wheels and a frame. Further, a wheel is divided into a tire and a rim. In an image of the bicycle, one group of circles and lines becomes "wheel" while another group becomes "frame."


A technology is a

  • markup or programming language

  • application Programming Interface (API)

  • or communication protocol

text equivalent

A text equivalent

  • serves the same function as the non-text content was intended to serve.

  • communicates the same information as the non-text content was intended to convey.

  • may contain structured content or metadata.


Text-equivalents should be easily convertible to braille or speech, displayed in a larger font or different colors, fed to language translators or abstracting software, etc.

time-dependent presentation

A time-dependent presentation is a presentation that

  • is composed of synchronized audio and visual tracks (e.g., a movie), OR

  • requires the user to respond interactively at specific times in the presentation.

unfamiliar content

Content might be unfamiliar if you are using terms specific to a particular community. For example, many of the terms used in this document are specific to the disability community.

widely available

Editorial Note: definition of "widely available" should be added here to include something which is low cost and available in many?/most? countries/languages.

Appendix E Additional Notes

Editorial Note: The following items are the additional notes from previous drafts. They are referenced from level 3 sections of some guidelines but there is not yet consensus on whether these items should be removed from the document or how they might be incorporated into other documents.

Strategies for evaluating the complexity of the content

  1. use of sentence structures that increase understanding

    • such as active voice in languages where this form helps convey information

  2. length of noun phrases

    • strings of no more than three or four nouns are easiest to understand

  3. clarity of reference with pronouns and anaphoric expressions (these refer back to something already said in the text)

    • example of potential ambiguity: "Scientists study monkeys. They eat bananas."

  4. correct use of conjunction forms and adverbs to make explicit the relationship between phrases or parts of the text

    • such as "and," "but," "furthermore," "not only"

  5. complexity of verb tenses

    • do the tenses used in a document seem overly complicated?

  6. intelligibility of verb phrases

  7. familiarity of idioms or slang

  8. logic in the order and flow of information

  9. consequences of ambiguity or abstraction

  10. improved readability of vertical lists might offer in place of long paragraphs of information

  11. use of summaries to aid understanding

  12. thoroughness in the explanation of instructions or required actions

  13. consistency in the use of names and labels

  14. clarity where the document:

    • addresses users

    • explains choices and options

    • labels options to get more information

    • instructs users how to modify selections in critical functions (such as how to delete an item from a shopping cart)

  15. application of:

    • proper markup to highlight key information

    • goal-action structure for menu prompts

    • default settings (and the ease in re-establishing them)

    • two-step "select and confirm" processes to reduce accidental selections for critical functions

    • calculation assistance to reduce the need to calculate

  16. testing with potential users for ease of accessibility

  17. use of a controlled language

  18. providing support for conversion into symbolic languages

  19. adding non-text content to the site for key pages or sections specifically to make the site more understandable by users who cannot understand the text only version of the site.

Common ideas for making content consistent and predictable

  1. place navigation bars in a consistent location whenever possible

  2. similar layout for user interface components should be used for sections or whole site

  3. similar user interface components should be labeled with similar terminology

  4. use headers consistently

  5. use templates for consistent presentation of sections or whole site

  6. pages with similar function should have similar appearance and layout

  7. controls that look or sound the same should be designed to act the same

  8. conventions likely to be familiar to the user should be followed

  9. unusual user interface features or behaviors that are likely to confuse the first-time user should be described to the user before they are encountered

  10. allow the user to select different page layout templates for presentation of pages. (e.g. 3 column, linear, adding extra orientation or navigation elements, etc.) [I#353]