Copyright 2001 W3C (MIT, INRIA, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply.
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.
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" 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.
Please send comments on this document to w3c-wai-gl@w3.org. The archives for this list are publicly available.
This document outlines design principles for creating accessible Web sites. When these principles are ignored, individuals with disabilities may not be able to access the content at all, or they may be able to do so only with great difficulty. When these principles are employed, they also make Web content accessible to a variety of Web-enabled devices, such as phones, handheld devices, kiosks, network appliances, etc. By making content accessible to a variety of devices, that content will also be accessible to people in a variety of situations.
The design principles in this document represent broad concepts that apply to all Web-based content. They are not specific to HTML, XML, or any other technology. This approach was taken so that the design principles could be applied to a variety of situations and technologies, including those that do not yet exist.
In order to facilitate understanding of the guidelines and to help people focus in on just the parts they need, the guidelines are presented as a set of interrelated documents. There are basically 3 layers to the guidelines information.
The top layer is titled "Web Content Accessibility Guidelines 2.0". It is the document you are currently reading. This document provides:
In addition to the general guidelines, there are a series of Technology Specific Guidelines documents. These documents provide information on what is required when using different technologies in order to meet the WCAG 2.0 access guidelines. These documents are also normative.
Reviewer's Note: are we doing this level now?
In separate Techniques Documents are code examples, screen shots, and other information specific to a technology. These documents are non-normative and do not contain requirements. Rather they contain different strategies for meeting the requirements as well as the current preferred approaches where they exist. Examples include:
(These will become active links as the corresponding working drafts are published)
These guidelines have been written to meet the needs of many different audiences from policy makers, to managers, to those who create Web content, to those who code the pages. Every attempt has been made to make the document as readable and usable as possible while still retaining the accuracy and clarity needed in at technical guideline. For first time users, the work of the Education and Outreach Working Group of the Web Accessibility Initiative is highly recommended.
The guidelines cover a wide range of issues and recommendations for making web content more accessible. They include recommendations to make pages accessible and usable by people with a full range of disabilities. In general, the guidelines do not include standard usability recommendations except where they have specific ramifications for accessibility beyond standard usability impacts.
This WCAG 2.0 Working Draft does not assign priorities to checkpoints, as did WCAG 1.0. Instead, each of the checkpoints has levels of implementation listed for it. There are 3 levels labeled "Minimum", "Level 2", and "Level 3". The Main WCAG 2.0 Draft document does not include technology specific implementation requirements or techniques, but it does include links to technology specific requirements as well as technology specific examples and techniques.
Version 2.0 of the WCAG is a follow-on and evolution of WCAG 1.0 and reflects feedback received since the publication of WCAG 1.0 in May 1999. Although the same approaches to accessibility are followed in 1.0 and 2.0, the organization and structure have been improved significantly.
The Web Content Accessibility Guidelines Working Group is working carefully to enable organizations and individuals that have adopted WCAG 1.0 in the past to make a smooth transition to WCAG 2.0. To facilitate this transition, please refer to the Checkpoint Mapping Between WCAG 1.0 and the WCAG 2.0 Working Draft for more detail on current correspondences.
In order to claim any conformance to the guidelines it is necessary to satisfy the "MINIMUM" success criteria of every checkpoint. The minimum criteria represent those aspects of the checkpoint requirements which, in the absence of a full implementation, will nonetheless offer substantial benefit to people with disabilities by removing barriers that would otherwise make it difficult or impossible to access the content. The Level 2 and Level 3 criteria build upon this functionality, making the content accessible to people who would not be able to access it, or could do so only with substantial difficulty, if only the minimum criteria had been met.
Sites which go beyond the Minimum level of conformance can claim conformance at higher levels in several ways.
The overall goal is to create Web content that is perceivable, operable, navigable, and understandable by the broadest possible range of users and compatible with their wide range of assistive technologies, now and in the future.
Accessible Web content benefits a variety of people, not just people with disabilities. In the physical world, ramps are used by bicycles, people pushing strollers, and people in wheelchairs. Similarly, accessible Web content is usable by a variety of people with and without disabilities. For example, people who are temporarily operating under constrained conditions like operating in a noisy environment or driving their car where their eyes are busy. Likewise, a search engine can find a famous quote in a movie if the movie is captioned.
Note:These principles apply only to Web content presented to a human reader. A structured database or metadata collection where the data is intended for use by another machine and thus requires no interface lies outside the scope of these guidelines.
Here are a few scenarios, by no means an exhaustive list of the variations and types of disabilities and needs:
If Web content employs the design principles described in this document, then users should be able to access the content using adaptive strategies and assistive technologies. A screen reader is an example of an assistive technology that reads the page aloud. There are many other tools people with disabilities employ to make use of Web content. For more in-depth scenarios of people with disabilities using accessible and inaccessible Web content, please read "How People with Disabilities Use the Web".
These guidelines provide the basic requirements for designing accessible Web content. This document is not designed to provide the background needed to learn about accessible Web design in a thorough or effective manner for those interested in learning. Readers are therefore referred to the Education and Outreach Working Group of the Web Accessibility Initiative.
Essential to any access to Web content is the ability of the user to have the information presented in a form which they can perceive.
The checkpoints under this guideline impact individuals with sensory disabilities by allowing the information to be transformed and presented in a form which they can perceive. They also impact individuals with cognitive and language disabilities by ensuring that the information is in a format that can be perceived by mainstream and assistive technologies which can read the content to them as well as (increasingly over time) transform and present it in a form which is easier for them to understand.
A text equivalent
Note: 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.
Non-text content includes but is not limited to images, text in raster images, image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, scripts that present content, 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.
Individuals who are blind, have low vision, have cognitive disabilities or have trouble reading text for any reason can have the text read aloud to them. Individuals who are deaf, are hard of hearing or who are having trouble understanding the audio information for any reason can read the text presentation or have it translated and presented as sign language. Individuals who are blind or deaf-blind can have the information presented in braille.
exception: if content is rebroadcast from another medium or resource that complies to broadcast requirements for accessibility (independent of these guidelines), the rebroadcast satisfies the checkpoint if it complies with the other guidelines.
A time-dependent presentation is a presentation which
Media equivalents present essential audio information visually (captions) and essential video information auditorily (audio descriptions).
People who are deaf or have a hearing loss can access the auditory information through the captions. People who are blind or have low vision as well as those with cognitive disabilities who have difficulty interpreting visually what is happening benefit from the audio descriptions of the visual information.
People without disabilities also benefit from the media equivalents. People in noisy environments or with muted sound often use captions. Captions are used by many to develop language and reading skills. Audio descriptions also provide visual information for people who are temporarily looking away from the video presentation such as when following an instructional video and looking at their hands. Captions and text descriptions can also be used to index and search media files.
Note:Time-dependent presentations that require dual, simultaneous attention with a single sense can present significant barriers to some users. Depending on the nature of the of presentation, it may be possible to avoid scenarios where, for example, a deaf user would be required to watch an action on the screen and read the captions at the same time. However, this would not be achievable for live broadcasts (ex. a football game). Where possible, provide content so that it does not require dual, simultaneous attention or so that it gives the user the ability to effectively control/pause different media signals.
Content is the information or meaning and function.
Presentation is the rendering of the content and structure in a form that can be sensed by the user.
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.
Separating content and structure from presentation allows Web pages to be presented differently to meet the needs and constraints of different users without losing any of the information or structure. For example, information can be presented via speech or braille (text) that was originally intended to be presented visually.
The following are additional ideas for enhancing a site along this particular dimension:
Note: This checkpoint addresses the need for authors to provide sufficient information so that text can be identified correctly by technologies used to render the text (e.g. voice synthesizers) so that the words can be accurately produced and perceived. This checkpoint does not deal with providing definitions or expanded text for words, abbreviations, foreign phrases etc. These are covered under checkpoint 4.3 since they deal with understanding of the content.
Natural languages are those used by humans to communicate, including spoken, written, and signed languages.
Phrases from various languages, acronyms and abbreviations are often interspersed in writing. When these phrases are identified, a speech synthesizer can voice text with the appropriate accent and pronunciation. When they are not identified, the speech synthesizer will use the default accent and pronunciation of the language on the rest of the page, which can make the phrase unintelligible. Identifying changes in language and marking abbreviations and acronyms as such will also allow a tool to ask for automatic translations of that content. When editing content, authoring tools can switch between appropriate spelling dictionaries.
Facilitating unambiguous decoding of characters and words in content is also helpful for individuals who are learning to read or learning a second language.
Also essential to accessibility is the ability to be able to operate all of the interface elements on the page without requiring the use of specific input devices.
This guideline impacts individuals who are blind, individuals who have low vision and have trouble with eye-hand coordination input devices, individuals with physical disabilities who cannot handle direct pointing devices accurately, and individuals with language and learning disabilities who would like to use speech input now or in the future.
Character input is defined as those characters that can be mapped to the character set of the W3C Character Model (which is based on Unicode).
Individuals who are blind (and cannot use pointing devices) can have access to the functionality of the Web content or site.
Individuals with severe physical disabilities can use speech input (which simulates keystrokes) to both enter data and operate the interface elements on the page.
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.
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.
People with reading disabilities, cognitive disabilities, and learning disabilities often need longer than most people to read and comprehend written text. People with physical disabilities might not be able to move quickly or accurately enough to interact with moving objects.
Content that is updated often might not be processed and read in time or in the proper order by an assistive technology or voice browser.
Examples of content that requires a response within a timed interval:
Reviewer's Note: Trace is currently in the process of exploring an automated flicker testing tool.
People with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 3 to 49 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second.
People with distractibility problems may not be able to focus on page content with flicker occurring in the same visual field.
Key to effective use of Web content is the ability to obtain and keep one's orientation within a document and/or Web site, and the ability to efficiently move about in the site or document.
Note:Because the form and origin of content (including letters, poetry, historical documents, etc.) varies so greatly, specific criteria for the type and amount of structure to be put into content can not be standardized. Objective success criteria cannot therefore be formulated that would apply across media and documents. Advisory recommendations are, however, listed below to provide guidance in adding key structural elements into the content. See also the techniques documents for the different technologies.
The structure of content represents changes in context. For example,
When the logical structure is provided in markup or a data model,
Note:Because the form and origin (including letters, art, historical documents, etc) of content varies so greatly, specific criteria for the type and amount of emphasis to be provided can not be standardized. Objective success criteria cannot therefore be formulated that would apply across media and documents. Advisory recommendations are however listed below to provide guidance in emphasizing the structure of content. See also the techniques documents for the different technologies.
Note: Ensure that the structural and semantic distinctions are provided in the markup or data model. Refer to checkpoint 2.2.
Presentation that emphasizes structure:
A site navigation mechanismis a mechanism for easily orienting and moving about within the site. Site navigation mechanisms include but are not limited to:
Providing different navigation mechanisms can provide a better match between different people's skills, background knowledge, visual vs. text orientation, and the type of information they are seeking at the moment.
People with cognitive disabilities may find it easier to ask for what they want than to deduce its location from categorical choices.
People with low vision or blindness may find search techniques that fetch everything that relates to a topic of interest to be easier than techniques that require them to scan lists or pages for the items.
Presentation includes, but is not limited to:
Consistency helps users predict where to find information on each page of your site. It also helps users determine the relationships between items in the content. This understanding of the structure helps users navigate and orient themselves.
However, differences in presentation help users determine that they have succeeded in loading a new page. Pages that are clearly different also makes it easier for users to tell where they are and to remember where information is located.
Mechanisms that cause extreme changes in context include:
If the user is unable to detect extreme changes because the cues are not obvious, then they may not realize the context has changed. People who are blind will not see obvious visual cues such as a new window popping up and may not know why the back button no longer works. Some people with low vision, some people with dyslexia and other people who have difficulty interpreting visual cues may need additional cues to detect extreme changes in context.
Providing responses to user actions is important feedback for the user. This lets them know that your site is working properly and encourages them to keep interacting. When the user receives an unexpected response, they might think something is wrong or broken. Some people might get so confused they will not be able to use your site. Common responses to user actions:
These actions should be predictable and sensible to the end user. Make interactions consistent, both throughout the site and with commonly used interaction metaphors used throughout the Web.
Reviewer's Note: some of these examples are very brief. Should they be expanded and clarified with further details?
People with writing disabilities and people with dyslexia often have difficulty writing text in forms or other places that need text input. People with speech disabilities might not be recognized properly in voice input applications.
To help people understand the information you are presenting, consider the various ways that people learn. Keep in mind the variety of backgrounds and experiences people will bring to your site. Using language, illustrations, and concepts that they are likely to know, highlighting the differences and similarities between concepts, and providing explanations for unusual terms can all facilitate understanding.
Note: It is very difficult to determine what makes writing clear and simple for all topics. Some content is derived from other sources and is copyrighted so it cannot be altered. Some materials or topics cannot be communicated accurately in simple language. Also, since some people cannot understand the content no matter how simply it is written, it is not possible to make any content accessible to everyone. Specific objective criteria that could be applied across all types of content are therefore not possible. Advisory recommendations are however listed below to provide guidance in this area. See also the techniques documents for the different technologies.
Reviewer's Note: The list above is a partial list of ideas. We're still working on a longer list of ideas to be used in furthering the development of this checkpoint..
Authors should strive for clear and simple writing to aid all users, especially those with cognitive, learning, and/or reading disabilities. This should not discourage you from expressing complex or technical ideas. Using clear and simple language also benefits people whose first language differs from your own, including those people who communicate primarily in sign language.
Note: Supplementing text with non-text (e.g. graphics, sound, smell, etc) is useful for all users. However there are no clear guidelines as it relates to disability. Specific objective criteria that could be applied across all types of content are therefore not possible. Advisory recommendations are, however, listed below to provide guidance in this area. See also the techniques documents for the different technologies.
Reviewer's Note: Do we have any items to add here or do we just include examples below?
Non-text content - includes images, text in raster images, image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, scripts, 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.
Reviewer's Note: Is this definition adequate?
Sounds, graphics, videos and animations can help make concepts presented in a Web site easier to understand, especially for people with cognitive, reading, or learning disabilities or those who are unfamiliar with the language of the text of the site.
Note:Designers need to be cautious in deciding when to use illustrations. Reading a picture is probably a learned activity that is easier for some than others. Some users skip the pictures; others read only the pictures. Designers must also recognize that visual conventions are not universal and that individuals develop their own mental schema and expectations in interpreting visual information.
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:
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.
Summarizing information that is difficult to understand helps people who do not read well. Providing a summary of the visual cues that show relationships between complex information helps people who do not use visual cues or who have difficulty using visual cues. For example, people who are blind do not use any visual cues, while people with dyslexia or with low vision might have difficulty interpreting visual cues.
Defining key terms and specialized language will help people who are not familiar with the topic. Providing the expansion of abbreviations and acronyms not only helps people who are not familiar with the abbreviation or acronym but can clarify which meaning of an abbreviation or acronym is appropriate to use. For example, the acronym "ADA" stands for both the American with Disabilities Act as well as the American Dental Association.
Reviewer's Note: Are protocols relevant to this checkpoint? If so, why, and should we require that they be used according to specification? Obviously there are interoperability advantages in doing so, but is this pertinent to accessibility?
When languages, API's, and protocols are used according to specification, tools that use the results will be able to do so as intended and expected.
Benefits of determining and documenting baseline user agent requirements:
Benefits of designing for backward compatibility:
Markup languages, multimedia formats, software interface standards, etc., vary in their support of accessibility. When choosing which technologies to use, consider how easy it is to apply these guidelines.
Asking someone to access your Web site without their assistive technology is like asking someone to access a building without their wheelchair. Assistive technologies are an essential part of the lives of many people with disabilities.
Reviewer's Note: Should we include only the definitions of terms appearing in the guidelines or is there some subset of key terms from the glossary that should also be included? We also need to make sure that the glossary definitions are the same as the definitions which appear in the guidelines themselves. For now, a simple list of the terms that are defined in this document are included below. Definitions for each term will be included at a later date.
Participants in the WCAG Working Group
Since the release of WCAG 1.0 in May 1999, the WCAG Working Group has received feedback on priorities of checkpoints, the usability of the set of documents, and requests for clarifications on the meaning of specific checkpoints and what is needed to satisfy them. Thus, it is intended that WCAG 2.0:
For a checkpoint by checkpoint comparison, refer to the Checkpoint Mapping Between WCAG 1.0 and WCAG 2.0 Working Draft.
We hope that WCAG 2.0 will have several improvements over WCAG 1.0. While the primary goal of WCAG 2.0 is the same as WCAG 1.0 (to promote accessibility of Web content) additional goals for WCAG 2.0 include improvements that will:
For more information about the improvements in WCAG 2.0, please refer to Requirements for WCAG 2.0.
Reviewer's Note: Links within the document will be turned into references and the links to those documents will be listed here as references. They are inline for the time being.