Abstract
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 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 w3c-wai-gl@w3.org. The archives for this
list are 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.
Introduction
Purpose
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.
How to read this document
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.
1 - Top layer - Overview of Design Principles, Guidelines,
Checkpoints
The top layer is titled "Web Content Accessibility Guidelines
2.0". It is the document you are currently reading. This document
provides:
- An introduction
- The 5 major Guidelines for accessibility (Perceivable, Operable,
Navigable, Understandable and Robust).
- The (non-technology-specific) checkpoints for each guideline (21 in
total).
- Success criteria (normative), and definitions, benefits and examples
(all non-normative) for each checkpoint
- An appendix containing definitions, references and other support
information.
2 - Technology-specific Checklists
In addition to the general guidelines, there will be a series of
technology-specific checklist documents. These documents will provide
information on what is required when using different technologies in order to
meet the WCAG 2.0 Working Draft access guidelines.
Reviewer's Note: These checklists do not
yet exist. At the present time the checklists are expected to be
non-normative, though no formal decision has been made.
3 - Bottom layer - Technology-specific application information
The Techniques Documents will include code examples, screen shots, and
other information specific to a technology. These documents will be
non-normative. They will contain different strategies for meeting the
requirements as well as the current preferred approaches where they exist.
Examples include:
- Hypertext Markup Language (HTML) and Extensible Hypertext Markup
Language (XHTML™) Techniques
- Cascading Style Sheets (CSS) Techniques
- Server-side scripting Techniques
- Client-side scripting Techniques
- Scalable Vector Graphics (SVG) Techniques
- Synchronized Multimedia Integration Language (SMIL) Techniques
- Extensible Markup Language (XML) Techniques
(These will become active links as the corresponding working drafts
are published)
Audience
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 a technical specification. For first time users, the work
of the Education and Outreach Working
Group of the Web Accessibility Initiative is highly recommended.
Scope
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.
Priorities and Techniques
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 Working 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.
This Working Draft of WCAG 2.0 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 are currently using
WCAG 1.0 (which remains stable and referenceable at this time) to ensure that
they will eventually be able to make a smooth transition to WCAG 2.0. To
understand how this eventual transition would be facilitated, please refer to
the (draft) 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.A
full discussion of the underlying rationale of the conformance scheme,
including the three levels of conformance, is presented in Appendix B.
Sites which go beyond the Minimum level of conformance can claim
conformance at higher levels in several ways.
- If they meet all of the criteria for Level 2 or Level 3 they can claim
conformance at those levels.
- If they meet some but not all of the criteria for Level 2 then can
claim conformance at Level 1+.
- If they meet all of the criteria for level 2 and some but not all of
the criteria for Level 3 then can claim conformance at Level 2+.
- It is possible and recommended that sites report specifically which
criteria they have met within each of the guidelines and checkpoints.
This can be done using [Reviewer's
Note: method not yet defined].
Overview of Design Principles
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.
- Perceivable. Ensure that all content can be presented
in form(s) that can be perceived by any user - except those aspects of
the content that cannot be expressed in words.
- Operable. Ensure that the interface elements in the
content are operable by any user.
- Navigable. Facilitate content orientation and
navigation
- Understandable. Make it as easy as possible to
understand the content and controls.
- Robust. Use Web technologies that maximize the ability
of the content to work with current and future accessibility technologies
and user agents.
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.
User needs
Here are a few scenarios, by no means an exhaustive list of the variations
and types of disabilities and needs:
- Someone who cannot hear will want to see the information normally
presented via sound.
- Someone who cannot see will want to hear or read through braille
information that is usually presented visually.
- Someone who does not have the strength to move quickly or easily will
want to use as little movement as possible and have as much time as they
need when operating Web interfaces.
- Someone who does not read well may want to hear the information read
aloud.
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".
Designing Accessible Web Content
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.
Guideline 1 - Perceivable.
Ensure that all intended function and information can be presented in form(s)
that can be perceived by any user - except those aspects that cannot be
expressed in words.
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.
Checkpoint 1.1 For all non-text content that
can be expressed in words, provide a text equivalent of the function or
information the non-text content was intended to convey.
Success Criteria
You will have successfully met Checkpoint 1.1 at the Minimum Level
if:
- non-text content that can be expressed in words has a text-equivalent
explicitly associated with it.
- non-text content that can not be expressed in words has a descriptive
label provided as its text-equivalent.
- The text equivalent should fulfill 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).
You will have successfully met Checkpoint 1.1 at Level 2 if:
- the text-equivalent has been
reviewed and is believed to fulfill 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)
- a conformance claim associated with the content asserts
conformance to this checkpoint at level 2.
You will have successfully met Checkpoint 1.1 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Checkpoint 1.2 Provide synchronized media
equivalents for time-dependent presentations.
Success criteria
You will have successfully met Checkpoint 1.2 at the Minimum Level
if:
- an audio description is provided of all visual
information in scenes, actions and events (that can't be perceived from
the sound track).
- The audio description should include all significant visual
information in scenes, actions and events (that can't be perceived
from the sound track) to the extent possible given the constraints
posed by the existing audio track (and constraints on freezing the
audio/visual program to insert additional auditory description).
- all significant dialogue and sounds are captioned
exception: if the Web content is real-time
audio-only, if not time-sensitive (news, emergency, etc.), and not
interactive, a transcript or other non-audio equivalent is
sufficient.
- descriptions and captions are synchronized with
the events they represent.
- 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
- if the Web content is
real-time non-interactive video (e.g. a Webcam of ambient conditions), an
accessible alternative is provided that achieves the purpose of the
video. If the author's purpose is to provide real-time information, a
media equivalent is provided that conforms to checkpoint 1.1, or a link
is provided to content elsewhere which conforms to checkpoint 1.1 (e.g. a
link to a weather Web site).
- 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.
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.
You will have successfully met Checkpoint 1.2 at Level 2 if:
- the audio description has been
reviewed and is believed to include all significant visual information
in scenes, actions and events (that can't be perceived from the sound
track) to the extent possible given the constraints posed by
the existing audio track (and constraints on freezing the audio/visual
program to insert additional auditory description).
- A conformance claim associated with the content asserts
conformance to this checkpoint at level 2 or level 3.
- captions and Audio descriptions are provided for all live broadcasts
that are professionally produced.
- if Web content is an interactive audio-only presentation, the
user is provided with the ability to view only the captions, the captions
with the audio, or both together.
You will have successfully met Checkpoint 1.2 at Level 3 if:
- a text document (a "script") that includes all audio and visual
information is provided.
- captions and Audio descriptions are provided for all live broadcasts
which provide the same information.
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Checkpoint 1.3 Make all content and structure available
independently of presentation.
Success criteria
You will have successfully met Checkpoint 1.3 at the Minimum Level
if:
- any information that is conveyed through presentation formatting is
also provided in either text or structure.
- the following can be derived programmatically (i.e. through assistive
technology compatible markup or data model) from the content without
interpreting presentation.
- any hierarchical elements and relationships, such as headings,
paragraphs and lists
- any non-hierarchical relationships between elements such as
cross-references and linkages, associations between labels and
controls, associations between cells and their headers, etc.
- any emphasis
You will have successfully met Checkpoint 1.3 at Level 2 if:
- (presently no additional criteria for this level.)
You will have successfully met Checkpoint 1.3 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Checkpoint 1.4 Emphasize
structure through presentation(s), positioning, and labels.
Success criteria
You will have successfully met Checkpoint 1.4 at the Minimum Level
if:
- the structural elements present have a different visual appearance or
auditory characteristic than the other structural elements.
You will have successfully met Checkpoint 1.4 at Level 2 if:
- the structural emphases are chosen to be distinct for different major
display types (e.g. black and white, small display, mono audio
playback).
You will have successfully met Checkpoint 1.4 at Level 3 if:
- content is constructed such that users can control the presentation of
the structural elements.
- alternate presentation formats are available to vary the emphasis of
the structure.
The following are additional ideas for enhancing a site along this
particular dimension:
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.
- for visual presentations, use font variations, styles, size and white
space to emphasize structure.
- use color and graphics to emphasize structure.
- for auditory presentations, use different voice characteristics
and/sounds for major headings, sections and other structural
elements.
- if content is targeted for a specific user group and the presentation
of the structured content is not salient enough to meet the needs of your
audience, use additional graphics, colors, sounds, and other aspects of
presentation to emphasize the structure.
- provide a table of contents or navigation map of the document.
Note: Ensure that the structural and semantic
distinctions are provided in the markup or data model. Refer to checkpoint
1.3.
Checkpoint 1.5 Ensure that foreground
content is easily differentiable from background for both auditory and visual
presentations.
Success criteria
You will have successfully met Checkpoint 1.5 at the Minimum Level
if:
- no text content is presented over a background picture, color or
pattern that seriously interferes with readability unless the background
picture or pattern can be easily removed.
- prepared audio presentations do not have background sounds that
seriously interfere with foreground auditory content.
You will have successfully met Checkpoint 1.5 at Level 2 if:
- content that might create a
problem has been run through a simulator for major types of color
blindness and has been found to remain easily readable
- a conformance claim associated with the content asserts
conformance to this checkpoint at level 2.
You will have successfully met Checkpoint 1.5 at Level 3 if:
- there are no background pictures or patterns behind foreground
content
- background sounds are at least 20 db lower than foreground content.
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Checkpoint 1.6 Provide information needed
for unambiguous decoding of the characters and words in the content.
Success criteria
You will have successfully met Checkpoint 1.6 at the Minimum Level
if:
- text in the content is provided in Unicode or sufficient information is
provided so that it will be automatically mapped back to Unicode.
You will have successfully met Checkpoint 1.6 at Level 2 if:
- 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.
- abbreviations and acronyms are clearly identified where they occur.
(See also checkpoint 4.3.)
- symbols such as diacritic marks that are found in standard usage of the
natural language of the content, and necessary for unambiguous
interpretation of words, are present or another standard mechanism for
disambiguation is provided.
You will have successfully met Checkpoint 1.6 at Level 3 if:
- the primary natural language of the content is identified at the page
level.
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
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.
Guideline 2 - Operable.
Ensure that the interface elements in the content are operable by any
user.
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.
Checkpoint 2.1 Ensure that all of
the functionality of the content is operable through character input to the
content or user agent.
Success criteria
You will have successfully met Checkpoint 2.1 at the Minimum Level
if:
- content uses only event handlers that are designed to be operable
through character input.
- Note: refer to checkpoint 5.3 for information
regarding user agent support.
You will have successfully met Checkpoint 2.1 at Level 2 if:
- wherever a choice between event handlers is available and supported,
the more abstract event is used.
You will have successfully met Checkpoint 2.1 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Checkpoint 2.2 Allow users to control
any time limits on their reading, interaction or responses unless control is
not possible due to the nature of real-time events or competition.
Success criteria
You will have successfully met Checkpoint 2.2 at the Minimum Level
if:
- 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 10 times the 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).
You will have successfully met Checkpoint 2.2 at Level 2 if:
- (presently no additional criteria for this level.)
You will have successfully met Checkpoint 2.2 at Level 3 if:
- activities are designed so that time limits are not an essential part
of the activity (e.g. competition, testing, etc. are not time based).
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Checkpoint 2.3 Avoid causing the screen to
flicker.
Success criteria
You will have successfully met Checkpoint 2.3 at the Minimum Level
if:
- At least one of the following is true:
- content was not designed to flicker (or flash) in the range of 3 to
49 Hz.
- Reviewer's Note: We would
like to include a criteria here which 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.
- 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.
You will have successfully met Checkpoint 2.3 at Level 2 if:
- animation or other content does
not visibly or purposely flicker between 3 and 49 Hz.
- 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.
- a conformance claim associated with the content asserts
conformance to this checkpoint at level 2
- (tougher test - that would make pages pass with even slower equip.
Equip might be old or just slow for other reasons)
You will have successfully met Checkpoint 2.3 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Reviewer's Note: Trace is currently in
the process of exploring an automated flicker testing tool.
Guideline 3 - Navigable.
Facilitate content orientation and navigation
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.
Checkpoint 3.1 Provide structure
within content.
Success criteria
You will have successfully met Checkpoint 3.1at the Minimum Level if:
- the following minimum structure elements are present.
- titles on major sections of long documents
- paragraphs
You will have successfully met Checkpoint 3.1 at Level 2 if:
- the content has been reviewed, taking into account the
additional ideas listed below, and is believed to contain
as much
structure as is possible and appropriate
- a conformance statement associated with the content asserts
conformance to this checkpoint at level 2 or level 3.
You will have successfully met Checkpoint 3.1 at Level 3 if:
- information is provided that would allow an assistive technology to
determine at least one logical, linear reading order
- diagrams are constructed in a fashion so that they have structure that
can be accessed by the user.
The following are additional ideas for enhancing a site along this
particular dimension
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.
- break up text into logical paragraphs.
- provide hierarchical sections and titles, particularly for longer
documents
- reveal 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.
- divide very large works into sections and or chapters with logical
labels.
- others?
Checkpoint 3.2 Provide multiple methods to
explore sites that are more than two layers deep.
Success criteria
You will have successfully met Checkpoint 3.2 at the Minimum Level
if:
- sites that have more than two layers have at least one other method for
exploration besides using the links on the home page. (A home page and
one layer of pages linked off of it would be two layers)
- a link to the alternate exploration method(s) is provided on the home
page.
You will have successfully met Checkpoint 3.2 at Level 2 if:
- sites that have documents that span multiple files either provide the
documents as a single file or provide a search function which would allow
the user to search for a word across only the files that make up that
document.
You will have successfully met Checkpoint 3.2 at Level 3 if:
- large documents (greater than 50,000 words) include multiple mechanisms
for navigation such as a hyperlinked table of contents, internal
hyperlinks, an ability to collapse by headers, etc.
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Checkpoint 3.3 Use consistent but not
necessarily identical presentation.
Success criteria
You will have successfully met Checkpoint 3.3 at the Minimum Level
if:
- key orientation and navigational elements are generally found in one or
two locations or their locations are otherwise predictable.
You will have successfully met Checkpoint 3.3 at Level 2 if:
- the content has been reviewed, taking into account the
additional ideas listed below, and it has been concluded
that key
orientation and navigational
elements are generally found in one or two locations, or their locations
are otherwise predictable
- a conformance claim associated with the content asserts
conformance to this checkpoint at level 2.
You will have successfully met Checkpoint 3.3 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- place navigation bars in a consistent location whenever possible
- similar layout for user interface components should be used for
sections or whole site,
- similar user interface components should be labeled with similar
terminology
- use headers consistently
- use templates for consistent presentation of sections or whole site
- pages with similar function should have similar appearance and
layout
Checkpoint 3.4 Provide consistent
and predictable responses to user actions.
Success criteria
You will have successfully met Checkpoint 3.4 at the Minimum Level
if:
- 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.
- wherever there are extreme changes in context, one of the following is
true:
- 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
- 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
You will have successfully met Checkpoint 3.4 at Level 2 if:
- the content has been reviewed, and it has been found that where
inconsistent or unpredictable responses
are essential to its function (e.g. mystery games,
adventure games, tests, etc.), the user is warned in advance of
encountering them
- a conformance claim associated with the content asserts
conformance to this checkpoint at level 2 or level 3.
You will have successfully met Checkpoint 3.4 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- controls that look or sound the same should be designed to act the
same,
- conventions likely to be familiar to the user should be followed,
- 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.
Checkpoint 3.5 Provide methods to
minimize error and provide graceful recovery.
Success criteria
You will have successfully met Checkpoint 3.5 at the Minimum Level
if:
- if an error is detected, feedback is provided to the user identifying
the error.
You will have successfully met Checkpoint 3.5 at Level 2 if:
- the content has been reviewed
and is believed to have incorporated error prevention and recovery
methods that are considered to be effective and appropriate
- a conformance claim associated with the content asserts
conformance to this checkpoint at level 2 or level 3.
You will have successfully met Checkpoint 3.5 at Level 3 if:
- where possible, the user is allowed to select from a list of options as
well as to generate input text directly
- errors are identified specifically and suggestions for correction are
provided where possible
- checks for misspelled words are applied and correct spellings are
suggested when text entry is required.
- where consequences are significant and time-response is not important,
one of the following is true
- actions are reversible where possible
- where not reversible, actions are checked for errors in
advance.
- where not reversible, and not checkable, a confirmation is asked
before acceptance
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Guideline 4 - Understandable.
Make it as easy as possible to understand the content and controls.
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.
Checkpoint 4.1 Write as clearly and
simply as is [appropriate / possible] for the purpose of the content.
Reviewer's Note: This item is under
discussion. There is consensus for the existence of the checkpoint but not
for the form of the success criteria. We do not therefore have something for
the draft at this time. There is a list below of items that are being
explored for inclusion either as success criteria or as Advisory
Recommendations. We are also compiling a longer list (approx 50 items) of
different ideas that relate to this checkpoint.
This checkpoint is very difficult and the group is
wrestling with a number of problems. Among them:
- 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.
- There are some cases where the form is specific to the intent, (poetry,
exposition )
- Since some people can not understand the content no matter how simply
it is written, it is not possible to make any content accessible to
everyone. Therefore, we are having difficulty finding specific objective
criteria that could be applied across all types of content and sites.
Comments, suggestions and contributions to the discussion
and work on this topic are also solicited. Refer to the issues list for more
information.
Success criteria
You will have successfully met Checkpoint 4.1 at the Minimum Level
if:
- (still under construction.)
You will have successfully met Checkpoint 4.1 at Level 2 if:
- (still under construction.)
You will have successfully met Checkpoint 4.1 at Level 3 if:
- (still under construction.)
The following are additional ideas for enhancing a site along this
particular dimension:
- (still under construction.)
Partial list of items being explored for inclusion as success criteria or
advisory recommendations
- content under site control is written as clearly and simply as the
author feels [appropriate / possible] for the purpose of the content.
- the content has been reviewed and is believed to be written as clearly and simply as
is [appropriate / possible] for its intended purpose
- summaries and/or simpler forms are provided for key pages or sections
of the content.
- provide an outline or a summary for your document.
- break up long paragraphs into shorter ones, with one idea per
paragraph.
- break up long sentences into shorter ones.
- provide accurate unique page titles.
- ensure that headings and link text are unique and that they make sense
when read out of context.
- provide definitions for any jargon or specialized terminology used in
your document.
- provide explanations of figurative, metaphorical, or idiomatic uses of
language (for example, 'haven't seen you in a coons age' or 'the sight
tore my heart out').
- language should be used that your intended audience ought to be
familiar with.
- when introducing new concepts or terms, they should be defined or
annotated in language that the audience is expected to be familiar with,
or definitions or explanations should be linked to that might be easier
to understand.
Checkpoint 4.2 Supplement text with
non-text content.
Success criteria
You will have successfully met Checkpoint 4.2 at the Minimum Level
if:
- authors have included non-text content to supplement text for key pages
or sections of the site where they felt it was appropriate.
You will have successfully met Checkpoint 4.2 at Level 2 if:
- the content has been reviewed and it is believed that text has been supplemented with non-text content to the
extent deemed appropriate by the author
- a conformance claim associated with the content asserts
conformance to this checkpoint at level 2.
You will have successfully met Checkpoint 4.2 at Level 3 if:
- non-text content has
been added 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.
- a conformance claim associated with the content asserts
conformance to this checkpoint at level 3.
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
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?
Checkpoint 4.3 Annotate complex,
abbreviated, or unfamiliar information with summaries and definitions.
Success criteria
You will have successfully met Checkpoint 4.3 at the Minimum Level
if:
- acronyms and abbreviations are defined the first time they appear.
You will have successfully met Checkpoint 4.3 at Level 2 if:
- the content has been reviewed, taking into account the
additional ideas listed below, and it is believed that
complex, abbreviated or unfamiliar information has been annotated appropriately
- a conformance claim associated with the content asserts
conformance to this checkpoint at level 2.
You will have successfully met Checkpoint 4.3 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- provide a definition or link (with the first occurrence) of phrases,
words, acronyms, and abbreviations specific to a particular
community.
- provide a summary for relationships that may not be obvious from
analyzing the structure of a table but that may be apparent in a visual
rendering of the table.
- if contracted forms of words are used such that they are ambiguous,
provide semantic markup to make words unique and interpretable.
Guideline 5 - Robust.
Use Web technologies that maximize the ability of the content to work with
current and future accessibility technologies and user agents.
Checkpoint 5.1 Use technologies
according to specification.
Success criteria
You will have successfully met Checkpoint 5.1 at the Minimum Level
if:
- for markup, except where the site has documented that a specification
was violated for backward compatibility, the markup has passed validity
tests of the language (whether it be conforming to a schema, Document
Type Definition (DTD), or other tests described in the specification),
structural elements and attributes are used as defined in the
specification, accessibility features are used, and deprecated features
are avoided.
- for Application Programming Interfaces (API's), programming standards
for the language are followed.
- accessibility features and API's are used when available.
You will have successfully met Checkpoint 5.1 at Level 2 if:
- for markup, the markup has passed validity tests of the language
(whether it be conforming to a schema, DTD, or other tests described in
the specification), structural elements and attributes are used as
defined in the specification, accessibility features are used, and
deprecated features are avoided.
You will have successfully met Checkpoint 5.1 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
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?
Checkpoint 5.2 Ensure that
technologies relied upon by the content are declared and widely available.
Success criteria
You will have successfully met Checkpoint 5.2 at the Minimum Level
if:
- 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.
- Note: 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.
- the content is still usable when features not on the
required list (for
example, scripting and stylesheets) are turned off or not supported.
You will have successfully met Checkpoint 5.2 at Level 2 if:
- Technologies and features on the required list are
available in at least two independently-developed implementations.
- of at least two such implementations, it is true that the
technologies and features on the required list have been
supported by at least one prior version of the software.
You will have successfully met Checkpoint 5.2 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Checkpoint 5.3 Choose technologies
that are designed to support accessibility.
Success criteria
You will have successfully met Checkpoint 5.3 at the Minimum Level
if:
- the technology or combination of technologies chosen:
- support device independence
- include accessibility features
- have publicly documented interfaces for interoperability
- 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
- are implemented in user agents and/or proxies in the natural
language(s) of the content
You will have successfully met Checkpoint 5.3 at Level 2 if:
- (presently no additional criteria for this level.)
You will have successfully met Checkpoint 5.3 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Checkpoint 5.4 Ensure that user
interfaces are accessible or provide an accessible alternative.
Success criteria
You will have successfully met Checkpoint 5.4 at the Minimum Level
if:
- 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.
You will have successfully met Checkpoint 5.4 at Level 2 if:
- the interface has been tested using a variety of assistive technologies
and preferably real people with disabilities who use assistive
technologies to determine that assistive technologies can access all
information on the page or hidden within the page.
Reviewer's Note: It would be possible to comply with the
checkpoint without carrying out tests (either with users or with
assistive technologies). Conversely, it is possible to conduct tests, but
still fail to meet the checkpoint (with respect to assistive technologies
that were not tested, for example). Should this success criterion be
deleted?
- device-independent access to functionality is provided
- accessibility conventions of the markup or programming language (API's
or specific markup) are used
You will have successfully met Checkpoint 5.4 at Level 3 if:
- (presently no additional criteria for this level.)
The following are additional ideas for enhancing a site along this
particular dimension:
- (presently no additional criteria for this level.)
Appendix A: Glossary
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.
Appendix B: Explanation of Conformance Levels
and Success Criteria
The Three Levels of Conformance
The effect of the three levels of conformance defined in these guidelines may be
characterized as follows.
If Web content satisfies a checkpoint at the first conformance level
(i.e., "minimum"), then the barriers to access which the checkpoint was
designed to address will have been minimally overcome for at least
some people with disabilities. The quality of access thus provided is
not necessarily high, and there may well be people with disabilities to whom
the content remains inaccessible due to issues relevant to the
checkpoint, despite the attainment of minimal conformance.
At level 2, a more demanding standard of access is achieved. Often,
this is assured by requiring, in success criteria at this level, that
the access-related features of the content be reviewed for quality and
completeness. In undertaking such reviews, it is recommended, though
not required for purposes of conformance, that consistent processes be
followed and that, if possible, these should include evaluation of the
content by users with disabilities, for example as part of a testing
procedure. To guide designers and evaluators in developing content and
reviewing it for accessibility, the additional ideas section
that appears under most checkpoints, lists various factors which
greatly enhance the level of access provided. These factors are not in
themselves testable (see below), but they should be taken into account
in designing content and assessing its quality, as required by the
success criteria at level 2 of the guidelines.
At level 3, the highest possible standard of access is attained
along the dimension identified in the checkpoint. The purpose of
implementing a checkpoint at level 3 is typically to optimize the
content for use by people with specific requirements or expectations.
For this reason, there may be particular types of content for which
conformance to a given checkpoint, at level 3, is not feasible.
Nevertheless, implementors are strongly encouraged to meet level 3
success criteria wherever possible. Moreover, there are some people
with disabilities who may only be able to access the content if it
conforms to level 3 of one or more particular checkpoints. [Perhaps we
need an example here?]
Testability
All success criteria in these guidelines are testable,
according to the following definition. A success criterion is
considered testable if
- There exist, at least in principle, automated testing procedures which can reliably
determine whether or not the requirement has been satisfied
or
- It is believed that at least ninety percent of informed human
evaluators, in assessing content, would agree as to whether the
requirement has been met.
There nonetheless exist requirements, or factors of importance to
accessibility, which are not testable according to the above
definition. These have been placed in the additional ideas
sections of relevant checkpoints, and should be taken into account not
only in developing Web content, but also, as noted above, in evaluating its degree of
accessibility to people with disabilities.
Appendix C: Contributors
Participants in the
WCAG Working Group
Appendix D: The differences between WCAG 1.0 and WCAG
2.0
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, when it eventually becomes a W3C Recommendation:
- will be more efficiently organized,
- may adjust the priority of some checkpoints,
- may modify, remove, or add requirements due to changes in Web
technologies since the publication of WCAG 1.0,
- will incorporate the Errata from WCAG 1.0,
- will reflect the experience gained in implementing WCAG 1.0.
For a checkpoint by checkpoint comparison, refer to the Checkpoint Mapping Between WCAG
1.0 and the WCAG 2.0 Working Draft.
Improvements in WCAG 2.0
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:
- Ensure that requirements may be applied across technologies
- Ensure that the conformance requirements are clear
- Ensure that the deliverables are easy to use
- Write to a more diverse audience
- Clearly identify who benefits from accessible content
- Ensure that the revision is "backward compatible" with WCAG 1.0
For more information about the intended improvements in WCAG 2.0 Working
Draft, please refer to Requirements
for WCAG 2.0.
Appendix E: References
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.