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 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.
This document outlines design principles for creating accessible Web
content. 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:
- 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.
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.
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)
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.
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 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.
Reviewer's Note: As we publish this
Public Working Draft of WCAG 2.0, the WCAG WG is in the midst of addressing a
variety of issues with conformance. This section outlines the conformance
structure used throughout this document and advises the reader that the WCAG
WG has discovered a variety of issues with this scheme. The issues are
outlined for the reader's consideration. Feedback, comments, and proposals
are encouraged. Further information about current proposals and recent discussion is available.
This draft uses the following three levels of conformance:
-
Minimum Level
- includes success criteria for the checkpoint that address key
problems and are applicable across the broad range of Web content and
sites. Conformance at this level will substantially overcome the
barriers for many people with disabilities, but there will be people
with disabilities who will still not be able to access the content. No
claim of conformance can be made unless the minimum level of
conformance is achieved for all checkpoints.
-
Level 2
- includes additional success criteria that increase the accessibility
of Web content, but that are more difficult to implement on Web content
in general or on specific types of content.
-
Level 3
- represents the highest level of conformance in WCAG 2.0. It includes
success criteria that may be very difficult as well as criteria that
may not be possible at all for some types of content or some Web
architectures.
If the above conformance levels are used, the rules regarding conformance
claims would be:
- No conformance claim of any type may be made unless all MINIMUM Level
success criteria have been met for all checkpoints in WCAG 2.0.
- If all of the checkpoints have been met at the MINIMUM Level, but only
some of the criteria for Level 2 have been met, then a conformance claim
at "LEVEL 1+" can be made.
- If all success criteria (for all checkpoints) are met at the MINIMUM
Level and Level 2, then a claim conformance at "Level 2" can be made.
- If all of the success criteria for (for all checkpoints) are met at the
MINIMUM and Level 2, as well as some, but not all of the criteria for
Level 3, then a conformance claim can be made at "Level 2+".
- If all success criteria for all Levels have been met, then a
conformance claim at "Level 3" can be made.
For conformance claims of Level 1+ and Level 2+, it is recommended (but
not required) that sites report specifically which criteria they have met
within each of the guidelines and checkpoints. WCAG 2.0 Techniques documents
will provide examples that show how to report which success criteria have
been met from Levels 2 and 3.
All conformance claims must include (at minimum):
- The version of the guidelines to which a conformance claim is made and
the URI of the guidelines document.
- The scope of the conformance claim. The scope describes which parts of
a site or application are included in the claim.
Reviewer's Note:
Should exclusions be allowed for certain types of
content, such as third-party or copyrighted material that is being
reprinted? How does one define scope? Is it an end-to-end process that
the user should be able to complete? Is it a path through accessible
content?
- The level at which conformance is claimed.
- The date the conformance claim was made.
Sites that currently conform to WCAG 1.0 that want to shift towards WCAG
2.0 will want to capitalize on past accessibility efforts. A qualified
conformance statement could allow them this flexibility. For example, a
conformance claim might include the following statement, "Materials created
or modified before 24 April 2003 conform to WCAG 1.0. Materials created or
modified on or after 24 April 2003 conform to WCAG 2.0."
Reviewer's Note: In some instances,
the WCAG 2.0 Working Draft may be easier to conform to than the WCAG 1.0
Recommendation. However, the WCAG 2.0 Working Draft requires a minimum level
of conformance to each checkpoint and this may make some parts of WCAG 2.0
harder to conform to than WCAG 1.0. For example, in WCAG 1.0 checkpoints
related to providing navigation mechanisms are priority 2 and 3, while in
this WCAG 2.0 Working Draft there are several minimum level success criteria
for navigation mechanisms. This might be resolved by merging some checkpoints
and moving some of the success criteria to the Second Level rather than the
Minimum.
The WCAG WG is committed to making WCAG 2.0
backwards compatible with WCAG 1.0.
Reviewer's Note: As the WCAG WG has discussed conformance, there has been
concern about requiring changes in style and content to meet accessibility
requirements. This section summarizes these issues.
The primary strategy to improve accessibility has been to supplement
content with additional information. For example, text equivalents and
structural markup enable a user agent or assistive technology to make the
content accessible to the user. Some of the current checkpoints require
authors to change the manner in which their primary content is expressed or
presented. For example, checkpoint 1.4 (emphasize structure through
presentation), checkpoint 3.1 (provide structure), 4.1 (write clearly) and
4.2 (supplement text with illustrations) all have requirements at the minimum
level. There are two issues with altering the primary content rather than
supplementing it:
- it potentially limits the author's freedom of expression,
- it is not appropriate or permissible in some circumstances, e.g., in
the case of legal documents, and historical, artistic, and literary
works.
Should minimum level success criteria that impose constraints on the
author's means of expression be shifted to level 2? We have discussed a
variety of potential future technologies (e.g., metadata). However, those
tools are not widely deployed and the schema still in development. How should
we address the tension between solving current problems without constraining
the author's freedom of expression? How do we address the opportunities that
emerging technologies such as metadata will provide? Can we achieve some of
this with semantic markup and next generation assistive technologies?
Recent proposals significantly redefine the three levels. With the
proposed priority schemes, success criteria that require changes in content
are no longer in the minimum level. However, the following issues remain to
be addressed:
- Is the minimum set limited to those success criteria that can be
accomplished via markup or code?
- Can we require anything in the minimum set that might impact someone's
freedom of expression?
- Is the minimum set tied to what is possible today while other levels
are more open to what will be possible in the future?
- Is the minimum set only those success criteria that can be tested with
an automatic tool?
- Is the minimum set not only success criteria that have the greatest
impact on accessibility but also those that are most feasible to do
today?
- Do the different groupings represent a hierarchical relationship? If
not, is "group" or "category" a more appropriate term than "level?"
- Will we have three priority levels or will they collapse into two?
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.
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".
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.
- 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).
- 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)
- (presently no additional criteria for this level.)
- (presently no additional criteria for this level.)
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.
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), 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 covered in checkpoint 5.4.
- 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 by their assistive technology.
- Individuals who are blind or deaf-blind can have the information
presented in braille.
- Example 1: an image used as a button. (short description of function)
A right arrow icon is used to link to the next slide in a slide show. The
text equivalent is "Next Slide," so that what is read by a screen reader
would be "link: Next Slide."
- Example 2: a data chart. (short label + longer description)
A bar chart compares how many widgets were sold in June,
July, and August. The short label says, "Figure one - Sales in June, July and August." The longer description identifies the type
of chart or graph, provides a high-level summary of the data comparable to
that available from the chart or graph, and lists the data themselves.
- Example 3: an animation. (short label + longer description)
An animation shows how to tie a knot. The short label says, "An animation
showing how to tie a square knot." The longer explanation describes the
hand movements needed to tie the knot.
- Example 4: an audio file of a speech. (short label + transcript)
An audio file is embedded in a Web page. The short label says,
"Chairman's speech to the assembly." A link to a text transcript is
provided immediately after the clip.
- Example 5: an audio file of a symphony. (short label)
An audio file is embedded in a Web page. The short label says,
"Beethoven's 5th Symphony performed by the Vienna Philharmonic
Orchestra."
- an audio description is provided of all significant visual information in scenes, actions and events that cannot be perceived from the sound track alone.
- Note: 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. It may also be impossible or inappropriate to freeze the audio/visual program to insert additional audio description.
- all significant dialogue and sounds are captioned
exception: 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.
- 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), either provide an equivalent that conforms to checkpoint 1.1 (e.g., an ongoing update of weather conditions) or link to an equivalent that conforms to checkpoint 1.1 (e.g., a link to a weather Web site).
- 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.
- 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 text document that merges all audio descriptions and captions into a collated script (that provides dialog, important sounds and important visual information in a single text document) is provided.
- captions and audio descriptions are provided for all live broadcasts
which provide the same information.
- The presentation does not require the user to read captions and the visual presentation simultaneously in order to understand the content.
- (presently no additional criteria for this level.)
A time-dependent presentation is a presentation
which
- 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.
Media equivalents
present essential audio
information visually (captions) and essential video information
auditorily (audio descriptions).
- captions are text equivalents of auditory
information from speech, sound effects, and ambient sounds that are
synchronized with the multimedia presentation.
-
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.
- 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 requiring people to use a single sense to follow two or more things at the same time may 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 (e.g. a football game). Where possible, provide content so that it does not require tracking multiple simultaneous events with the same sense, or give the user the ability to freeze the video so that captions can be read without missing the video.
- Example 1: a movie clip with audio description and
captions.
A clip from a movie is published on a Web site. In the clip, a child is
trying to lure a puppy to the child's bedroom by laying a trail of
crumbs. The child mumbles inaudibly to himself as he lays the trail. When
not watching the video, it is not obvious that he is laying a trail of
crumbs since all you hear is the mumbling. The audio description that is
interspersed with the child's mumbling says "Charlie lays a crumb on each
stair leading to his room." The caption that appears as he mumbles is,
"[inaudible mumbling]."
- Example 2: a video clip of a news story.
A video clip accompanies a news story about the recent flooding in a
major city. The reporter describes what is seen, for everyone. No audio
description is necessary. The captions display what the reporter is
saying.
- Example 3: a silent animation.
An animation shows a pantomime climbing a ladder. There is no audio track
for this animation. No captions or audio description are required.
Instead, a text equivalent is provided as described in checkpoint
1.1.
- 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
- (presently no additional criteria for this level.)
- (presently no additional criteria for this level.)
- (presently no additional criteria for this level.)
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.
- Example 1: a multi-column document.
A document is marked up with headings, paragraphs and other structural
features. It is presented visually in three columns. The markup that
creates the columns is separate from the markup that specifies the
logical structure of the document.
- Example 2: a scrolling list of stock prices.
Current stock quotes are scrolled horizontally across the screen. The
data are separate from the methods used to scroll the text across the
page.
- Example 3: a 3-dimensional site map.
A custom user interface renders 3D visualizations of the pages on a site
and how they relate to one another from a data source. Any hierarchical
relationships, groupings, cross-references, etc. would originate in the
data source so that alternate interfaces could be rendered (from the same
source) that expose the structure of the site in an accessible form. (See
also checkpoint 5.4)
- Example 4: a list that allows users to sort information on a
page according to preference.
A script allows a user to rearrange a categorical listing of music files
by date, artist, genre, or file size. The script updates both the
structure and the presentation accordingly when generating alternate
views.
- the structural elements present have a different visual appearance or
auditory characteristic than the other structural elements.
- the structural emphases are chosen to be distinct for different major
display types (e.g. black and white, small display, mono audio
playback).
- 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.
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.
Presentation that emphasizes structure:
- enables users with cognitive and visual disabilities to orient
themselves within the content,
- enables all users to move quickly through the content and notice major
content divisions
- enables all users, but particularly users with visual or cognitive
disabilities to focus on important content,
- enables all users, but particularly users with visual or cognitive
disabilities to distinguish the different types of content.
- Example 1: documentation for a product.
Identifying chapters in the structure of a book is appropriate and
accepted use of labeling the structure. Within the chapters, headings
identify (label) changes in context and highlight ideas contained in the
following text. Subtle differences between the appearance of the chapter
title and the section headings helps the user understand the hierarchy
and relationship between the title and headings. The only difference
might be font size and margin indentation when presented visually, and
spoken in a difference voice or preceded by a sound when presented
auditorily.
- Example 2: a data table.
Groups of rows or columns are labeled with headers.
- Example 3: an audio presentation.
An audio rendering of a document, generated according to a style
sheet, uses a different, more formal voice to read
titles and headers so the listener can easily identify the words as a
title and not part of the running text.
- text content that is presented over a background image or pattern is
implemented using mechanisms that allow the user to display the text without the background image or pattern.
- when text content is presented over a background image or pattern, the text
is easily readable when the page is viewed in 256 grayscale.
- 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).
- audio content does not contain background sounds OR the background sounds
are at least 20 db lower than the foreground audio content.
- text content is not presented over a background image or color OR the
colors used for the text and background or background image pass the
following test:
- no tests/algorithms are available at this time
Reviewer's Note: The working group is seeking an algorithm that measures contrast in a way that is accurate and testable enough that we could include it in the guidelines. One algorithm, which comes from the Techniques For Accessibility Evaluation And Repair
Tools document, is currently under consideration for inclusion in the techniques, but the group has not yet found something that is specific enough to be included at the guidelines level.
- (presently no additional criteria for this level.)
- Individuals with low vision can easily make out characters in the
content even if they don't have the wide field of view used by fully
sighted persons to separate text from background images.
- Individuals with hearing impairments that limit their ability to hear
all of the frequencies of speech can make out the words from the sounds
they can hear because they are not mixed with residual sounds from the
music.
- Example 1: a background image on a page.
A background image and text are arranged so that there is no image behind
the text or the image is so faint that the difference between the darkest
part of the image and the text (which is dark) meets the standard
foreground/background contrast requirements. The image behind the text
also does not contain lines that are about the same width as the
characters so they do not interfere with character recognition.
- Example 2: speech over background sounds.
Because speech is often naturally mixed with background sounds (movies,
live news etc) and cannot be easily removed or separated, captions are
provided (under checkpoint guideline 1.2) to make dialog understandable.
However not all people can see or read the captions. Where speech is mixed
or recorded so that it is at least 20 db above any background sounds people
do not need to rely on captions to understand the dialog.
- text in the content is provided in Unicode or sufficient information is
provided so that it will be automatically mapped back to Unicode.
- 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.
- the primary natural language of the content is identified at the page
level.
- (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.
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.
- Example 1: a French phrase in an English sentence.
In the following sentence, "And with a certain je ne sais quoi, she
entered both the room, and his life, forever." the French phrase "je ne
sais quoi" is marked as French. Depending on the markup language, English
may either be marked as the language for the entire document except where
specified, or marked at the paragraph level.
- Example 2: an acronym in a page title.
In the following heading, "People of the W3C." the acronym "W3C" is
marked as an acronym. Because it has been marked appropriately, the user
agent would be able to speak the letters of the acronym one at a time
rather than attempting to pronounce it as though it were a word.
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.
- all of the functionality of the content where the functionality or
its outcome can be expressed concisely in words is operable at a minimum
through a keyboard or keyboard interface.
- Note: refer to checkpoint 5.3 for information
regarding user agent support.
- wherever a choice between event handlers is available and supported,
the more abstract event is used.
- (presently no additional criteria for this level.)
- (presently no additional criteria for this level.)
A keyboard interface is the point where the application accepts any
input that would come from the keyboard (or optional keyboard).
- 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.
- Example 1: operation with multiple input devices.
The content relies only on focus-in, focus-out, and activation
events; these are defined in the API of the environment for which the
content is written, and are intended to be operable by a variety of input
devices, including pointing devices, keyboards and speech input
systems.
-
Example 2: examples of Web content that would and would not be operable from a keyboard or keyboard interface
- If it's written to be operable from a computer keyboard, it conforms. (because it is operable from the keyboard.)
- If it's written to be used on a device that doesn't usually have a keyboard such as a cell phone and but it can be controlled by an optional keyboard for that device, it conforms. (A person who needs a keyboard - or alternate keyboard - can use it to control the application.)
- If it's written to be used with a device that doesn't have a keyboard, but it could also be used by similar devices that do and it would work with their keyboard, it conforms. (A person who needs a keyboard would not buy the device without the keyboard. That device may itself not be considered accessible. But the content can be controlled from a device with a keyboard and therefore conforms to this checkpoint.)
- If it's written to work with devices that do not have keyboards and it can not be used by any other devices that do have keyboards, then it does not conform. (It cannot be accessed via keyboard.)
- 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).
- (presently no additional criteria for this level.)
- activities are designed so that time limits are not an essential part
of the activity (e.g. competition, testing, etc. are not time based).
- (presently no additional criteria for this level.)
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:
- automatic refresh,
- redirection,
- blinking or scrolling text
- dialog that disappears after a short period
- shutdown or deactivation of page if activity is not received in a set
amount of time
- Example 1: blinking text.
Client-side scripting is used to create blinking text. The user can
deactivate the use of scripting in his or her browser or override the use
of scripts with a user style sheet.
- Example 2: a news site that is updated regularly.
A news site causes its front page to be updated every 1/2 hour. The front
page contains minimal text and primarily consists of links to content. A
user who does not wish the page to update selects a checkbox. The
checkbox is in the "user preferences" portion of the site which is one of
the first links on each page.
- 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.
- 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.
- (tougher test - that would make pages pass with even slower equip.
Equip might be old or just slow for other reasons)
- (presently no additional criteria for this level.)
- (presently no additional criteria for this level.)
Reviewer's Note: Trace is currently in
the process of exploring an automated flicker testing tool.
- Individuals 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.
- Individuals 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 and the ability to efficiently move about the site, document or application.
- the following minimum structure elements are present.
- titles on major sections of long documents
- paragraphs
- 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
- 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.
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?
The structure of content represents changes in
context. For example,
- 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.
- 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."
When the logical structure is provided in markup or a data model,
- Users with physical disabilities can use structure to more easily jump
between paragraphs, chapters, sections etc.
- Users with cognitive disabilities can use structure (chapter titles,
headers, etc.) to provide more context for the text that follows them.
They also provide warning of a change in context and reorient the user to
the new focus.
- Users with blindness or low vision can jump from header to header to
get an overview or to more quickly "skim" to the section they are
interested in.
- Readers with low vision can sometimes (depending on display technology)
change how chapter titles and headers are displayed to make them more
visible -and easier to use when skimming the document.
- the content can be presented on a variety of devices because the device
software can choose only those elements of the content that it is able to
display and display them in the most effective way for that device.
- Example 1: a physics dissertation.
A dissertation contains well-defined sections such as "Abstract," "Table
of Contents," "Chapter 1," etc. The pieces in each section (paragraphs,
subheadings, quotes) are denoted with structural markup.
- Example 2: a scalable image of a bicycle.
Lines and a circle (spokes and rim) are grouped into a "wheel." Lines in
a triangle that attach to each wheel are grouped into a "frame."
- Example 3: user interface.
User interface controls are divided into organized groups.
- 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.
- 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.
- 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.
- (presently no additional criteria for this level.)
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
- 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.
- Individuals with cognitive disabilities may find it easier to ask for
what they want than to deduce its location from categorical choices.
- Individuals 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.
- key orientation and navigational elements are generally found in one or
two locations or their locations are otherwise predictable.
- 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
- (presently no additional criteria for this level.)
- 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
Presentation includes, but is not limited to:
- position,
- font, font size,
- color
- voice and voice characteristics
- sounds
- white space
- 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.
- 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.
- 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
- 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
- (presently no additional criteria for this level.)
- 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.
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.
- Individuals who are unable to detect extreme changes in context or may
not realize that the context has changed are less likely to become
disoriented while navigating a site. This applies to people in the
following ways:
- Individuals who are blind or have low vision may have difficulty
knowing when a visual context change, such as a new window popping
up, has occurred. In this case, warning users of context changes in
advance minimizes confusion when the user discovers that the back
button no longer behaves as expected.
- Using captions to note changes in speaker is beneficial for
individuals who are deaf or hard of hearing and who may be unable to
discern changes in speaker for audio-only presentations.
- Some individuals with low vision, with dyslexia and who have difficulty
interpreting visual cues may benefit from additional cues in order to
detect extreme changes in context.
Note: Providing consistent and predictable responses to
user actions is important feedback for the user. This lets them know that
your site is working properly and encourages them to continue interacting
with the content. When the user receives an unexpected response, they might
conclude that something is wrong or broken. Some people might get so confused
they will not be able to use your site.
- Example 1: a form to deactivate pop-up windows.
A checkbox is provided on a page of links to let the user select whether
they want the resultant pages to appear in new windows or not.
- Example 2: a warning given before a pop-up window.
At the end of a news story, several links are provided for more
information. At the beginning of each link is an icon of an arrow with
the text equivalent, "Link will open in new window."
-
Example 3: frames that do not track history making the back
button behave unexpectedly.
-
Example 4: forms.
Reviewer's Note: Some of these examples
are very brief. Should they be expanded and clarified with further
details?
- if an error is detected, feedback is provided to the user identifying
the error.
- the content has been reviewed
and is believed to have incorporated error prevention and recovery
methods that are considered to be effective and appropriate
- 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
- (presently no additional criteria for this level.)
- Individuals with writing disabilities and people with dyslexia often
have difficulty writing text in forms or other places that need text
input.
- Individuals with speech disabilities might not be recognized properly
in voice input applications.
- Example 1: a search engine.
A search engine is provided with a variety of search options for
different skill levels and preferences. It includes a spell checker and
offers "best guess" alternatives, query-by-example searches, and
similarity searches.
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.
This checkpoint lists ideas to help you review content for clarity.
Plain language specialists around the world promote many of these ideas.
The following items are not presented as success criteria, however, or
as an attempt to impose editorial style. Rather, they are elements to
consider as you review writing. They reflect the idea that accessibility
begins with understanding.
Reviewer's Note: Since there has been concern about requirements at the minimum level that would require content to be presented in a particular way, this checkpoint has been worded in a way that requires authors to "consider" a list of criteria and review their content with that list in mind. Is this difference clear in comparison to other checkpoints?
- familiarity of terms and language structure
- reasonableness of length and complexity of sentences
- coherence of paragraphs (and sensibility in length)
- clarity of headings and linked text when read out of context
- accuracy and uniqueness of page titles
- care in the use of all-capital letters where normal sentence case
might increase comprehension
- use of sentence structures that increase understanding
- such as active voice in languages where this form helps convey
information
- length of noun phrases
- strings of no more than three or four nouns are easiest to understand
- 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."
- 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"
- complexity of verb tenses
- do the tenses used in a document seem overly complicated?
- intelligibility of verb phrases
- familiarity of idioms or slang
- logic in the order and flow of information
- consequences of ambiguity or abstraction
- improved readability of vertical lists might offer in place of long paragraphs of information
- use of summaries to aid understanding
- thoroughness in the explanation of instructions or required actions
- consistency in the use of names and labels
- 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)
- 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
- new material is tested with potential users for ease of accessibility
- a controlled language is used
- support is given for conversion into symbolic 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.
- All users, especially those with cognitive, learning, and/or reading
disabilities benefit from the use of clear and simple writing. 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.
- authors have included non-text content to supplement text for key pages
or sections of the site where they felt it was appropriate.
- 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
- 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.
- (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?
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.
- Example 1: a description of a process.
A page describes how to learn to play soccer. Each step in learning the
fundamentals of the game is illustrated with a photograph of a player
doing what is described in the text.
- Example 2: a concrete concept.
The primary concept on a page is concrete. It is discussing Mt. Pinatubo.
It includes both a description of the 1991 eruption as well as photos of
the eruption and the aftermath. It links to another site that contains
video and another site that contains a 3D simulation of what happened
underneath the crust and within the volcano during the eruption.
- Example 3: child's report of school trip.
A child went with her school on a trip to a bicycle manufacturing plant.
She wrote a report for her family and friends to post to the Web. In the
report, she includes the company logo as well as a picture of a bicycle
on the assembly line. She links to the company Web site for more
information. She includes photos she took of the plant.
- Example 4: stock trading data.
A news site is comparing the performance of the economy from 3rd quarter
of this year with 3rd quarter from the last 3 years. They compare prices
of the most popular stocks. They present the data in a bar graph with a
link to the raw data they used to create the bar graph.
- Example 5: history of music.
A grandfather's hobby is listening to and playing music. He creates a Web
site that includes examples of many different types of music and musical
instruments. When describing specific types of music, he links to a short
sound clip.
- acronyms and abbreviations are defined the first time they appear.
- 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
- (presently no additional criteria for this level.)
- 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.
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.
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 completely
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.
- 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.
Reviewer's Note:The following two success criteria seem to overlap with checkpoint 5.4. There is an open question about whether they should be deleted since Checkpoint 5.4 covers programmatic interfaces.
- for Application Programming Interfaces (API's), programming standards
for the language are followed.
- accessibility features and API's are used when available.
- 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.
- (presently no additional criteria for this level.)
- (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?
- 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.
- Example 1: structural elements.
Throughout a Web site, structural elements are not used for purposes of
presentation. Likewise, presentational elements are not used for purposes
of structure.
- Example 2: accessible API's.
A Java applet uses the accessibility API defined by the language. Refer
to the IBM Guidelines
for Writing Accessible Applications Using 100% Pure Java.
- 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.
- 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.
- (presently no additional criteria for this level.)
- (presently no additional criteria for this level.)
A technology is a
- markup or programming language
- application Programming Interface (API)
- or communication protocol
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.
Benefits of determining and documenting baseline user agent
requirements:
- Individuals can identify (either through site documentation or
automatically through metadata) whether or not they are likely to be able
to use a site. In conjunction with a search engine or a proxy server,
this could be used to automatically filter out sites a user can not
access or to automatically filter to the top sites that would be most
usable.
- Requiring sites to document their baseline will cause them to evaluate
assumptions about user agents and will minimize the number of sites that
are inadvertently inaccessible because they are unaware of backward
compatibility issues.
Benefits of designing for backward compatibility:
- Individuals who must use alternative browsing technologies and devices
will be able to access the content.
- Individuals who can not afford or otherwise do not have access to newer
technologies also benefit from backward compatibility in that they will
not need to purchase upgrades or equipment as often.
- Example 1: an online store.
By documenting minimum user agent requirements, the store makes it
possible for people using particular technologies to determine if they
are going to have trouble using the store or its checkout mechanism
without having to go through the entire process of shopping and checkout
only to find out that they are unable to complete their transaction at
the end. They can, therefore, shop at stores they can be successful
at.
- Example 2: an Intranet site.
A large company was concerned about the ability to address individuals at
many diverse sites that have different technology bases. They have,
therefore, created two versions of their content and documented the
requirements for each, making it easy for individual sites to determine
which version would work for their technologies.
- 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
- (presently no additional criteria for this level.)
- (presently no additional criteria for this level.)
- (presently no additional criteria for this level.)
- Authors who utilize technologies designed to support accessibility
will:
- encounter fewer challenges when implementing these guidelines
- avoid the need to create custom solutions and workarounds to
address accessibility concerns
- avoid the need to provide accessible alternate versions for content
rendered in a technology that does not fully address these
guidelines
- 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.
- 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
- (presently no additional criteria for this level.)
- (presently no additional criteria for this level.)
Reviewers Note: There are a number of open issues and questions related to this checkpoint. Some examples include:
- How can we provide guidelines related to this checkpoint for interactive content?
- How should WCAG 2.0refer to UAAG 1.0?
- How do other applications (ex. Java, PDF and Flash) fit into UAAG?
- Individuals who rely on assistive technologies to access the Web will
be able interact with the content.
- Individuals who access the Web with older technologies or alternative
browsing devices such as PDAs and cell phones also benefit from the
inclusion of accessible alternatives to custom user interfaces.
The WCAG WG has not tackled the definitions of the terms that we are using
and we sometimes use terms inconsistently. We need to coordinate our terms and
definitions with the WAI Glossary. We 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. 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.
- text equivalent
- Non-text content
- time-dependent presentation
- Media equivalents
- captions
- audio descriptions
- Content
- Presentation
- Structure
- Natural languages
- keyboard interface
- Real-time events
- competitive activity
- structure
- site navigation mechanism
- Presentation
- Mechanisms that cause extreme changes in context
- Controlled languages
- Non-text content
- complex
- unfamiliar
- technology
- feature
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, 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.
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.
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.