Copyright © 2005 W3C ® ( MIT , ERCIM , Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.
This document, "Understanding WCAG 2.0," is an essential guide to understanding and using "Web Content Accessibility Guidelines 2.0" [WCAG20]. It is part of a series of documents which support WCAG 2.0.
WCAG 2.0 establishes a set of "success criteria" to define conformance to the WCAG 2.0 Guidelines. A success criterion is a testable statement that will be either true or false when applied to specific Web content. "Understanding WCAG 2.0" provides detailed information about each success criterion including its intent; the key terms that are used in the success criterion; examples of Web content that meets the success criteria using various Web technologies (for instance, across HTML, CSS, XML) and common examples of Web content that does not meet the success criterion. Finally, this document also explains how the success criteria in WCAG 2.0 help people with different types of disabilities.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This draft is the First Public Working Draft of "Understanding WCAG 2.0." The Web Content Accessibility Guidelines Working Group (WCAG WG) considers this document to be essential for understanding the success criteria in the Web Content Accessibility Guidelines 2.0 (WCAG 2.0), and encourages feedback on this draft. Please note that the contents of this document are informative (they provide guidance), and not normative (they do not set requirements for conforming to WCAG 2.0).
The Working Group particularly welcomes feedback on the following questions:
In general, does this document help you understand what WCAG 2.0 is, and how to use it?
Does this document adequately clarify each success criterion? If not, what additional clarification is needed?
In addition, the Working Group has not yet had time to list all available techniques for conforming to WCAG 2.0, but intends for the techniques to be as comprehensive as possible. Therefore, the Working Group welcomes contributions of additional techniques for consideration for inclusion in this document. Please submit these in the same manner as other comments, as described below.
Please note that the format of this document is still in transition; the Working Group plans to create separate files for each success criterion, and to link to relevant techniques providing sample code. The Working Group is also developing a navigation structure that will make it easy to move between the various documents in the series of supporting WCAG 2.0 documents.
Please send comments by 21 December 2005 to public-comments-wcag20@w3.org. The archives for this list are publicly available. Archives of the WCAG WG mailing list are also publicly available.
Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress. This document will be published as a W3C Working Group Note at the time that WCAG 2.0 becomes a W3C Recommendation.
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.
1.1.1 For non-text content that is used to convey information, text alternatives identify the non-text content and convey the same information. For multimedia, provide a text-alternative that identifies the multimedia. For live audio-only and live video-only, conform to success criterion 1.1.5. (Level 1)
Note: For requirements for synchronized alternatives for multimedia refer to Provide synchronized alternatives for multimedia.:
non-text content content that communicates ideas, data, facts information and is not text.
Programmatically determined text that is used in place of non-text content or text that is used in addition to non-text content and referred to from the programmatically determined text.
Content that is not represented by a Unicode character or sequence of Unicode characters when rendered in a user agent according to the formal specification of the content type. This includes ASCII Art, which is a pattern of characters.
For the purposes of these guidelines, multimedia refers to combined audio and video presentations. It also includes audio-only and video-only presentations that include interaction.
The intent of this success criterion is to make information conveyed by non-text content such as charts, diagrams, audio recordings, pictures, and animations available in a form that can be rendered through any modality (for example, visually, auditorily or tactilely). Providing text alternatives allows the information to be rendered in a variety of ways by a variety of user agents. For example, a person who cannot see a picture can have the text alternative read aloud to them using synthesized speech. A person who cannot hear an audio file can have the text alternative displayed so that he or she can read it.
Labeling multimedia presentations allows users to determine whether or not they want to play it. (Since conforming multimedia has built-in audio descriptions and captions, a full text alternative is not necessary).
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.1.1.
Instructions: Select the situation below that matches your content. Beneath it are the option(s) that are known and documented to be sufficient for that situation. For the technology-specific techniques, see the options for the technology you are using listed immediately below.
Providing short text alternatives using a technology-specific technique listed below.
Providing short text alternatives using a technology-specific technique listed below AND one of the following techniques for long description:
Providing long descriptions using a technology-specific technique listed below.
The following are common mistakes which are considered failures of this success criterion by the working group.
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
People who are blind, have low vision, have cognitive disabilities can have text alternatives read aloud to them by assistive technology.
People who have trouble reading text may use tools that both read text aloud and highlight the words as they are read. In some cases, it may be difficult for someone to recognize visual information and the text alternative may help him or her understand the purpose of the non-text content.
People who are deaf, are hard of hearing, or who are having trouble understanding audio information for any reason can read the text presentation or have it translated and presented as sign language by assistive technology.
People who are deaf-blind can read the text in braille.
Additionally, text alternatives support the ability to search for non-text content and to repurpose content in a variety of ways.
In the examples below, a single piece of non-text content is used in different contexts that require different text alternatives.
A data chart
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, provides a high-level summary of the data comparable to that available from the chart, and provides the data in a table.
An audio recording of a speech (no video)
The link to an audio clip says, "Chairman's speech to the assembly." A link to a text transcript is provided immediately after the link to the audio clip.
An animation that illustrates how a car engine works
An animation shows how a car engine works. There is no audio and the animation is part of a tutorial that describes how an engine works. All that is needed is a description of the image. From "How car engines work: Internal combustion"
A traffic Web camera
A Web site allows end-users to select from a variety of Web cameras positioned throughout a major city. After a camera is selected, the image updates every 2 minutes. A short text alternative identifies the Web camera as, "traffic Web camera." The site also provides a table of travel times for each of the routes covered by the Web cameras. The table is also updated every 2 minutes.
A photograph of an historic event in a news story
A photograph of two world leaders shaking hands accompanies a news story about an international summit meeting. The text alternative says, "President X of Country X shakes hands with Prime Minister Y of country Y."
A photograph of an historic event in content discussing diplomatic relationships
The same image used in a different context intended to explain nuances in diplomatic encounters. The image of the president shaking hands with the prime minister appears on a Web site discussing intricate diplomatic relationships. The first text alternative reads, "President X of country X shakes hands with Prime Minister Y of country Y on January 2, 2009." An additional text alternative describes the room where the leaders are standing, the expressions on the leaders' faces, and identifies the other people in the room. The additional description might be included on the same page as the photograph or in a separate file associated with the image through a link or other standard programmatic mechanism.
An audio recording
The Web page described in the previous example includes a link to an audio recording of the leaders' press conference. The page also links to a text transcript of the press conference. The transcript includes a verbatim record of everything the speakers say. It identifies who is speaking as well as noting other significant sounds that are part of the recording, such as applause, laughter, questions from the audience, and so on.
Excerpts from the NBA Tape Recording Manual, Third Edition. Information on describing complex images to people who are blind.
1.1.2 For non-text content that is functional, text alternatives serve the same purpose as the non-text content. If text alternatives can not serve the same purpose as the functional non-text content, text alternatives identify the purpose of the functional non-text content (Level 1)
non-text content that is capable of performing one or more actions in response to user input and is not text.
Note: This includes, but is not limited to, image-based submit buttons, applets, and embedded programmatic objects.
Programmatically determined text that is used in place of non-text content or text that is used in addition to non-text content and referred to from the programmatically determined text.
The intent of this success criterion is to ensure that the function of non-text content, such as images used as submit buttons, is available in text form if at all possible. If it is not possible to make the function available in text, then the function is identified in text.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.1.2.
Instructions: Select the situation below that matches your content. Beneath it are the option(s) that are known and documented to be sufficient for that situation. For the technology-specific techniques, see the options for the technology you are using listed immediately below.
Providing a text alternative that serves the same purpose as the non-text content, using one of the technology-specific techniques below.
Providing a text alternative that identifies the purpose of the functional non-text content, using one of the technology-specific techniques below.
The following are common mistakes which are considered failures of this success criterion by the working group.
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
Individuals who blind or deaf blind and using a screen reader or braille display cannot always access the functional non-text content. The text alternatives allow them to access the functionality of the content.
In the examples below, a single piece of non-text content is used in different contexts that require different text alternatives.
An image used as a button
A magnifying glass icon is used to link to the search page of a Web site. A screen reader identifies the button as a link and speaks the text alternative, "Search."
Excerpts from the NBA Tape Recording Manual, Third Edition. Information on describing complex images to people who are blind.
1.1.3 For non-text content that is intended to create a specific sensory experience, text alternatives at least identify the non-text content with a descriptive label. (Level 1)
non-text content that causes a sensory experience that does not primarily convey important information or perform a function.
Programmatically determined text that is used in place of non-text content or text that is used in addition to non-text content and referred to from the programmatically determined text.
People who are not able to fully perceive content that is intended primarily to create a sensory experience can become confused about the purpose of this content if its name or short description is not provided. Although they may not be able to perceive and experience this content, giving its name (or a short description) will help these people understand what it is that they have encountered in the content.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.1.3.
Providing the descriptive name or the name the artist (or another) gave to the non-text content, using a technology-specific technique for providing short text alternatives listed below.
The following are common mistakes which are considered failures of this success criterion by the working group.
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
Providing an additional description of the non-text content using a technology-specific technique for long description listed below.
If non-text content does not have a label, a screen reader or braille display will not know how to identify it. Without text alternatives, people who are blind or deaf blind and using a screen reader or braille display won't know what they are encountering. Even if they cannot see a painting for example, being able to hear its name (or a short description) will help them understand what it is that they have encountered in the content.
A recording of a symphony.
The Mars Philharmonic Orchestra's "Upcoming performances" page has a link to a 3 minute clip of the orchestra's rendition of Beethoven's 5th Symphony. The purpose is to encourage readers to buy tickets to a live performance. The link to the audio clip says, "Beethoven's 5th Symphony performed by the Mars Philharmonic Orchestra." On the same page is information about Beethoven and the 5th Symphony.
Both pages satisfy this success criterion.
1.1.4 Non-text content that is not functional, is not used to convey information, and does not create a specific sensory experience is implemented such that it can be ignored by assistive technology. (Level 1)
Content that is not represented by a Unicode character or sequence of Unicode characters when rendered in a user agent according to the formal specification of the content type. This includes ASCII Art, which is a pattern of characters.
Performs or is able to perform one or more actions in response to user input.
non-text content that causes a sensory experience that does not primarily convey important information or perform a function.
Non-text content that does not have a specific purpose for users of the content (convey information, perform a function or create a specific sensory experience) should not be described because that would slow down certain users who are accessing the content in text mode. However, if it had no text alternative, then the user is left wondering what the content was. The purpose of this success criterion is to cause such content to be identifiable by assistive technologies as content that should just be skipped over.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.1.4.
Marking the non-text content using one of the technology-specific techniques listed below.
Editorial Note: Not all mechanisms for including non-text content have a convention similar to empty alt for img elements (object and embed are two examples). Are there additional strategies/techniques for addressing this criterion that should be included here to address this?
The following are common mistakes which are considered failures of this success criterion by the working group.
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
Users of screen readers or braille output devices are not slowed down by data that have no purpose for them.
A pair of images used to create a visual effect.
Two images are used to create curved edges on a "tab" interface. The images do not provide information, functionality, or a sensory experience and are marked such that they can be ignored by an assistive technology (e.g. alt="").
'background-image' - from the CSS 2.1 Candidate Recommendation - how to use CSS to specify background images.
1.1.5 For live audio-only or video-only content, text alternatives at least identify the purpose of the content with a descriptive label. (Level 1)
Note: Refer to Provide synchronized alternatives for multimedia.: for guidance on content that combines live audio and video.
A time-based live presentation that only contains only audio (no video and no interaction).
A time-based live presentation that only contains only video (no audio and no interaction).
Programmatically determined text that is used in place of non-text content or text that is used in addition to non-text content and referred to from the programmatically determined text.
The intent of this success criterion is to ensure that people who are unable to perceive live audio or live video are able to at least know what the content is about.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.1.5.
Providing a descriptive label that describes the purpose of live audio-only and live video-only content, using a technology-specific technique listed below.
The following are common mistakes which are considered failures of this success criterion by the working group.
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
People with visual impairments and/or cognitive difficulties can have the description read to them with assistive technology to help determine the purpose of the content.
People with hearing impairments can read the description to help determine the purpose of the content.
People who are deaf and blind can determine the purpose of the content in braille.
A streaming audio speech.
The link to a streaming live audio speech is labeled, "Finnie Jones' Speech to the Congregation".
A live video (no sound).
The link to a live video (no sound) of a professor answering questions about a new theorem is labeled, "Professor Vanderhelm explains and answers questions on Plinthal's Theorem - Live".
A live radio broadcast.
A radio station broadcasts over the internet. The station's Web site describes the genre of music played, a schedule of the shows, and the "current song" is updated each time the DJ starts a new track.
An online class.
The link to a streaming presentation of a chemistry class goes beyond minimum by not only describing the topic but providing links to lecture notes to be used and related readings.
1.1.6 For prerecorded multimedia content, a combined document containing both captions and transcripts of audio descriptions of video is available. (Level 3)
Synchronized transcripts of dialogue and important sound effects. Captions provide access to multimedia for people who are deaf or hard of hearing.
Audio narration that is added to the soundtrack to explain important details that cannot be understood from the main soundtrack alone. During pauses in dialog, audio descriptions of video provide information about actions, characters, scene changes and on-screen text to people who are blind or visually impaired.
This success criterion is designed to make audio visual material available to individuals whose vision is too poor to reliably read captions and whose hearing is too poor to reliably hear dialogue and audio descriptions. This is done by providing a single text document which consists of a combination of the captions (see SC 1.2.1) and a text transcript of the audio descriptions (see SC 1.2.2).
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.1.6.
Providing a collated script of captions and audio descriptions AND one of the following:
placing a link to the script immediately next to the non-text content;
linking to a collated script, using a technology-specific technique listed below.
The following are common mistakes which are considered failures of this success criterion by the working group.
People who cannot see well or at all and who also cannot hear well or at all can get access to information in audio-visual presentations.
A text description of a movie.
An author takes a recording of a movie with descriptions and transcribes both the text and the audio description. She then watches the move picking up any additional information that is in the captions such as sounds or speakers and adds it to the transcription. The result is posted on the web with a link to it immediately next to the link to the movie.
1.2.1 Captions are provided for prerecorded multimedia. (Level 1)
Editorial Note: The working group is seeking comment on the following proposal:
Change 1.2.1 to " Provide captions OR provide a text transcript of all audio intermixed with a text description of what is happening visually."
so authors have an option of providing captions OR a text script. Then, at Level 2, require captions.
Synchronized transcripts of dialogue and important sound effects. Captions provide access to multimedia for people who are deaf or hard of hearing.
For the purposes of these guidelines, multimedia refers to combined audio and video presentations. It also includes audio-only and video-only presentations that include interaction.
The intent of this success criterion is to enable people who are deaf or hard of hearing to watch multimedia presentations. Captions provide the part of the content available via the audio track. Captions not only include dialog, but identify who is speaking and notate sound effects and other significant audio.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.2.1.
SMIL 1.0 Techniques
SMIL 2.0 Techniques
The following are common mistakes which are considered failures of this success criterion by the working group.
Caption does not meet the definition of a caption (i.e. it doesn't include both dialog and important sound effects).
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
Additional SMIL 1.0 Techniques (Advisory)
Providing captions for all languages for which there are audio tracks.
Additional SMIL 2.0 Techniques (Advisory)
Providing SMIL 2.0 captions for all languages for which there are audio tracks.
People who are deaf or have a hearing loss can access the auditory information in the multimedia content through captions.
A captioned tutorial
A video clip shows how to tie a knot. The captions read,
"(music)
USING ROPE TO TIE KNOTS WAS AN IMPORTANT SKILL
FOR THE LIKES OF SAILORS, SOLDIERS, AND WOODSMEN."
From Sample Transcript Formatting by Whit Anderson.
1.2.2 Audio descriptions of video are provided for prerecorded multimedia (Level 1)
Editorial Note: The working group is seeking comment on the following proposal:
Change 1.2.2 to " Provide audio descriptions OR provide a text transcript of all audio intermixed with a text description of what is happening visually."
so authors have an option of providing audio descriptions OR a text script. Then, at Level 2, require audio descriptions.
Audio narration that is added to the soundtrack to explain important details that cannot be understood from the main soundtrack alone. During pauses in dialog, audio descriptions of video provide information about actions, characters, scene changes and on-screen text to people who are blind or visually impaired.
For the purposes of these guidelines, multimedia refers to combined audio and video presentations. It also includes audio-only and video-only presentations that include interaction.
The intent of this success criterion is to provide people who are blind or vision impaired access to a multimedia presentation. The audio description augments the audio portion of the presentation with the information needed when the video portion is not available.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.2.2.
Using a technology-specific technique to create and incorporate or programmatically associate audio description for the multimedia content.
SMIL 1.0 Techniques
SMIL 2.0 Techniques
The following are common mistakes which are considered failures of this success criterion by the working group.
(None currently documented.)
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
(None currently documented.)
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 audio descriptions of visual information.
A movie with audio description.
Describer: A title, "Teaching Evolution Case Studies. Bonnie Chen." A teacher shows photographs of birds with long, thin beaks.
Bonnie Chen: "These photos were all taken at the Everglades."
Describer: The teacher hands each student two flat, thin wooden sticks.
Bonnie Chen: "Today you will pretend to be a species of wading bird that has a beak like this."
Describer: The teacher holds two of the sticks to her mouth making the shape of a beak.
Transcript of audio based on the first few minutes of, "Teaching Evolution Case Studies, Bonnie Chen" (copyright WGBH and Clear Blue Sky Productions, Inc.)
1.2.3 Real-time captions are provided for live multimedia. (Level 2)
Synchronized transcripts of dialogue and important sound effects. Captions provide access to multimedia for people who are deaf or hard of hearing.
For the purposes of these guidelines, multimedia refers to combined audio and video presentations. It also includes audio-only and video-only presentations that include interaction.
The intent of this success criterion is to enable people who are deaf or hard of hearing to watch real-time presentations. Captions provide the part of the content available via the audio track. Captions not only include dialog, but also identify who is speaking and notate sound effects and other significant audio.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.2.3.
Note: Captions may be generated using real-time text translation service (stenographic or someday speech-to-text with corrections).
The following are common mistakes which are considered failures of this success criterion by the working group.
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
People who are deaf or have a hearing loss can access the auditory information in the multimedia content through captions.
A webcast
A news organization provides a live, captioned webcast.
1.2.4 Sign language interpretation is provided for multimedia (Level 3)
providing the translation and meaning of spoken words into specific gestures, hand positions and hand movements.
For the purposes of these guidelines, multimedia refers to combined audio and video presentations. It also includes audio-only and video-only presentations that include interaction.
The intent of this success criterion is to enable people who are deaf or hard of hearing and who are fluent in the sign language to watch multimedia presentations. Many people find it easier to follow sign language than to read the text of captions, since the captions are often a second language to them.
Note: The sign language for each country is a separate language from the spoken language.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.2.4.
The following are common mistakes which are considered failures of this success criterion by the working group.
(None currently documented.)
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
There is a segment of the population that is able to communicate in sign language, but may have weak reading skills. These individuals may not be able to read and comprehend the captions and thus require a sign language interpretation to gain access to the multimedia content.
Some people who communicate using sign language and are proficient readers may have impaired vision which may make it difficult to read the captions on the screen. A sign language interpretation may be easier to view.
Example 1. A corporation is making an important announcement to all of its employees. The meeting will be held in the main headquarters and streamed to the web. A sign language interpreter is provided at the meeting location. The live video includes a full view of the sign language interpreter as well as the person presenting.
Example 2.The same announcement as Example 1 is also webcast to remote employees. Since there is only one display available for this, the sign language interpreter is shown in the corner of the display.
Example 3.A university is providing an on-line version of a particular lecture by creating a multimedia presentation of the professor delivering the lecture. The presentation includes video of the professor speaking and demonstrating a science experiment. A sign language interpretation of the lecture is created and presented on the web with the multimedia version.
National Institute on Deafness and other Communication Disorders: Information on American Sign Language.
1.2.5 Extended audio descriptions of video are provided for prerecorded multimedia. (Level 3)
audio descriptions that are added to an audio/visual presentation by pausing the video so that there is time to add addional description. This technique is only used when the sense of the video would be lost without the additional audio description.
For the purposes of these guidelines, multimedia refers to combined audio and video presentations. It also includes audio-only and video-only presentations that include interaction.
The intent of this success criterion is to provide people who are blind or vision impaired access to a multimedia presentation beyond that which can be provided by standard audio descriptions.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.2.5.
Creating an extended audio description for the multimedia content using a technology-specific technique listed below.
The following are common mistakes which are considered failures of this success criterion by the working group.
(None currently documented.)
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
People who are blind, people with low vision who cannot see the screen, as well as those with cognitive disabilities who have difficulty interpreting visually, often use audio descriptions of the visual information. However, if there is too much dialog - the audio descriptions are insufficient. Extended audio descriptions can provide the additional information they need to really understand the video.
(none documented at this time)
1.3.1 Perceivable structures within the content can be programmatically determined. (Level 1)
The way the parts of an authored unit are organized in relation to each other and;
The way a collection of authored units is organized in relation to a delivery unit and;
The way a collection of delivery units is organized
can be recognized by user agents, including assistive technologies, that support the technologies in the chosen baseline
The intent of this success criterion is to enable assistive technology to render Web content in an alternative presentation such as synthesized speech or using larger fonts or different colors while preserving the important structural relationships in the content.
Web content developers add structure to information in order to organize it in a way that makes it easier to understand. Sighted users perceive the structure through various visual cues — headings are often in a larger, bold font a separated from paragraphs by blank lines; list items are preceded by a bullet and perhaps indented; paragraphs are separated by a blank line; items that share a common characteristic are organized into tabular rows and columns; form fields may be positioned as groups that share text labels.
The purpose of this success criterion is to ensure that any structure that is perceivable to one set of users can be made to be perceivable to all.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.3.1.
The following are common mistakes which are considered failures of this success criterion by the working group.
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
(None currently documented.)
Providing the ability to programmatically determine structure allows Web content to be presented differently to meet the needs and constraints of people with visual, hearing, and cognitive disabilities. In order for the information to be presented differently, it is necessary for the assistive technology to be able to understand the type of information. For example, if tables of information are programmatically identified as tables, a screen reader can unambiguously determine the contents of each table cell. If tables are instead created simply by positioning content in vertical columns, screen readers will only be able to read each line of text. If the "visual cells" contain more than one line of information, the user will not be able to understand it because the lines of each cell will get intermixed with the corresponding lines in the other cells. The screen reader will read the first line of each cell, then the next line of each cell, and so on.
A form that uses color and an asterisk to indicated required fields
A form contains both required and optional fields. Instructions at the top of the form explain that required fields are labeled with red text and also with an asterisk. Both the red text and the asterisk are programmatically associated with the appropriate form fields so that assistive technology users can determine the required fields.
A bus schedule table where the headers for each cell can be programmatically determined
A bus schedule consists of a table with the bus stops listed vertically in the first column and the different buses listed horizontally across the first row. Each cell contains the time when the bus will be at that bus stop. The bus stop and bus cells are identified as headers for their corresponding row or column so that an assistive technology can programmatically determine which bus and which bus stop are associated with the time in each cell.
A form where the labels for the checkboxes can be programmatically determined
In a form, the labels for each checkbox can be programmatically determined by an assistive technology.
A text document
A simple text document is formatted with double blank lines before titles, asterisks for bullets and other standard formatting conventions so that its structure can be programmatically determined.
1.3.2 When information is conveyed by color, the color can be programmatically determined or the information is also conveyed through another means that does not depend on the user's ability to differentiate colors. (Level 1)
perception of the color attributes is essential to understanding a piece of content
can be recognized by user agents, including assistive technologies, that support the technologies in the chosen baseline
The intent of this success criterion is to ensure that all users can access information that is conveyed by color. If the information is conveyed through color in an image (or other non-text format), the color cannot be programmatically determined by assistive technology. In this case, providing the information conveyed with color through another means ensures that assistive technology users who cannot see the color can still perceive the information.
Color is an important asset in design of Web content, enhancing its aesthetic appeal, its usability, and its accessibility. However, some users have difficulty perceiving color. People with partial sight often experience limited color vision, and many older users do not see color well. In addition, people using text-only, limited-color or monochrome displays and browsers will be unable to access information that is presented only in color.
When color is essential to understanding content, making sure the color can be programmatically determined allows assistive technologies to inform the user about the color so they can access the information conveyed by the color. Alternately, the information conveyed by color could be made accessible by also conveying it in a non-color dependent way.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.3.2.
Using text and text formatting (e.g. Unicode text with color styling) AND Using the same colored text in the legend or instructions introducing the use of color.
Ensuring that color encoded information is also available in text (a description).
Including a character cue whenever color cues are used (e.g. asterisk next to red items).
Using color and pattern (for example, colors on bar/pie charts with lines or texture fills).
The following are common mistakes which are considered failures of this success criterion by the working group.
User with visual disabilities.
Users with partial sight often experience limited color vision.
Users who are blind (using a text-only reader) and need to determine information based on color.
Some older users may not be able to see color well.
Users who have color-blindness.
Users with hearing and visual disabilities.
Users who are blind-deaf using Braille (text) refreshable displays may be unable to access color-dependent information.
People using text-only, limited color or monochrome displays may be unable to access color-dependent information.
Users with a handheld device which renders information but with no color context.
People using text-only, limited color or monochrome browsers (user agents) may be unable to access color-dependent information.
A form that uses color and an asterisk to indicated required fields
A form contains both required and optional fields. Instructions at the top of the form explain that required fields are labeled with red text and also with an asterisk. Both the red text and the asterisk are programmatically associated with the appropriate form fields so that assistive technology users can determine the required fields.
An examination.
Students view an SVG image of a chemical compound and identify the chemical elements present based on the colors used in the diagram. The text alternatives associated with each element name the color of the element and indicate the element's position in the diagram. Students who cannot perceive color have the same information about the compound as their classmates. (This technique also satisfies Guideline 1.1 Level 1.)
1.3.3 Information that is conveyed by variations in presentation of text is also conveyed in text or the variations in presentation of text can be programmatically determined. (Level 2)
Presentation is the rendering of the content and structure in a form that can be perceived by the user.
can be recognized by user agents, including assistive technologies, that support the technologies in the chosen baseline
The intent of this success criterion is to make information conveyed by varying the presentation of text available even if the information is presented in an alternative modality or if the person cannot perceive the text variations.
On a visual medium, examples of variations in the presentational of text would include:
emphasizing some words by bolding, italicizing or underlining them;
indicating content headings by increased font size and bolding font;
emphasizing words or indicating that they have special status (such as a key term) by changing the font family used to present them;
emphasizing words by raising them above centerline in a line of text.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.3.3.
Using technology-specific standard techniques for marking emphasized or special text.
Providing the same information redundantly in the running text.
The following are common mistakes which are considered failures of this success criterion by the working group.
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
(None currently documented.)
Users of screen readers or refreshable braille displays may be unable to access information conveyed by the formatting of text.
People with decreased visual perception, including some older users, may not see text formatting well.
(none provided at this time)
1.3.4 Any information that is conveyed by color is visually evident when color is not available. (Level 2)
perception of the color attributes is essential to understanding a piece of content
The intent of this success criterion is to ensure that all users can access information that is conveyed by color.
This success criterion is similar to 1.3.2. However where 1.3.2 allows color information to be made accessible directly OR via assistive technology — this success criterion (1.3.4) is focused on people with color anomalies who do not use assistive technologies. Hence this success criterion is focused on seeing that information conveyed via color is available without color and without requiring the person to use any assistive technologies.
Color is an important asset in the design of Web content, enhancing its aesthetic appeal, its usability, and its accessibility. It is not the intent of this success criterion to discourage its use. However, some users have difficulty perceiving color. People with partial sight often experience limited color vision, and many older users do not see color well. In addition, people using text-only, limited-color or monochrome displays and browsers will be unable to access information that is presented only in color
Therefore, when color is essential to understanding content, it is important to make sure that the information conveyed by color is also conveyed in a non-color dependent way.
The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 1.3.4.
Instructions: Select the situation below that matches your content. Beneath it are the option(s) that are known and documented to be sufficient for that situation. For the technology-specific techniques, see the options for the technology you are using listed immediately below.
The following are common mistakes which are considered failures of this success criterion by the working group.
(None currently documented.)
Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.
Color is an important asset in Web design, enhancing usability and aesthetic appeal. However, some users have difficulty perceiving color. People with partial sight often experience limited color vision, and many older users do not see color well. In addition, people using text-only and monochrome displays will be unable to access information that is presented only in color.
A form that uses color and an asterisk to indicated required fields
A form contains both required and optional fields. Instructions at the top of the form explain that required fields are labeled with red text and also with an asterisk. Both the red text and the asterisk are programmatically associated with the appropriate form fields so that assistive technology users can determine the required fields.
An examination.
Students view an SVG image of a chemical compound and identify the chemical elements present based on the colors used in the diagram. The text alternatives associated with each element name the color of the element and indicate the element's position in the diagram. Students who cannot