Guideline 1.1
Text Alternatives: Provide text alternatives for any non-text content
so that it can be changed into other forms people need, such as large
print, braille, speech, symbols or simpler language.
1.1.1
Non-text Content: All non-text content that is presented to the user
has a text alternative that serves the equivalent purpose, except for
the situations listed below. (Level A)
Guideline 1.2 Time-based Media: Provide alternatives for time-based media.
1.2.1
Audio-only and Video-only (Prerecorded): For prerecorded audio-only and
prerecorded video-only media, the following are true, except when the
audio or video is a media alternative for text and is clearly labeled
as such: (Level A)
1.2.2
Captions (Prerecorded): Captions are provided for all prerecorded audio
content in synchronized media, except when the media is a media
alternative for text and is clearly labeled as such. (Level A)
1.2.3
Audio Description or Media Alternative (Prerecorded): An alternative
for time-based media or audio description of the prerecorded video
content is provided for synchronized media, except when the media is a
media alternative for text and is clearly labeled as such. (Level A)
1.2.4 Captions (Live): Captions are provided for all live audio content in synchronized media. (Level AA)
1.2.5
Audio Description (Prerecorded): Audio description is provided for all
prerecorded video content in synchronized media. (Level AA)
1.2.6
Sign Language (Prerecorded): Sign language interpretation is provided
for all prerecorded audio content in synchronized media. (Level AAA)
1.2.7
Extended Audio Description (Prerecorded): Where pauses in foreground
audio are insufficient to allow audio descriptions to convey the sense
of the video, extended audio description is provided for all
prerecorded video content in synchronized media. (Level AAA)
1.2.8
Media Alternative (Prerecorded): An alternative for time-based media is
provided for all prerecorded synchronized media and for all prerecorded
video-only media. (Level AAA)
1.2.9
Audio-only (Live): An alternative for time-based media that presents
equivalent information for live audio-only content is provided. (Level
AAA)
Guideline 1.3 Adaptable:
Create content that can be presented in different ways (for example
simpler layout) without losing information or structure.
1.3.1
Info and Relationships: Information, structure, and relationships
conveyed through presentation can be programmatically determined or are
available in text. (Level A)
1.3.2
Meaningful Sequence: When the sequence in which content is presented
affects its meaning, a correct reading sequence can be programmatically
determined. (Level A)
1.3.3
Sensory Characteristics: Instructions provided for understanding and
operating content do not rely solely on sensory characteristics of
components such as shape, size, visual location, orientation, or sound.
(Level A)
Guideline 1.4 Distinguishable: Make it easier for users to see and hear content including separating foreground from background.
1.4.1
Use of Color: Color is not used as the only visual means of conveying
information, indicating an action, prompting a response, or
distinguishing a visual element. (Level A)
1.4.2
Audio Control: If any audio on a Web page plays automatically for more
than 3 seconds, either a mechanism is available to pause or stop the
audio, or a mechanism is available to control audio volume
independently from the overall system volume level. (Level A)
1.4.3
Contrast (Minimum): The visual presentation of text and images of text
has a contrast ratio of at least 4.5:1, except for the following:
(Level AA)
Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1;
Incidental:
Text or images of text that are part of an inactive user interface
component, that are pure decoration, that are not visible to anyone, or
that are part of a picture that contains significant other visual
content, have no contrast requirement.
Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.
1.4.4
Resize text: Except for captions and images of text, text can be
resized without assistive technology up to 200 percent without loss of
content or functionality. (Level AA)
1.4.5
Images of Text: If the technologies being used can achieve the visual
presentation, text is used to convey information rather than images of
text except for the following: (Level AA)
Customizable: The image of text can be visually customized to the user's requirements;
Essential: A particular presentation of text is essential to the information being conveyed.
1.4.6
Contrast (Enhanced): The visual presentation of text and images of text
has a contrast ratio of at least 7:1, except for the following: (Level
AAA)
Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 4.5:1;
Incidental:
Text or images of text that are part of an inactive user interface
component, that are pure decoration, that are not visible to anyone, or
that are part of a picture that contains significant other visual
content, have no contrast requirement.
Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.
1.4.7
Low or No Background Audio: For prerecorded audio-only content that (1)
contains primarily speech in the foreground, (2) is not an audio
CAPTCHA or audio logo, and (3) is not vocalization intended to be
primarily musical expression such as singing or rapping, at least one
of the following is true: (Level AAA)
No Background: The audio does not contain background sounds.
Turn Off: The background sounds can be turned off.
20 dB:
The background sounds are at least 20 decibels lower than the
foreground speech content, with the exception of occasional sounds that
last for only one or two seconds.
1.4.8
Visual Presentation: For the visual presentation of blocks of text, a
mechanism is available to achieve the following: (Level AAA)
1. Foreground and background colors can be selected by the user.
2.Width is no more than 80 characters or glyphs (40 if CJK).
3. Text is not justified (aligned to both the left and the right margins).
4.Line
spacing (leading) is at least space-and-a-half within paragraphs, and
paragraph spacing is at least 1.5 times larger than the line spacing.
5.
Text can be resized without assistive technology up to 200 percent in a
way that does not require the user to scroll horizontally to read a
line of text on a full-screen window.
1.4.9
Images of Text (No Exception): Images of text are only used for pure
decoration or where a particular presentation of text is essential to
the information being conveyed. (Level AAA)
WCAG 2.0 Layers of Guidance
(from https://www.w3.org/TR/WCAG20/)
The individuals and organizations
that use WCAG vary widely and include Web designers and developers,
policy makers, purchasing agents, teachers, and students. In order to
meet the varying needs of this audience, several layers of guidance are
provided including overall principles, general guidelines, testable success criteria and a rich collection of sufficient techniques, advisory techniques, and documented common failures with examples, resource links and code.
Principles - At the top are four principles that provide the foundation for Web accessibility: perceivable, operable, understandable, and robust. See also Understanding the Four Principles of Accessibility.
Guidelines - Under the principles are
guidelines. The 12 guidelines provide the basic goals that authors
should work toward in order to make content more accessible to users
with different disabilities. The guidelines are not testable, but
provide the framework and overall objectives to help authors understand
the success criteria and better implement the techniques.
Success Criteria - For each guideline,
testable success criteria are provided to allow WCAG 2.0 to be used
where requirements and conformance testing are necessary such as in
design specification, purchasing, regulation, and contractual
agreements. In order to meet the needs of different groups and different
situations, three levels of conformance are defined: A (lowest), AA,
and AAA (highest). Additional information on WCAG levels can be found
in Understanding Levels of Conformance.
Sufficient and Advisory Techniques - For each of the guidelines and success criteria in the WCAG 2.0 document itself, the working group has also documented a wide variety of techniques. The techniques are informative and fall into two categories: those that are sufficient for meeting the success criteria and those that are advisory.
The advisory techniques go beyond what is required by the individual
success criteria and allow authors to better address the guidelines.
Some advisory techniques address accessibility barriers that are not
covered by the testable success criteria. Where common failures are
known, these are also documented. See also Sufficient and Advisory Techniques in Understanding WCAG 2.0.
All
of these layers of guidance (principles, guidelines, success criteria,
and sufficient and advisory techniques) work together to provide
guidance on how to make content more accessible. Authors are encouraged
to view and apply all layers that they are able to, including the
advisory techniques, in order to best address the needs of the widest
possible range of users.
Note that even content that conforms at
the highest level (AAA) will not be accessible to individuals with all
types, degrees, or combinations of disability, particularly in the
cognitive language and learning areas. Authors are encouraged to
consider the full range of techniques, including the advisory
techniques, as well as to seek relevant advice about current best
practice to ensure that Web content is accessible, as far as possible,
to this community. Metadata may assist users in finding content most suitable for their needs.