WD-WAI-PAGEAUTH-19981117
WAI Accessibility Guidelines: Page Authoring
W3C Working Draft - 17 November
1998
- This version:
- http://www.w3.org/WAI/GL/WD-WAI-PAGEAUTH-19981117
- Latest version:
- http://www.w3.org/WAI/GL/WD-WAI-PAGEAUTH
- Previous versions:
- http://www.w3.org/WAI/GL/WD-WAI-PAGEAUTH-19981023
- http://www.w3.org/WAI/GL/WD-WAI-PAGEAUTH-19981016
- Related documents:
- Table Version of the
Guidelines (not available at this time)
- Techniques
- Editors:
- Wendy Chisholm <chisholm@trace.wisc.edu>
Gregg Vanderheiden <gv@trace.wisc.edu>
Ian Jacobs <ij@w3.org>
Abstract
This document is a list of guidelines that page
authors should follow in order to make their pages more accessible for
people with disabilities as well as more useful to other users, new page
viewing technologies (mobile and voice), and electronic agents such as indexing
robots. Tools that generate documents in HTML (authoring tools, file conversion
packages, or other products) should make it easy for authors to produce
documents that follow these guidelines. This document is part of a series of
accessibility documents published by the Web
Accessibility Initiative.
Accessibility does not mean minimal page design, it means thoughtful page
design. These guidelines outline procedures for authors, particularly those
using multimedia content, to ensure that the content and functions provided by
those elements are available to all users. In general, authors should not be
discouraged from using multimedia, but rather should use it in a manner which
ensures that the material they publish is accessible to the widest possible
audience.
In this document references are made to some technologies that are not yet
widely supported or not supported consistently in current user agents
(browsers), such as new features introduced in HTML 4.0. Since this document is
"frozen" we can not list which features are supported as of
"today." Therefore, the
WAI Page Authoring
Techniques document links to information about feature support of various
browsers.
Status of this document
This is a W3C Working Draft for review by W3C members and other interested
parties. It 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".
This is work in progress and does not imply endorsement by, or the consensus
of, either W3C or members of the WAI GL Working Group.
This document has been produced as part of the
W3C WAI Activity, and is intended as a
draft of a Proposed Recommendation for authoring accessible Web pages. The goal
of the WAI-GL working group is discussed
in our charter.
Comments
Please send detailed comments on this document to
w3c-wai-gl@w3.org. Public comments about
the WAI author guidelines can also be sent to this mailing list.
- Rating and Classification
- A. Make sure pages transform gracefully
across users, techniques, and situations
- A.1. Provide alternative text for all
images, applets, and image maps
- A.2. Provide descriptions for important graphics,
scripts, or applets if they are not fully described through alternative text or
in the document's content.
- A.3. Provide textual equivalents (captions) for all
audio information
- A.4. Provide verbal descriptions of moving
visual information in both auditory and text form
- A.5. Ensure that text and graphics are perceivable and
understandable when viewed without color
- A.6. Indicate structure with structural
elements, and control presentation with presentation elements and style
sheets
- A.7. Provide supplemental information
needed to pronounce or interpret abbreviated or foreign text.
- A.8. Ensure that tables have necessary markup to
be properly restructured or presented by accessible browsers and other user
agents
- A.9. Ensure that pages using newer
technologies will transform gracefully into an accessible form if the
technology is not supported or is turned off.
- A.10. Ensure that moving, blinking, scrolling, or
auto-updating objects or pages may be paused or frozen
- A.11. Elements that contain their own user
interface should have accessibility built-in
- A.12. Use features that enable
activation of page elements via input devices other than a pointing device
(e.g., via keyboard, voice, etc.).
- A.13. Use interim accessibility
solutions so that assistive technologies and older browsers will operate
correctly.
- A.14. Wherever possible use a W3C technology in
accordance with guidelines on its proper use. Where this is either not
possible, or results in material that does not transform gracefully you must
provide an alternative version of the content that is accessible.
- B. Maximize usability by providing
context and orientation information and simplifying presentations of
information.
- B.1 Provide context and orientation
information for complex pages or elements.
- B.2. Provide mechanisms that facilitate
navigation within your site.
- B.3 Use language and formats that
facilitate comprehension of information.
- Appendix A: Testing
- Appendix B: Definitions
- Appendix C: Index of guidelines by
priority
- Appendix D: Index of techniques by
priority
- [PRIORITY 1]
- This guideline must be followed by an author, or one or
more groups of users will find it impossible to access information in the
document. Implementing this guideline is a basic requirement for some groups to
be able to use Web documents.
- [PRIORITY 2]
- This guideline should be followed by an author, or one
or more groups of users will find it difficult to access information in the
document. Implementing this guideline will significantly improve access to Web
documents.
- [PRIORITY 3]
- This guideline may be followed by an author to make it
easier for one or more groups of users to access information in the document.
Implementing this guideline will improve access to Web documents.
Each guideline and each technique has a priority listed.
For the guidelines, the priority refers to the importance of addressing the
issue identified by the guideline. For techniques, the priority refers to which
technique best improves accessibility with respect to this guideline. For
example, a Priority 1 guideline may have a Priority 1 technique, which
must be done to provide accessibility, and a Priority 3
technique, which may also be done to help address the issue.
A. Transform Gracefully
Make sure pages transform gracefully across users, technologies, and
situations
To "transform gracefully" means that a page remains usable despite
user, technological, or situational constraints. User constraints require that
the information is presented so that they are able to perceive or interact with
it due to a physical or sensory limitaiton on their part. However, this
limitation might be caused by a situation. The user who is blind has the same
limitations as someone whose eyes are busy while they drive a car.
Technological constraints are defined by the device a person is using to access
a document. A small screen on a PDA creates a similar usability contraint to a
person with low-vision who has magnified their screen such that they are
looking at the information as if through a very small screen.
Since HTML, XML, and other W3C technologies are designed with the
flexibility to create documents that may be formatted in various ways on a
variety of platforms, by virtue they support accessible design. Non-accessible
pages are a result of giving up this flexibility. Creating pages that transform
gracefully is not more costly, but requires a different design approach that
also makes pages compatible with emerging mobile technologies. The following
section A guidelines address the issue of creating pages that transform
gracefully. They all stem from the following general guideline:
Always separate the content on your site (what you
say), and the way you choose to structure that content (how you organize it),
from the way the content and structure are presented (how you want people to
"see" it or perceive it). (If the content is sensory
specific, such as audio or video, make it available in a form that allows
presentation in other senses.)
Documents that transform gracefully are:
- Able to be perceived entirely visually and entirely through
auditory means. This does not mean creating an entire auditory version
of your site. Screen readers will be able to speak all information on
a page as long as it is available in text.
- Operable on various types of hardware including devices without
mice, with small, low resolution, or black and white screens, with only voice
or text output, without screens, etc. Due to the inherent flexibility
of the design of W3C technologies your pages will be cross platform if you
follow the basic principles outlined in this document.
Guidelines A.1 - A.12 address these issues.
A.1. Provide
alternative text for all images, applets, and image maps.
[Priority 1]
This includes images used as submit buttons, bullets in lists, and all of
the links within an image map as well as invisible images used to layout a
page. Alternative
text does not describe the visual appearance of an image, applet, or image
map. Rather, it is used to represent the function that the image, applet, or
image map performs whether it be decorative, informative, or for purposes of
layout. If alternative text is not provided, users who are
blind, have low vision, or any user
who cannot or has chosen not to view graphics will not know the
purpose of the visual components on the page. Since "bare"
ASCII art (characters that form images) does not allow
alt-text, it must be marked up specially for this purpose.
Techniques:
- Provide alternative text for all
images (e.g., in HTML, via the "alt" attribute of the IMG
element, or via "title" or within the content of OBJECT).
[Priority 1] Note. This includes images used as image
maps, spacers,
bullets in lists,
and links.
- Provide alternative text for
all applets and other programatic objects(e.g., in HTML, via the
"alt" attribute or within the content of APPLET, or via the
"title" attribute or within the content of OBJECT). [Priority 1]
(see also A.11)
- For all image map links
- Provide alternative text for
graphical buttons (e.g., via the "alt" attribute for the HTML
INPUT type="image" element) [Priority 1]
- Do not use an image map to create a set of
buttons in a form. Instead,
use separate buttons
or images (accompanied by alternative text).
[Priority 2]
- Replace ASCII art
with an image and alternative text. [Priority 1 or 2 depending on the
importance of the information (e.g., an important
chart)] Note. If the description of (important) ASCII art is
long, provide a description in addition to alternative text (see A.2).
A.2. Provide
descriptions for important graphics, scripts, or applets if they are
not fully described through alternative text or in the document's content.
[Priority 1]
Otherwise, important information presented
graphically (charts, billboards, diagrams) will not be perceivable to people
with blindness, some people with low vision,
and users who have chosen not to view graphics, scripts, or
applets or whose browser does not support scripts or
applets.
Techniques:
- Provide
a long description of all graphics that convey
important information (e.g., in HTML, via
"longdesc" on IMG, with a d-link (or an invisible d-link), or as
content of OBJECT). [Priority 1]
A.3. Provide textual
equivalents (captions) for all audio information [Priority 1]
If the audio is associated with a visual presentation (movie or animation),
synchronize the
textual
equivalents with the visual presentation. Otherwise, users who are
deaf, or hard of hearing, or any user
who cannot or has chosen not to hear sound cannot perceive the
information presented through speech, sound effects, music, etc.
Techniques:
- For
stand-alone audio
files provide a textual transcript of all words spoken or sung as well as
all significant sounds. [Priority 1]
- For
audio associated with
video, provide a textual transcript (of dialog and sounds) synchronized
with the video (e.g., captions). [Priority 1]
- Where sounds are played automatically,
provide visual
notification and transcripts. [Priority 1 or 2 depending on the
importance of the sound]
A.4. Provide
verbal descriptions of moving visual information in both auditory and text
form (for movies, animations, etc.). [Priority 1]
If the visual presentation is associated with an auditory presentation
(e.g., for a movie), synchronize the audio version of the descriptions
with the existing auditory presentation and collate the text version of the descriptions with the
text transcript
(captions) of the primary audio track. Otherwise, if actions, body
language, or other visual cues present information that is not expressed
through auditory means as well (through dialogue, sound effects, etc.),
users who cannot see (or look at) the page will not be able to
perceive it. The collated text version allows access to the information by
devices that do not play movies and by people who are
deaf-blind.
Techniques:
- For short animations such as animated
"gifs" images,
provide alternative
text (see A.1)and a long description (see A.2) if needed. [Priority 1]
- For movies, provide
auditory
descriptions that are synchronized with the original audio.
[Priority 1]
- Provide a
text version of the
auditory description that is collated with the text transcript (captions)
of the primary audio track. [Priority 2]
A.5. Ensure that text and
graphics are perceivable and understandable when viewed without color.
[Priority 1]
Otherwise, if color is used to convey information, users who cannot
differentiate between certain colors (and users with devices
that have non-color or non-visual displays) will not receive the
information.
When foreground and background colors are too close to the same hue, they may
not provide sufficient contrast when viewed using monochrome
displays or by people with different types of color
deficiencies.
Techniques:
- Don't use color to
convey information unless the information is also clear from the markup
and/or text. [Priority 1]
- Use foreground and background
color combinations
that provide sufficient contrast when viewed by someone with color deficits
or when viewed on a black and white screen. [Priority 1]
A.6.
Indicate structure with structural elements, and control presentation
with presentation elements and style sheets. [Priority 2]
When structural elements
and attributes are used to create presentation effects, user agents
that allow users to navigate through the structure will be unable to
do so properly. Such practices also make it difficult to render the page on
other media and devices. For instance, in HTML, don't use H1 to create large,
bold face text unless that text is actually a top-level heading.
Techniques:
- Nest headings properly
(e.g., in HTML, H1 - H6). [Priority 2]
- Encode list structure and
list items properly e.g., in HTML, UL, OL, DL, LI). [Priority 2]
- Mark
up quotations (e.g., with the Q and BLOCKQUOTE elements in HTML). Do not
use quotation markup for formatting effects such as indentation. [Priority 2]
- Use style sheets to
control layout and presentation wherever possible as soon as a majority of
browsers in use support them well (see A.9).
Until then, simple tables (to control layout) and
bitmap text with
alt-text (for special text effects) may be used, with alternative pages
used as necessary to ensure that the information on the page is accessible (see A.14). [Priority 2]
- Use
relative sizing and
positioning (e.g., percent) rather than absolute (e.g., pixels or point).
[Priority 2]
A.7.
Provide supplemental information needed to pronounce or interpret
abbreviated or foreign text. [Priority 2]
Unless changes between multiple languages on the same page are identified,
and expansions for abbreviations and acronyms are provided, they may be
indecipherable when spoken or brailled. This
also means that the predominant language on the page must be identified.
Supplemental information also helps search engines find key words and identify
documents in a desired language.
Techniques:
- Clearly identify changes in the language of text
(e.g., the HTML "lang" attribute) [Priority 2]
- Specify the expansion of
abbreviations and acronyms (e.g., with the "title" attribute of
the HTML ABBR or ACRONYM elements). [Priority 2]
Many user agents restructure tables to present them. Without appropriate
markup, the tables will not make sense when restructured. Tables also present
special problems to users of screen
readers.
These guidelines benefit users that are accessing the table through
auditory means (e.g., an Automobile PC which operates by speech input and
output) or viewing only a portion of the page at a time (e.g.,
users with blindness or low vision using speech or a braille display, or other users of devices with
small displays, etc.).
Techniques:
- Provide
summaries for
tables (e.g., via the "summary" attribute on HTML TABLE
elements). [Priority 3]
- Identify headers for rows
and columns (e.g., the HTML TD and TH elements). [Priority 2]
- Where tables have
structural divisions
beyond those implicit in the rows and columns, use markup to identify those
divisions (e.g., in HTML, THEAD, TFOOT, TBODY, COLGROUP, the "axis"
and "scope" attributes, etc.). [Priority 2]
- Provide
abbreviations for
header labels (e.g., in HTML, the "abbr" attribute on TH).
[Priority 3]
- If a table is used for layout,
do not use any
structural markup for the purpose of visual formatting. For example, in
HTML do not use the table header (TH) element to cause the contents of a cell
to be displayed centered and in bold. Other attributes of a table, such as a
caption describing the layout purpose and content of columns is valuable,
particularly if some cells become navbars, frames, images, imagemaps, or lists
of links.
A.9. Ensure that
pages using newer technologies will transform gracefully into an accessible
form if the technology is not supported or is turned off.
[Priority 1]
The everchanging landscape of technologies available on the internet is
influenced by W3C Recommendations (such as HTML) and proprietary formats (such
as ShockWave, and PDF). However, with each new release of Recommendations,
browsers, or plug-ins, new features are added that may not be completely
backwards compatible. For example, HTML 4.0
added the ability to attach style sheets to a page and to embed scripts and
applets into a page. Older browsers ignore new features and
some users configure their browser not to make use of new
features. These users often see nothing more than a blank page or an
unusable page when new features do not transform gracefully.
Techniques:
- Frames:
- Provide
a fallback page for
pages that contain frames (e.g., by using NOFRAME in HTML).
[Priority 1]
- Ensure that the source of
each frame is a markup file, such as HTML. [Priority 1]
- For scripts that present critical information or
functions, provide an
alternative, equivalent presentation or mechanism (e.g., by using NOSCRIPT
in HTML). [Priority 1]
- For pages that use style sheets, ensure
that the contents of each page are
ordered and
structured so that they may read in the intended order even when the style
sheet is not used. [Priority 1]
- Applets:
- At a minimum:
- If possible, provide
an alternative
function or presentation in a format other than an applet. For example, a
canned "mpeg" movie of a physics simulation (written in Java) or a
single frame of the animation saved as a "gif" image.
[Priority 2]
See also A.14.2 - alternative pages.
A.10. Ensure that moving,
blinking, scrolling, or auto-updating objects or pages may be paused or
frozen. [Priority 1]
This is particularly important for objects that contain text and
does not apply to instant
redirection. Some people with cognitive
limitations or visual disabilities are unable to read
moving text quickly enough or at all. Movement can also cause such a
distraction that the rest of the page becomes unreadable for people with
cognitive disabilities. Screen
readers are unable to read moving text. People with
physical disabilities might not be able to move quickly or
accurately enough to interact with moving objects. People with
photosensitive epilepsy can have seizures triggered by flickering or
flashing in the 4 to 59 flashes per second (Hertz) range with a peak
sensitivity at 20 flashes per second as well as quick changes from dark to
light (like strobe lights).
Techniques:
- Movement should be avoided when possible,
but if it must be used, provide a mechanism to allow users to
freeze motion or
updates in applets and scripts or use style sheets and scripting to create
movement. (see also A.11) [Priority 2]
- For auto-refreshing or timed response
pages, provide a second copy of the page where refresh
only happens after a
link has been selected (until user agents provide this ability themselves).
[Priority 1]
- Avoid any blinking or
updating of the screen that causes flicker. [Priority 1]
Note 1. The BLINK and MARQUEE elements, commonly used in
HTML pages, are not defined in any W3C HTML specification and should not be
used. See A.14
Note 2. See also A.4.1 which
discusses animated "gifs."
A.11. Elements that
contain their own user interface should have accessibility built in.
[Priority 2]
The accessibility of objects with their own interface is independent of the
accessibility of the user agent. Accessibility must therefore be built into the
objects or an alternative must be provided (see A.12.4).
Technique:
- Where possible
make programatic
elements, such as scripts and applets, directly accessible (see also A.9.4). [Priority 1 if information
or functionality is important, and not presented
elsewhere,otherwise Priority 2]
A.12. Use
features that enable activation of page elements via input devices other than a
pointing device (e.g., via keyboard, voice, etc.). [Priority 1]
Someone who is using the page without sight, with voice input, or
with a keyboard (or input device other than a pointing device, e.g., a
mouse or braille display) will have a difficult
time navigating a page if operation requires a pointing device. If a page is
usable via a keyboard, it is more likely that it should also be operable via
speech input, or a command line interface. Access to image maps is
impossible for these users if alternatives are not provided.
Techniques:
- For
image maps, provide
alternative text for links. [Priority 1] (see
also A.1)
- If possible, ensure that
all elements that
have their own interface are keyboard operable (see also A.12). [Priority 2]
- Create a
logical tab order
through links, form controls, and objects (e.g., in HTML, via the
"tabindex" attribute or through logical page design).
[Priority 3]
- Provide
keyboard
shortcutsto links, including those in client-side image maps, form
controls, and groups of form controls (e.g., in HTML, via the
"accesskey" attribute) . [Priority 3]
A.13. Use
interim accessibility solutions so that assistive technologies and older
browsers will operate correctly. [Priority 2]
Older browsers are unable to "Tab" to edit
boxes, text areas and lists of consecutive links, making it difficult to
impossible for users to access them. Users not operating in a graphical
environment are disoriented by being transferred to a new window
without warning.
Techniques:
Until most users are able to secure newer technologies that address these
issues:
- Include
default, place-holding
characters in edit boxes and text areas. [Priority 3]
- Include
non-link, printable
characters (surrounded by spaces) between links that occur consecutively.
[Priority 3]
- Do not use pop-up
windows, new windows, or change active window unless the user is aware that
this is happening. [Priority 2]
- For all form controls with labels, ensure that the label is either:
- Until user agents and
screen readers are able to handle text presented
side-by-side, all tables that lay out text in parallel, word-wrapped
columns require a
linear text alternative (on the current page or some other).
[Priority 2]
A.14. Wherever possible use a W3C
technology in accordance with guidelines on its proper use. Where this is
either not possible, or results in material that does not transform gracefully
you must provide an alternative version of the content that is accessible.
[Priority 1]
Many non-HTML technologies (e.g., PDF, Shockwave, and other non-W3C data
formats) used to encode information require either plug-ins or stand-alone
applications that often create pages that cannot be viewed or navigated using
standard Web access tools. Also, W3C technologies may be used in ways that do
not transform gracefully (e.g., because the visual components are too complex,
or because assistive technologies or user agents (browsers) are lacking a
specific feature). By avoiding non-standard features (elements,
attributes, properties, etc. only supported by a specific browser type) and
ensuring that all technologies transform gracefully, your pages will be
accessible to more people using a wider variety of hardware and software.
Note. Not all PDF pages are accessible or readable after
being run through a PDF translator. Individually test each page for readability
after the translation process. If a page does not automatically translate,
revise the page until its PDF representation converts appropriately through the
publicly-available converter(s) or prepare and post an HTML or plain text
equivalent.
- If W3C technologies are used:
- Use the latest W3C specifications whenever
possible. [Priority 2]
- Avoid deprecated
elements whenever possible. [Priority 2]
- If, after all of your best efforts, you
can not avoid using a non-W3C technology or any W3C technology in an accessible
way then you MUST provide a link to an alternative page that:
- uses W3C technologies,
- is accessible,
- has equivalent information,
- is updated as often as the inaccessible (original) page
[Priority 1]
Note. Alternative pages should be used sparingly
since authors tend to neglect updating the alternative page as often as the
original page. An out-of-date page may be as frustrating as one that is
inaccessible since, in both cases, the information presented on the original
page is not available. Automatically generating alternative pages can make it
easier to keep up with updates. However, authors must be careful to ensure that
generated pages always make sense and that users be able to navigate a site by
following links on primary pages, alternative pages, or both.. Before resorting
to an alternative page you may want to reconsider the design of the original
page. A page that is too elaborate may deter a larger audience than you might
expect.
Guidelines and
methods for creating alternative pages
- When linking to resources that are not W3C technologies, indicate what type of
resource you are linking to. For example, to link to a PDF file from an
HTML document, set the "type" attribute to
"application/pdf" on the A element. [Priority 3]
B. Orientation, Navigation, and
Comprehension
Maximize usability by providing context and orientation information and
simplifying presentations of information.
To provide context and orientation information means that additional
information is provided to help users gain an understanding of the "big
picture" presented by a page, table, frame, or form. Oftentimes users are
limited to viewing only a portion of a page, either because they are accessing
the page one word at a time (speech synthesis or braille display), or one section at a time (small
display, or a magnified display).
B.1 Provide context and
orientation information for complex pages or elements. [Priority 1]
Complex relationships between elements on a page may also be difficult for
people with cognitive disabilities to interpret. Grouping and
providing contextual information about the relationships between elements can
be useful for all users
Techniques:
- Name each frame so that users can keep track of frames
by name (e.g., via the "title" attribute on HTML FRAME elements).
[Priority 1]
-
Describe the purpose of
frames and how they relate to each other if it is not obvious by the name
of the frame. (e.g., in HTML, use "longdesc". Until
"longdesc" is widely supported, also use a d-link or invisible
d-link). [Priority 2]
- Group form
controls (e.g., in HTML use the FIELDSET and LEGEND elements).
[Priority 2 for radio buttons and checkboxes, Priority 3 for other
controls.]
- Associate labels to their
controls (e.g., in HTML use LABEL and its "for" attribute).
[Priority 2]
- Create a hierarchy of long
lists of choices (e.g., with the HTML OPTGROUP element). [Priority 2]
Through good design, increase the chance that a person can easily find what
they are looking for and can easily navigate throughout the site. A clear
navigation structure will not only benefit people with cognitive
disabilities, but everyone that visits your site.
To decrease the amount of sifting readers perform to find
important information, place distinguishing
information at the beginning of headings, paragraphs, lists, etc. This is
commonly referred to as "front-loading" and is especially helpful for
people accessing information serially.
- Wherever possible, make link phrases as terse as possible yet
as meaningful as
possible when read on their own or in succession. Avoid non-meaningful
phrases, such as "click here." [Priority 2]
- Use a clear, consistent
navigation structure. [Priority 3]
- Offer
navigation bars for easy
access to the navigation structure. [Priority 3]
- Offer a
site map.
[Priority 3]
- Provide
a
description of the general layout of the site, the access features used,
and how to use them. [Priority 3]
- Offer
different types of
searches for different skill levels and preferences. [Priority 3]
- Place
distinguishing
information at the beginning of headings, paragraphs, lists, etc.
[Priority 3]
- Facilitate off-line browsing by creating
a
single downloadable file for documents that exist as a series of separate
pages (e.g., by using the HTML LINK element, or creating a "zip"
archive). [Priority 3]
- Group related
links, such as links used to create a navigation bar, and attach a
meaningful title on the element creating the group (e.g., in HTML use
"title" on FRAME, DIV, SPAN, etc.. Use class="nav" on
elements creating navigation groups). [Priority 3]
- Provide a link at
the beginning of a group of related links to bypass the group.
[Priority 3]
B.3 Use language
and formats that facilitate comprehension of information. [Priority 2]
Consistent page layouts, common icons, and easy to understand language will
benefit everyone in general, but especially people with cognitive
disabilities, people whose native language is not the same as
yours, or people who have difficulty reading.
However, ensure that images have alternative text for people who are
blind, have low vision, or any user
who cannot or has chosen not to view graphics (see A.1 - Alternative text).
- Use the
simplest and most straightforward language that is possible for the content
of your site. [Priority 2]
- Use icons or
graphics (with alternative text) where they facilitate comprehension of the
page. [Priority 3]
- Create a
consistent style of presentation between pages. [Priority 3]
Validate your pages and assess the accessibility with automated
tools, manual tests, and other services.
It is important to test your site with various types of browsers, older
versions of current browsers, and services that emulate browsers. Testing your
site with a variety of browsers and other services will allow you to gain
firsthand experience of some of the issues people deal with. Adjustments to
your design based on the results of tests will increase the likelihood that
your site will be usable by a wide range of people and technologies.
- Use an
automated accessibility,
and browser validation tool.
- Use the W3C HTML Validation Service,
available at http://validator.w3.org/
- Use the W3C CSS Validation Service,
available at http://jigsaw.w3.org/css-validator/
- Use a text-only browser or
emulator
- Use multiple graphic
browsers, with:
- sounds and graphics loaded,
- graphics not loaded,
- sounds not loaded,
- no mouse,
- frames, scripts, style sheets, and applets not loaded
- It may also be helpful to test a site with
a self-voicing browser, a
screen reader, magnification software, a small display, etc..
- Use a spell
checker. A person reading a page with a speech synthesizer may not be able
to decipher the synthesizer's best guess for a word with a spelling errror.
- Applet
- A program inserted into a Web page.
- ASCII art
- ASCII art refers to text characters and symbols that are combined to
create an image. For example ";-)" is the
smiley emoticon and the following drawing represents a cow.
(__)
(oo)
/-------\/
/ | ||
* ||----||
^^ ^^
- Backwards compatible
- Something that has been designed to work with earlier versions of a
language, program, etc.
- Braille
- Braille uses six raised dots in different patterns to represent letters
and numbers to be read by people who are blind with their fingertips.
The word "Accessible" in braille.
- Braille display
- A braille display, commonly referred to as a "dynamic braille
display," raises or lowers dot patterns on command from an electronic
device, usually a computer. The result is a line of braille that can change
from moment to moment. Dynamic braille displays range in size from one cell
(six or eight dots) to an eighty cell line. Displays with twelve to twenty
cells per line are most common, due to cost.
- Collate
- Webster's dictionary defines collate as, "To gather and place in
order, as the sheets of a book for binding." When refering to transcripts,
the text version of the descriptions and the text transcript (captions) of the
primary audio track are combined into a single document to read like a script
of the movie. In other words, the two documents are not combined but flows as a
single document.
- Image
- A graphical presentation.
- Image map
- An image that has been divided into regions; clicking in a region causes
an action to occur.
- Important
- Something is important if understanding it in detail is necessary for the
overall understanding of a document.
- Instant redirection
- A page is loaded but immediately replaced by another due to meta
information in the transient document.
- Page authors
- Those who are creating Web pages.
- Screen magnifier
- A software program that magnifies a portion of the screen, so that it can
be more easily viewed. Used primarily by individuals with low
vision.
- Screen reader
- A software program that reads the contents of the screen aloud to a user.
Used primarily by individuals who are blind, screen readers can usually only
read text that is printed, not painted, to the screen.
Appendix C: Guidelines by Priority
- Priority 1
-
- A.1. Provide alternative text for images,
applets, and image maps
- A.2. Provide descriptions for important
graphics, scripts, or applets if they are not fully described through
alternative text or in the document's content.
- A.3. Provide textual equivalents for audio
information
- A.4. Provide verbal descriptions of
moving visual information in both auditory and text form
- A.5. Ensure that text and graphics are perceivable
and understandable when viewed without color
- A.8. Ensure that tables have necessary markup
to be properly restructured or presented by accessible browsers and other user
agents
- A.9. Ensure that pages using newer
technologies will transform gracefully into an accessible form if the
technology is not supported or is turned off.
- A.10. Ensure that moving, blinking, scrolling, or
auto-updating objects or pages may be paused or frozen
- A.12. Use features that enable
activation of page elements via input devices other than a pointing device
(e.g., via keyboard, voice, etc.).
- A.14. Wherever possible use a W3C technology in
accordance with guidelines on its proper use. Where this is either not
possible, or results in material that does not transform gracefully you must
provide an alternative version of the content that is accessible.
- B.1 Provide context and orientation
information for complex pages or elements.
- Priority 2
-
- A.6. Indicate structure with
structural elements, and control presentation with presentation elements and
style sheets
- A.7. Provide supplemental
information needed to pronounce or interpret abbreviated or foreign text.
- A.11. Elements that contain their own user
interface should have accessibility built-in
- A.13. Use interim accessibility
solutions so that assistive technologies and older browsers will operate
correctly.
- B.2. Provide mechanisms that
facilitate navigation within your site.
- B.3 Use language and formats that
facilitate comprehension of information.
Appendix D: Techniques by priority
Under construction.