WD-WAI-UA-BROWSER-0518
WAI Accessibility User Agent Guidelines:
Browser User Interface
W3C Working Draft 18-May-1998
- Editor:
- Jon Gunderson, University of
Illinios at Urbana/Champaign
-
- Please see the Acknowledgements section
of the Appendix for a full listing of contributors.
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 User Agent (UA)
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 how to improve browser
accessibility. The goal of the WAI-UA working
group is discussed in our charter.
A list of the current
working group members is available.
Abstract
This document is a list of browser features that browser developers
should follow in order to make their browser technology more accessible to
persons with disabilities. Following the list of guidelines is a checklist
that browser developers can use to identify and prioritize accessibility
features. This document is part of a series of accessibility documents
published by the Web Accessibility
Initiative.
Comments
Please send detailed comments on this document to
w3c-wai-ua@w3.org. Public comments
about the WAI author guidelines can also be sent to this mailing
list.
Each guideline is accompanied by a rating that describes its importance
and scenarios about how the :
- [Priority 1]
- Very important, otherwise it will be impossible for
one or more groups of
users to access this information on the page, or it will
significantly improve the access to WWW pages designed without
accessibility considerations.
- [Priority 2]
- Important, otherwise it will be difficult for
one or more groups of
users to access this information on the page, or it will improve
the access to WWW pages designed without accessibility considerations.
- [Priority 3]
- Makes access to information on the page easier, but not critical for
access.
- Scenarios
- Short descriptions of how the changes impacts persons with different
types of disabilities on common WWW tasks and how it compensates for WWW
pages that are not designed for accessibility.
- Implement Ideas
- Considerations, options and ideas that developers can use for
implementing a particular access feature.
- Test Pages
- Self explanitory test pages that can be used by browser developers to
determine if a browser complies with a specific guideline.
Table of Contents
- [Priority 1]
User can adjust the default font face
used by the browser. Persons with visual impairments and learning
disabilities can adjust the font to the style characteristics that is
best for them to view WWW pages.
- [Priority 1]
User can adjust the default font size
used by the browser. Persons with visual impairments and learning
disabilities can adjust the font to the size that is best for them to
view WWW pages.
- [Priority 1]
User can adjust the default
foreground and background colors used by the browser.
Persons with visual impairments and learning disabilities can adjust the
display colors to the colors that are best for them to view WWW pages.
- [Priority 1]
User can turn off background images
- [Priority 1]
User can adjust the highlight
foreground and background colors used by the browser.
Persons with visual impairments and learning disabilities can adjust the
display highlight colors used to indicate selections of text.
Highlighted text is often used by third party assistive technologies to
indicate what the user wants to read through speech output. Highlighted
text can also be used by screen readers to indicate the focus of what
the user is trying to read. Some screen readers are sensitive to the
highlight colors.
- [Priority 1]
Keyboard command to switch between default browser presentation and
current user preferences.
- [Priority 1]
Implement the important rule
to allow users to override author CSS specifications.
- [Priority 1]
Use available operating system colors as the default colors and use
available operating system flags for automatically setting the browser
in a high contrast display mode.
- [Priority 2]
Support Aural Cascading Style Sheets
for the auditory presentation of WWW documents.
- [Priority 2]
User can specify a Cascading Style
Sheet to be used in cascading order specified in CSS2
after the document style sheets have been loaded. The style sheet is an
external linked style sheet is applied to all documents viewed. Users
can define a style sheet to meet the needs of their particular
capabilites and preferences. Browsers should support auditory style
sheets for presenting information auditory, visually or both.
- [Priority 3]
User can specify an external file to
set default browser style. This is very useful in public
access computer environments where there are multiple user of one
computer. The user can quickly adjust the browser to their preferences.
- [Priority 1]
A user selectable option is available to turn off
font face information
specified in the page being rendered by the browser. The default font
face is used to render the page text. This feature maintains users with
visual impairments and learning disabilities font face preferences and
are not overridden by page font face specifications.
- [Priority 1]
User selectable option is available to turn off font
size information specified in the page being rendered by
the browser. The default font size is used to render the page text. This
feature maintains users with visual impairments and learning
disabilities font size preferences and are not overridden by page font
face specifications.
- [Priority 1]
User selectable option is available to turn off color
information specified in the page being rendered by the browser. The
default colors for text and highlight are used to render the page text.
This feature maintains users with visual impairments and learning
disabilities font size preferences and are not overridden by page font
face specifications.
- [Priority 1]
User selectable option is available to turn off linked, embedded and
inline specified cascading style
sheets (CSS) information. CSS font, size, color and
positioning information would be ignored in the rendering of the page.
The page would render using the default browser options or a user
specified style sheet.
- [Priority 1]
User selectable option is available to turn off the display of
images using the
IMG tag and display
descriptive text in place of the image. There are three potential
sources of descriptive text information: ALT attribute,
TITLE attribute and NAME attribute if the
image is part of a Anchor. The priority of presentation
is the ALT, TITLE and then NAME
text. If none of these sources is available the name of the file
should be used as the alternative description. The entire text should
be rendered no matter what the source of the text or the dimensions
specified for the original image.
Usage of ALT and TITLE:
ALT: Image description.
TITLE: Tool tip
- [Priority 1]
When user selectable option to display images is turned off,
OBJECT tags being
used to specify images should not render the image, but instead should
display descriptive text information about the image. The inner most
text of the OBJECTis considered the alternative text for
the OBJECT and in the absence of text the OBJECT
filename should be used. The descriptive text should be fully
rendered, even if the dimensions of the image are smaller than the
dimensions specified for the image in theOBJECT.
- [Priority 1]
Images using the IMG
tag which include the LONGDESC
attribute should display a D-Link to the LONGDESC URL when
the user selectable option for image presentation is off. The D-Link
would be presented as part of the text description (discussed earlier in
this section). Keyboard commands are required to locate and select the
presentation of LONGDESC attribute information. In
addition the LONGDESC URL could also be selected through
mouse commands for able-bodied users or persons with LD who prefer to
use a mouse.
- [Priority 1]
User selectable option is available to turn on audio descriptions of
videoes, movies and annimations for videos.
- [Priority 1]
User selectable option is available to turn on closed captioning of
video, images and annimations.
- [Priority 1]
User option to turn off the presentation of imbedded applicaitons in a
document. The OBJECT
and APPLET
(depreciated) tags can be used to imbed applications within a document.
Users with some disabilities cannot use the applications, but need to
know the existance, purpose or function of the application. When this
option is enabled the alternative text for the application will be
rendered. In the case of the OBJECT
tag this is the text in the inner most object structure. In the case of
the APPLET tag the
ALT text should be rendered.
If an OBJECT or APPLETcould not be
loaded a message should appear reporting the reason why the object
could not be loaded (i.e. missing object, server not ready...).
- [Priority 2]
User has has the option to view information from selected tags in the
currently loaded document. This provides a means for a user to quickly
identify tags of interest on a page without needing to scroll through
the entire page and in some cases not being able to identify tags of
interest due to the lack of tag information available on the screen or
through assistive technology. For example headers (H1-H6) would be a
common alternative view for some one to quickly view the major topics
within a document. A keyboard/menu command is needed to change between
the full and outline view of the document. Switching between the outline
and full view would maintian a synchronized view between the two views
of the document. The tags that are displayed in the outline view should
be selectable by the user and be primarily block level tags.
- [Priority 2]
Elements generated in the outline view become links to the
corresponding elements in the original document. The user could use the
browser to navigate the outline view links and then move directly to the
item in the orginal document by selecting the link.
- [Priority 2]
Text only view of page. All non-text information is surpressed.
Alternative text is used for images and objects. Similar to the current
version of UNIX LYNX.
- [Priority 2]
User option to unwrap table views. The first line would give the size
and name of a table. Each cell would have one line with the table cell
row and column coordinates, which would be followed by the contents of
the cell.
- [Priority 1]
Maintenance of document view and element focus (currently only links
and form controls for many browsers) as a user moves between documents.
- [Priority 1]
Element focus follows changes in page view. When the user changes the
view of a page the element focus moves to that view. So if the user
after changing the view uses keyboard commands to move or select the
focused element the view does not abruptly change to another portion of
the document with the focus.
- [Priority 1]
Eement focus follows changes in page view. When the user changes the
view of a page the element focus moves to that view. So if the user
after changing the view uses keyboard commands to move or select the
focused element the view does not abruptly change to another portion of
the document with the focus.
- [Priority 1]
When selecting a link in one frame that changes the document loaded in
another currently visible frame, the focus is required to go to the new
frame.
- [Priority 1]
Brief document summary information is displayed on page loading on
status. Summary information includes information on the size of the
document, the number of structural elements related to
- [Priority 2]
Brief document summary information is displayed on status line on user
command.
- [Priority 2]
Extended document summary information is displayed on user command.
- [Priority 1]
Element and DHTML event identification on status line on focus/mouse
over events.
- [Priority 2]
Document TITLE found in the HEAD section of
the document should appear on a title bar, if a title bar or other
similar convention exists in the operating system.
- [Priority 1]
Support the
:before
and :after pseudo-elements of CSS2
recommendation. Users using speech output can include identifiers in the
document to indicate the type of element being spoken.
- [Priority 2]
Support the
Dynamic
outlines: the 'outline' property of CSS2
recommendation. Support of this feature allows the user to have greater
control over how element focus is rendered visually.
- [Priority 1]
Keyboard commands to sequentially move focus between frames, links,
images with LONGDESC and controls on a page.
- [Priority 2 or 3]
Keyboard commands to navigate a hierachical representation of the
document. The focus of the hierachy would be defined using the oultine
property of CSS2 or in a representation compatible with third party
assistive technology. The outline can be expanded or contracted based on
keyboard and pointing commands from the user. The hierachical
representation would include block level structures.
- [Priority 2]
Keyboard commands to move focus directly to links and controls on a
page. This feature is designed to assist in moving a user directly to a
known link (usually by link name) and to allow a user to identify links
that contain a list of keywords the user is interested in.
- [Priority 2]
Keyboard commands to move focus directly to non-link and non-control
elements in a document.
- [Priority 1]
Keyboard commands to move focus between cells in a table. The ability
to highlight a cell with a pseudo focus using outlines feature of CSS2
specification is important for this feature to benefit users with
disabilities.
- [Priority 1]
Keyboard navigation commands to switch focus between frames. Using the
keyboard to move frames should maintain relative position and focus in
each of the frames. The user therefore cannot lose their place just by
toggling through the frames.
- [Priority 1]
Salient visual focus indication for users with low vision to identify
the element in the current view that has the focus. The focus indication
should be adjustable by the user, so they can customize it to meet their
own capabilities.
- [Priority 1]
Focus indication for third party assistive technology to identify the
element the user is currentlt viewing.
- [Priority 1]
Support CSS element focus indication.
- [Priority 1]
The ability to identify elements with dynamic HTML events through
markings on the visual display and indications to 3rd party assistive
technology.
- [Priority 1]
Keyboard commands to view a list of Dynamic HTML Events and the
associated elements and to select an event to execute from the list.
- [Priority 1]
Keyboard commands to view a history list of the documents the user has
transversed and select documents from the list.
- [Priority 1]
Display keyboard shortcut navigation commands in menus. If the user
interface of the operating system supports placing keyboard shortcut
keys in menu items,
- [Priority 2]
If menu options exist for element navigation that menus also be used to
display summary information for elements associated with that menu. For
example if a browser has a menu item labled "Headers" and has
the ability to provide navigation bewteen header elements. The display
of headers menu could be in the format of "nn Headers" is the
number of headers in the current document. The sub menu items would
include Next Header, Previous Header, List of All Headers, and a dynamic
list of the first 10 headers in the document.
- [Priority 1]
Description of accessibility features are available in on-line
documentation. The on-line documentation needs to inlcude information on
features that can be used to improve the usability of the browser by
persons with disabilities and provide a list of all keyboard commands.
The search index should include references to key words like "disability",
"handicapped", "accessibility" and "impairment".
- [Priority 1]
Description of accessibility is available in print documentation. If
print manuals are distributed with the browser, there should be
information about accessibility information in the print manuals. The
table of contents and the index should have entries that clearly
identify disability access features.
- [Priority 1]
Print and on-line information should be available in alternative
formats for people with print impairments. This includes large print,
audio tape and Braille.
Using standard rather than custom controls in the designing browser
applications increases the accessibility of the application. Third party
assistive technology developers are more likely able to access standard
controls than custom controls. If you must use custom controls review them
for accessibility or check for controls that support Active Accessibility
or the SUN Soft Accessibility API (see following sections).
When developing new applications for Windows 95/NT build into the
specifications and design active accessibility compatibility. This
provides 3rd party asssistive technology with important information for
accessibility about your program for persons using 3rd part assistive
technology. More information on active accessibility can be found at
Microsoft WWW
site on Active Accessibility.
When developing new applications using SUNSoft Java technology build
into the specifications and design the use of the Java Accessibility API.
This provides 3rd party asssistive technology with important information
for accessibility, so persons with disabilities can use assistive
technology to more efficiently access your programs. More information on
Java Accessibility API can be found at
Java
Accessibility Utilities.
- WAI Markup Guidelines Working Group Chair:
- Jon Gunderson, University
of Illinois at Urbana/Champaign
- Staff contacts:
- Judy Brewer and
Daniel Dardailler
-
- In addition we would like to thank the following people who have
contributed through review and comment.
- James Allen, Irene Au, Kitch Barnicle, Kevin Carey, Wendy Chilstrom,
Chetz Colwell, Neal Ewers, Geoff Freed, Larry Goldberg, Jon Gunderson,
Chris Hasser, Phill Jenkins, Leonard Kasday, George Kerscher, Josh
Krieger, Greg Lowney, Scott Luebking, William Loughborough, Charles
McCathieNevile, Masafumi Nakane, Charles Opperman, Mike Paciello, David
Pawson, Helen Petrie, David Poehlman, Michael Pieper, Jan Richards, Greg
Rosmaita, Liam Quinn, T.V. Raman, Robert Savellis, Constantine
Stephanidis, Jim Thatcher
, Jutta Treviranus, Steve Tyler, Gregg Vanderheiden, Jaap van
Lelieveld, Jon S. von Tetzchner, Ben Weiss, Evan Wies, Chris Wilson,
Hank Wittingen, Tom Wlodkowski
If you have contributed to the UA guidelines and your name
does not appear please contact the editor to add your name to the list.
HTML 4.0
Recommendations.
W3C WAI Page Author Guidelines