ADVANCED DRAFT COPY
Central Reference Document - Version 8
Unified Web Site Accessibility Guidelines
January 20, 1998
Compiled by:
Gregg C. Vanderheiden Ph.D.,
Wendy A. Chisholm, M.S.,
Trace R and D Center, University of Wisconsin - Madison
For the Web Accessibility Initiative Guidelines Working Group
(This is a final Trace Center Guidelines Document.
It is compiled in preparation for transfer of the Guidelines to
the Web Accessibility Initiative of the W3C.
This guideline reflects recent work of the WAI as well as previous
contributions of many other guidelines developers (listed
in the appendix)). Contributors include: Jim Bell, Jane
Berliss, Harvey Bingham, Judy Brewer, Kevin Carey, John Churchill, David
Clark, Dan Connolly, Daniel Dardailler, Judith Dixon, Martin Durst, Paul
Fontaine, Geoff Freed, Alfred S. Gilman, Larry Goldberg, Jon Gunderson,
Markku Hakkinen, Scott Isaacs, Scott Isensee, Jun Ishikawa, Steve Jacobs,
Phill Jenkins, Alan Karben, Hiroshi Kawamura, George Kerscher, Peter
Korn, Josh Krieger, Chuck Letourneau, Edmund MacKenty, Murray Maloney,
Aya Matsui, Gabriel Michel, Jim Miller, Masafumi NAKANE, Charles Oppermann,
Mike Paciello, David Pawson, Michael Pieper, Dave Ragget, T.V. Raman, Jan
Richards, Madeleine Rothberg, Jutta Treviranus, Steve Tyler, Jaap Van Lelieveld,
Jason White, Tom Wlodkowski, ATRC, CAST, InfoUse, NCR, WGBH, WINGS, YRIF,
and the WAI IG and GL Working groups
(If you have contributed and your name or organization is missing
from the above list, inform us via e-mail so that
we may correct our omission - and we apologize in advance.)
Prepared under funding from
the National Institute on Disability and Rehabilitation Research
(NIDRR),
Office of Special Education and Rehabilitation Services (OSERS),
US Department of Education
The US Postal Service's WINGS project and
the NCSA-PACI Universal Design / Disability Access Project.
(This is a living document. Comments and suggestions are solicited.)
Table of Contents
-
About version 8 of the
Unified Web Site Accessibility Guidelines
-
Introduction
-
Purpose of Version 8
-
Format of Version 8
-
Simplifying the Guidelines
-
Input Requested
-
Introduction to web site
accessibility
-
[Place holder for "On SGML and HTML "]
-
Definitions and Conventions
-
Definitions
-
Types and encoding of recommendations
-
[Place holder for "HTML Document Representation - Character sets, character
encodings, and entities"]
-
[Place holder for "Basic HTML data types - Character data, colors, and
lengths"]
-
The global structure of an HTML document
- The HEAD and BODY of a document
-
Page Titles
-
Metadata
-
Language information and text direction
- International considerations for text
-
Text - Paragraphs, Lines, and Phrases
-
Text formatting
-
Acronyms
-
Punctuation, symbols and ASCII art
-
Text that changes or moves
-
Lists and Outlining - Unordered,
Ordered, and Definition Lists
-
Helping users navigate lists effectively
-
Tables
-
Comprehension and navigation of table elements
-
Links - Hypertext and Media-Independent
Links
-
Links read out of context
-
Identifying links within a sentence
-
Several links read as one
-
Methods for linking to alternate pages
-
Use of graphics decreases cognitive load
and increases target area.
-
Page abstracts
-
Keyboard shortcuts for links
-
Objects, Images, Audio, and Applets
-
Introduction to the issues
-
General recommendations
-
Images and image maps
-
Applets
-
Audio and video
-
Style Sheets - Controlling
the presentation of an HTML document
-
Style sheets solve several issues, but only if users
can override
-
Alignment, font styles, and horizontal rules
-
Providing additional cues with horizontal
rules
-
Frames - Multi-view presentation
of documents
-
Misinterpretation by screen readers and
small screen users
-
Forms - User-input Forms: Text
Fields, Buttons, Menus, and more
-
Navigation and manipulation
-
Graphical buttons
-
Scripts - Animated Documents
and Smart Forms
-
Introduction to the issues
-
Action occurring away from user
focus
-
Actions executed during load of page
-
Automatic update of page ("push")
-
Summary of issues
-
[Place holder for "SGML reference information for HTML - Formal definition
of HTML and validation"]
-
[Place holder for "SGML Declaration of HTML 4.0"]
-
[Place holder for "Document Type Definition"]
-
[Place holder for "Transitional Document Type Definition"]
-
[Place holder for "Frameset Document Type Definition"]
-
[Place holder for "Character entity references in HTML 4.0"]
-
Good Web Site Design Practices
-
Appendices
-
Design Notes
-
Alt-text
-
Alternate pages
-
References
1. About Version 8 of the
Unified Web Site Accessibility Guidelines
1.1 Introduction
The 8 series of website accessibility guidelines is the final
set of unified guidelines prepared by the Trace Center. The Web Access
Initiative (WAI) of the World-Wide-Web Consortium (W3C) has been launched,
and the development of HTML guidelines is being transferred to that body.
The Trace Center will be continuing to work with and as a part of the WAI.
As a result, the Trace Center will no longer be developing or maintaining
this Unified Website Accessibility Guideline series. Readers are referred
to the W3C site (http://www.w3.org/wai) for the latest version of the guidelines.
1.2 Purpose of Version 8
The primary purpose for compiling Version 8 is to bring together
all of the information, notes, and ideas that the Trace Center has been
able to locate (see appendix for listing of guidelines we were able to
locate). This version also takes into account decisions and directions
that were taken at the August 1997 WAI working group meeting, as well as
recent discussions by the working groups on-line (although at the present
time, some of those discussions have not reached conclusion).
1.3 Format of Version 8
Version 8 has been completely restructured from previous versions.
Part of this was to reflect decisions or directions in which the WAI decided
that it would like to take the guidelines at the August meeting. The greatest
restructuring, however, has been done so that these web guidelines would
directly follow the structure and numbering of topics in the new HTML 4.0
specification. In fact, in order to maintain the numbering, there are several
sections in this document that have almost nothing in them, or are just
place holders to keep the numbering aligned between these
guidelines and the HTML 4.0 specification.
This document is actually one of a series of documents that make up
the Unified Website Design Guidelines 8. The full set of guidelines include:
-
Web Access: Why Is It Important? (in 2 pages or less)
A brief introduction to the issues around web access for executives
responsible for websites
-
Understanding Disabilities and Web Access Issues
A discussion of the different types of disabilities and their effect
on access to the web
-
A series of Check Lists
-
Checklist for web authors - about two printed pages
-
Checklist for user agent (browser) developers
-
Checklist for web server developers
-
Checklist for web tool developers
-
A series of Guidelines
-
Guidelines for web authors - about six printed pages
-
Guidelines for user agent (browser) developers
-
Guidelines for web server developers
-
Guidelines for web tool developers
-
The Unified Website Access Guidelines Central Reference Document
Presentation of web access issues along with solution strategies for
web authors, browser developers, server developers, and tool developers,
all in an integrated document so that the issues and the interactions between
the authors, browsers, and tools may most easily be seen.
-
Web Access Resource Site
A website containing extended discussions, case studies, demonstrations,
tools, references to other guidelines and efforts related to web access,
etc.
1.4 Simplifying the Guidelines
In putting together these guidelines, we have tried to keep
in mind that the simpler the guidelines were, the easier they would be
to understand and follow. Unfortunately, HTML, formatting, and the Web
are becoming increasingly complex. Also, browsers are introducing new elements
and options. These present both opportunities and complications. In addition,
we need to take into account the fact that although some of the pages out
there on the Web will be using the new features, there is still a legacy
of pages using old techniques, only a small portion of which will probably
ever be updated and reformatted. We are therefore trying to follow the
advice of Albert Einstein, who said "Everything should be made as simple
as possible, but no simpler." This first draft is an attempt to reach our
objective. In it, we have tried to incorporate all of the new information
and strategies, and to present them in as straightforward and useful a
fashion as possible. Our goals in this first version are therefore: correct,
complete, simplify, in that order. In fact, since this set of guidelines
is being used as a central reference point by so many, we need to always
maintain that order. However, we recognize the need for simplicity, and
that will be a primary focus, particularly of the short form and checklist
versions.
C2S2 Approach
The Trace Center has also launched what they call a "C2S2 Project."
This stands for the "Comprehensive Cross-Segment Strategy Project." In
a nutshell, this project seeks to identify and define a way that different
industry segments (authors, user agent [browser] developers, and assistive
technology developers [e.g., screen reader manufacturers]) can coordinate
their efforts. The goals of this cooredination are:
-
To minimize the effort needed by page authors to make their sites accessible.
-
To maximize the flexibility and creativity of page authors to create web-based
environments.
For example, currently, page authors have to follow several rules that
are not necessary if some basic capabilities or options were built into
browsers and screen readers. C2S2 seeks to work with all of the segments
to identify a cooperative strategy that divides up the access issue and
identifies ways that the different industry segments could cooperate to
minimize the number of guidelines and amount of effort needed. These guidelines
reflect and help support the C2S2 approach by identifying, under each issue,
the strategies and approaches that could be taken by all of the industry
segments to help address the access issue. More information on the C2S2
project is available at http://trace.wisc.edu/docs/c2s2/c2s2.htm.
1.5 Input Requested
As always, any and all comments on this draft are solicited.
This 8 series, however, will formally freeze on November 10. At that point,
the guidelines in their current form will be formally transferred to the
WAI, which will then, per previous decision, use them as a basis for developing
the formal WAI guidelines. Once the W3C/WAI guidelines are released, these
guidelines will be archived and website authors will be directed to the
W3C/WAI guidelines.
2. Introduction to Web Site Accessibility
2.1 Profiles of users with disabilities
Sensory disabilities - vision, audition
Low vision - There are many types of low vision,
including poor acuity, tunnel vision, clouded vision, floaters in the eye,
peripheral vision, etc. Some people with low vision need to enlarge the
text fonts and images, and may use use a dual (i.e., partial) or full screen
magnifier.
Note, low vision users may still encounter difficulty deciphering information
on the computer screen even when magnified due to:
-
magnifying small fonts or images may cause pixelation and/or distortion
;
-
magnified areas tend to loose contextual information (tunnel vision effect
doesn't allow user to "see" what information or choices are around the
magnified area).
Blindness - People are legally blind when they have less
than 20/200 vision in the better eye after correction, or less than a 20
degree field of view in the better eye after correction. Individuals who
are blind rely primarily on screen readers to read the text on the screen.
For graphic elements, they rely on the presence of a text description of
the image (and any text that is included as an image in the document).
Hard of hearing - A person whose hearing is less severely
impaired than deafness is said to be hard of hearing.
Deafness - A person is considered deaf when sound must
reach at least 90 decibels to be heard at all and even amplified speech
cannot be understood. Normal conversation is approximately 40 to 60 decibels.
Physical disabilities - paralysis, fine-motor
skills
There is a tremendous variety of physical disabilities. In
addition to the usual range from minor to severe involvement, there are
also many different types of physical disabilities. In order to better
understand its breadth, it is useful to break this category into two major
areas: neuromuscular and skeletal. Neuromuscular impairments include any
impairments that relate to the nervous system (including the brain) or
the muscles. For example, most speech impairments fall into this area.
Skeletal impairments relate to the bones, joints and missing limbs.
Although there are many specific types of neurological impairments,
their effects can be characterized as variations or combination of:
-
Paralysis - This lack of any muscular control and often sensation in part
of the body. This is usually caused by a break in the nerves leading to
the muscle, often in the spinal cord.
-
P aresis - Weakness or inability to produce small, controlled or forceful
movements. This can be caused by problems with the signals sent to the
muscles via the nerves, problems with the muscles themselves, or problems
due to pain when movements are made (as in the case of severe arthritis).
-
Interference with Control - This interference can take different forms.
The term spasticity is used if the muscles are tense and contracted and
voluntary movements is very difficult. Ataxia refers to problems in motor
programming and coordination. Athetosis and Chorea refer to constant or
uncontrolled motion (i.e. extra, involuntary movements).
Cognitive disabilities - learning, attention
deficit
These disabilities result from some type of damage to the human
brain. Therefore it is not surprising that there is a great complexity
of impairments in this category. Cognitive disabilities can be divided
into the following seven categories:
-
Impairments of Intelligence and Thinking
-
Mental Retardation
-
Dementia
-
Impairments of Memory
-
Amnesia
-
Memory illusions
-
Forgetfulness
-
Other Intellectual Impairments
-
Aphasia
-
(Specific) Learning Disabilities
-
Spoken language
-
Written language
-
Arithmetic
-
Reasoning
-
Psychological impairments
-
Drug and Alcohol Dependence
3. [Place holder for "On SGML and HTML"]
4. Definitions and Conventions
4.1 Definitions
Assistive Technologies
Assistive technologies are products used to help people accomplish
tasks that they can not accomplish otherwise. For example, eyeglasses assist
those of us who can not see clearly. When dealing with computers and the
world wide web, assistive technologies usually refer to software adaptations,
specially designed hardware devices, and/or standard devices used in alternative
ways which provide user access.
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 only read text that is printed, not painted, to the screen.
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.
ShowSounds and SoundSentry
Individuals who are deaf or hard-of-hearing can set the "ShowSounds"
and "SoundSentry" flags on some operating systems such as Windows95/NT.
If the SoundSentry flag is set, whenever the computer makes a sound, a
user chosen visual indication is provided on the screen. Any programs which
have significant aural or spoken content should check to see if the ShowSounds
flag is turned on. If it is, these programs should also provide all significant
aural content in a visual format (e.g., closed captions).
Scanning Software
Software that highlights (and/or announces) selection choices
(e.g. menu items, groups of possible phrases, etc.) one at a time. A user
selects a desired item by hitting a switch when the desired item is highlighted/announced.
Used primarily by individuals with severe physical or cognitive disabilities.
Alternate Keyboards
Hardware/software devices that provide an alternate way of
creating keystrokes that appear to be coming from the standard keyboard.
On-screen keyboards, speech input, eyegaze keyboards, and sip-and-puff
(Morse code) keyboards are some examples. Used primarily by individuals
with disabilities that prevent them from using the standard keyboard (and
usually from using the mouse as well). Programs that can be operated entirely
from the standard keyboard (and don't require the mouse) can be used by
individuals with alternate keyboards.
Braille and Dynamic Braille
Braille is a technique involving six dots which are raised
in different patterns to represent letters and numbers so that they can
be read by people who are blind using their fingertips. Grade II braille
includes additional codes that represent common letter groupings (e.g.,
"th," "ble") to make braille more compact. An 8-dot version of braille
has been developed to allow all ASCII characters to be represented. Dynamic
braille involves the use of a display where dots can be raised and lowered
dynamically to allow any braille words to be displayed. Only letters and
numbers can be represented in braille, although some braille printers have
a utility that allows simple graphics to be drawn on a sheet using the
raised dots at a resolution of approximately 11 dots per inch.
The word "Accessible" in Braille.
The word "Accessible" in Grade II Braille.
4.2 Types and encoding of recommendations
Rating System
[Required] - Required
for some groups of users to access the information on a page.
[Recommended] - Makes page easier to understand
and use.
Classification System
[Interim] - Strategies needed to make pages accessible
for today's browsers and assistive technologies
[New] - Strategies that will take advantage of new features being
incorporated into supported tomorrow's browsers and assistive technologies
(which incorporate Web Access Initiative recommendations).
If a recommendation has several possible strategies, the strategies
are classified, if not the recommendation itself is classified. Those
recommendations and strategies that have no classification work for both
old and new browsers.
Recommendations for different groups
There are several pieces of the puzzle that need to be put
together for a single page to be accessible. This document focuses mainly
on what page authors should be doing to ensure that browsers render the
page as maximally accessible as they can. We do offer suggestions for browser
and assistive technology designers, and even a few hints for users. The
following headings are used throughout the document:
-
Recommendations for page authors - issues
to be handled in source documents
-
Recommendations for user agent (browser) designers
- issues to be handled by browsers
-
Recommendations for Assistive
Technology designers - issues to be handled by screen readers, screen
magnifiers, scanning software, etc.
-
Suggestions for Users - configuring
the user agent and assistive technology for maximum benefit.
5. [Place holder for "HTML Document Representation"]
6. [Place holder for "Basic HTML data types"]
7. The global structure of an HTML
document
The HEAD and BODY of a document
7.1 Page Titles
Issue: Meaningful titles should be associated
with each page not only because they are required in HTML 4.0, but users
will more easily identify bookmarked pages. Most browsers will use the
address of a web page if no title is provided.
Recommendations for page authors
Design Tip: Use the TITLE
element in the HEAD of each
document.
For example, <HTML><HEAD>...<TITLE>Version
8 of the Unified Web Accessibility Guidelines</TITLE>...</HEAD>...
7.2 Metadata
There are many recent developments on this front that are
still being discussed. Hopefully, in the near future, authors will be able
to associate a variety of metadata with their pages. Stay tuned.
8. Language information and text direction
International considerations for text
9. Text
Paragraphs, Lines, Phrases,
Punctuation and Symbols
-
9.1 text formatting
-
9.2 Acronyms
-
9.3 Punctuation, symbols and ASCII art
-
9.4 Text that changes or moves
9.1 Text formatting
Issues: There are four issues with the presentation
of text:
-
Authors often use color, font style (e.g. bold or italic) or font changes
to highlight certain words or to make a page easier to read visually (e.g.
headings are italicized, outdented, a larger font and bold). While
this often makes the page easier to read visually, it is either lost in
the aural presentation or makes the aural presentation confusing.
In some instances, important information is being conveyed through the
typographics used and is lost to the auditory user. The following
is an expansion of the issues:
-
Color, font or font size - These typographic attributes often highlight
a section of text. For example, to signify a heading, or to
emphasize an important statement. Since most screen readers read
all text in the same manner, no matter what visual attributes they possess,
the meta information given in the example is lost. Headings not only
make it easier to skim through a page, they signify that a major change
in context has just occurred and give the new context a "handle."
The loss of this information can make a document harder to understand.
-
Indentation - Indentation is usually used to order or to group items.
Most screen readers do not indicate how much space precedes or follows
text. The issues are discussed in greater detail
in the section on Lists.
-
Drop-caps, subscripts and superscripts. Current screen readers
might interpret words or letters as appearing on a separate line.
-
Users need to adjust text size for easier viewing if they have low
vision. Changing the text size often makes the page unreadable due to changes
in layout.
-
Although users can override the color settings of HTML pages to alleviate
poorly contrasting colors, formats such as Portable Document Format
(PDF) prevent this. Also, some users may not yet be aware that they have
this ability.
-
Screen reading software cannot make sense of bit-mapped text since it is
perceived as graphical information. One of the most common examples of
bitmap text is the counter that records the number of accesses to a certain
page. For example, a text-only browser or screen reader might say the word
"image" when it encounters a graphic. Reading a page with a
graphical counter would sound like, "You are visitor number (image) to
visit this site" or "The number of visits to our site this month is (image)."
Elements affected: EM, STRONG, DFN, CODE, SAMP,
KBD, VAR, CITE, BLOCKQUOTE, Q, IMG, FONT, SUB and SUP
Recommendations for page authors
[Required]
Use style sheets: [New]
-
to create drop caps, subscripts and superscripts
-
to highlight sections of a document with font size, formatting or
color
-
rather than converting text to images or alternative text file formats
(such as PDF)
-
[Recommended]
Use logical styles rather than physical
markups. Do no misuse logical elements.
Logical: DFN, EM, CITE, CODE, KBD, SAMP, STRONG, VAR, H1,
H2, etc.
Physical: size=14, B, I.
This makes it easier for users to adjust the look of the screen (e.g.,
larger print, color contrast, etc.) when they apply their own style sheets
or for browsers to adjust the presentation of the document based on user
settings. The other advantage of logical elements is that they help enforce
consistency in your documents. It also leaves open the possibility
for more sophisticated uses of the semantic encodings in the future.
For example, the Lycos indexing system can take advantage of semantic encoding
to create abstracts of documents. Alternatively, browsers can navigate
through a document by logical styles, such as headers. Only use logical
elements for what they represent. For example, avoid using <cite>
to undent a paragraph.
-
[Recommended]
Avoid using the BLINK and
MARQUEE elements. [Interim]
Use another method to draw attention to text such as text size or color.
-
[Recommended]
Properly nest headings. (Use style
sheets for formatting [New] ).
Users with dyslexia may have problems reading long pages and will be
helped if the design facilitates scanability by proper use of headings.
This also benefits us all, as we scan through pages via the headings. Tagging
these correctly means that user agents can provide navigation through the
structure.
Testing tips
-
To test if the text and background contrast is sufficient enough to be
read by people with color deficiencies or on low resolution monitors, view
your pages with a monochrome monitor.
-
To get a better understanding of what a screen reader would present to
a user, do not load the images on a page when viewing with a graphical
browser or use a text-based browser such as Lynx.
Recommendations for user agent (browser) designers
-
Allow user-selected
style sheets to override the page author's settings.
-
Support navigation
between different size "chunks." For example, allow the user to jump
between links, or level 2 headings, or by sentence, or whatever they choose.
Recommendations for assistive technology designers
If user agents do not support the previous recommendation,
then that functionality should be implemented here (although this requires
parsing of HTML).
Suggestions for users
-
Make use of existing (or create your own) Aural Cascading Style Sheet (ACSS)
to interpret the page constructs as you desire.
-
To translate PDF files, download Adobe's plug-in for windows or retrieve
documents through their proxy. For more information, go to the Adobe site
at http://access.adobe.com/.
9.2 Acronyms
Issue: Acronyms may be unfamiliar to readers
or interpretted incorrectly based on previous experience. For example,
"CID" can stand for "Central Institute for the Deaf, " "Charge Injection
Device," "Computer Integrated Design," or "Configuration/Installation/Distribution"
depending on your context. For disability access, screen readers
may not recognize the phrase as an acronym and might make a best guess
at pronouncing it. Not only can this sound ridiculous, it can be
confusing.
Element affected: ABBR
Recommendations for page authors
Design Tip: Use the "title" attribute for
acronyms and abbreviations <abbr>title="World wide web">WWW</abbr>
Recommendations for user agent (browser) designers
Make
title information available or present it inline if requested
by the user.
9.3 Punctuation, symbols and ASCII art
Issue: Screen reading software will often
either ignore or read each name for punctuation used to make an emoticon
or ASCII art. For example, the smiley emoticon :-) would either be
ignored or read as "colon dash close parentheses."
Text symbols affected: all punctuation and letters that are used
to make emoticons, symbols or ASCII art
Recommendations for page authors
Design Tip: Avoid using ASCII art or replace it with
an image and alternative text.
Common typographic characters or constructions to be avoided are emoticons,
arrows consisting of dashes and greater than signs -->, etc..
9.4 Text that changes or moves
Issue: Text that changes or moves is either
read incorrectly or not at all by screen readers, can adversely affect
people with cognitive disabilities, and is often annoying to people in
general (see Jared Spool's book, "Web Site Usability"). For example,
a user with attention deficit disorder might find it hard to focus on the
rest of a page while blinking or scrolling text is present. Another example,
marquee text, is often read by most current screen readers (which do not
interpret the HTML) one letter at a time as it appears on screen. Therefore,
the visible words and characters of the message will be repeated each time
a new letter appears. For example, the message "Have a nice day,"
scrolling left to right:
Message that is visible on screen |
What is read to the user |
H |
"H" |
Ha |
"Hah" |
Hav |
"Have" |
e a nice day |
"E A nice day" |
Elements affected: BLINK, MARQUEE, as well
as programming or scripting languages, such as Java and JavaScript.
Recommendations for page authors
-
[Required]
Provide a mechanism for the user
to freeze any moving or blinking text.
In the following example created by Mark Novak, if the user presses
the escape key while the Java marquee has focus, the text will be displayed
statically. View
the example.
-
[Recommended]
Avoid using the BLINK and
MARQUEE elements. [Interim]
Use another method to draw attention to text such as text size or color.
Recommendations for user agent (browser) designers
Allow
users to view BLINK and MARQUEE phrases as static text.
This goes for all animations and interactions. See the sections on
Applets and Scripts
for more information.
Side note: MARQUEE is a MSIE3.0 element, while BLINK
was introduced in Netscape 1.1. Therefore, neither are considered
standard HTML.
10. Lists and Outlining
Unordered, Ordered, and Definition Lists
10.1 Helping users navigate lists effectively
Issue: Non-visual
users often "get lost" in lists, especially those with several layers of
embedding and those which lack discernible cues to indicate the specific
level of indentation for each item. In addition, it is often difficult
for non-visual users to know where the list itself begins and ends and
where each list item starts. Further, if a list entry wraps to the
next line, it may appear to be two separate items in the list.
For example, imagine stripping the indentation
and bullets from a list of items I keep in my desk:
-
writing utensils.
-
erasers
It might be read like this by a screen reader:
writing utensils.
pens
highlighters
red
green
blue
ball-point
green
purple
blue
pencils
#2 lead
soft lead
erasers
Elements affected: OL, UL, LI, DL, DD, DT, BLOCKQUOTE
Recommendations for Page Authors
-
[Recommended]
Correctly encode list structure and
list items with proper HTML elements (UL, OL, LI). (Use style
sheets to adjust item spacing [New]).
-
This is an ongoing topic of discussion, stay
tuned for developments.
Tips and tricks:
-
Using a numbered (ordered) list makes it easier for people accessing the
page auditorally to keep track of where they are within a list.
Recommendations for user agent (browser) designers
-
Introduce
each list by indicating how many items it contains.
For example, "There are 6 subtopics." or "7 Objectives of this study
are:". This information is helpful in orienting users as to how long a
list is that they are about to read. Numbering lists also addresses
cognitive disabilities. The organization in a page with numbered
lists and an indicator of the upcoming page structure helps someone's understanding
of a Web page.
-
Allow the user to configure how nested lists
should be enumerated and presented.
This includes allowing the user to choose to view all text in a left-justified
format if they so desire or to associate an aural cue with different levels
(via alternate aural cascading style sheets).
11. Tables
11.1 Comprehension and navigation of table
elements
Issue 1: Newspaper columns. Tables
are often used to layout pages of text in newspaper columns. Most
current screen readers (which do not interpret the HTML) read all the way
across the page reading sentences on the same row from different columns
as one sentence.
For example:
There is a 30% chance of rain |
Classes at the University of Wisconsin |
showers this morning, but the |
will resume on September 3rd. |
weekend looks like it will be sunny. |
|
This might be read by a screen reader as:
There is a 30% chance of rain Classes at the University of Wisconsin
showers this morning, but the will resume on September 3rd.
weekend looks like it will be sunny.
Issue 2: Spreadsheets and calendars. Tables
are often used to layout text and numbers. The screen reader may
append all of the numbers from different columns in the same row into one
large number if spaces and punctuation are not provided.
Issue 3: Alt-text that wraps. If the alt-text
of graphics laid out in a table wrap, then the "column effect" described
above will occur, making the table difficult or impossible to decipher.
For example, tables are often used to layout graphics to create navigation
bars. In this instance the alt-text for an image might be wrapped
to fit the width of the column that it is placed in. The following
table represents what a reader might see if images were not viewed on an
example opening page:
Welcome to our
site |
|
Sponsored by
XYZ company |
Help |
Search |
Products,
projects and
research news |
Virtual tour of our
headquarters |
Games and
educational
offerings |
Employment
opportunities |
Background |
Since each of these cells represents a graphic, and each graphic
is a link to another page, a user tabbing through the page might hear:
"Welcome to our" [tab] "Sponsored by" [tab] "site" [tab] "XYZ company"
[tab] "Help" [tab] "Search" [tab] "Products" [tab] "Games and" [tab] "project
and" etc.
Issue 4: In all of these instances, it is very difficult
to comprehend the semantics of the table since navigation through a table
with most current screen readers (which do not interpret the HTML) is so
limited. The user is forced to navigate by sentence, without
the options to navigate by row, column or cell.
Elements affected: TABLE, CAPTION, THEAD, TFOOT,
COLGROUP, TBODY, TH, TD, TR, and their attributes
Recommendations for page authors
-
[Required]
Explicitly associate table cells with row and column labels.
[New]
Future browsers and assistive technologies will be able to automatically
translate tables into linear fashions if tables are tagged appropriately.
-
"headers" - The following example, shows how to associate
header information with the "headers" attribute. The "headers" attribute
specifies a list of header cells (row and column labels) associated with
the current data cell. This requires each header cell to have an
"id."
<TABLE border="border" summary="This table charts the
number of cups of coffee consumed by each senator, the type of coffee (decaf
or regular), and whether taken with sugar.">
<CAPTION>Cups of coffee consumed by each senator</CAPTION>
<TR>
<TH id="t1">Name</TH>
<TH id="t2">Cups</TH>
<TH id="t3" abbr="Type">Type of Coffee</TH>
<TH id="t4">Sugar?</TH>
<TR>
<TD headers="t1">T. Sexton</TD>
<TD headers="t2">10</TD>
<TD headers="t3">Espresso</TD>
<TD headers="t4">No</TD>
<TR>
<TD headers="t1">J. Dinnen</TD>
<TD headers="t2">5</TD>
<TD headers="t3">Decaf</TD>
<TD headers="t4">Yes</TD>
</TABLE>
A speech synthesizer might render this table as follows:
Caption: Cups of coffee consumed by each senator
Summary: This table charts the number of cups of coffee consumed by
each senator, the type of coffee (decaf or regular), and whether
taken with sugar.
Name: T. Sexton, Cups: 10, Type: Espresso, Sugar: No
Name: J. Dinnen, Cups: 5, Type: Decaf, Sugar: Yes
-
"scope" - The following example associates the same header
and data information as the previous example, but uses the "scope" attribute
rather than "headers." "Scope" must have one of the following values:
row, col, rowgroup or colgroup. Scope specifies the set of data cells
to be associated with the current header cell. This method is particularly
useful for simple tables.
<TABLE border="border"
summary="This table charts the number of cups of coffee consumed
by each senator, the type of coffee (decaf or regular), and whether taken
with sugar.">
<CAPTION>Cups of coffee consumed by each senator</CAPTION>
<TR>
<TH scope="col">Name</TH>
<TH scope="col">Cups</TH>
<TH scope="col" abbr="Type">Type of Coffee</TH>
<TH scope="col">Sugar?</TH>
<TR>
<TD>T. Sexton</TD>
<TD>10</TD>
<TD>Espresso</TD>
<TD>No</TD>
<TR>
<TD>J. Dinnen</TD>
<TD>5</TD>
<TD>Decaf</TD>
<TD>Yes</TD>
</TABLE>
-
[Required]
Avoid using tables or <PRE>
elements to arrange text documents in columns or otherwise layout a page.
(Use style sheets to position graphics and text [New]).
-
[Recommended]
Provide abbreviations for lengthy row or column labels.
[New]
Abbreviations should be short but meaningful. This will be particularly
useful for future speaking technologies that will read row and column labels
for each cell. Abbreviations cut down on repetition and reading
time. Refer to the examples given in the appendix.
-
[Recommended]
Provide summaries of tables. [New]
Summaries of table structure and purpose are especially useful for
non-visual users. Refer to the examples given in the appendix.
-
[Recommended]
For more complex tables, group information into categories.
[New]
Future browsers will allow users to select data from a table by asking
for categories. For example, a table contains information about several
trips a person has recently made. One of these trips is to San Jose.
Information on expenses for meals, hotels and transportation are recorded
(each in their own column). There are several locations (San Jose,
Seattle, Madison). The expenses can be grouped into an "Expenses"
category and all of the locations into a "Location" category. The
following question could then be asked, "What were all of my expenses in
San Jose?" This means "What are all the data cells in the "Expenses=Meals,
Hotels, Transport" and "Location=San Jose" categories?
The following example shows how to create categories within a table.
<TABLE border="border">
<CAPTION> Travel Expense Report </CAPTION>
<TR>
<TH></TH>
<TH id="a2" axis="expenses">Meals</TH>
<TH id="a3" axis="expenses">Hotels</TH>
<TH id="a4" axis="expenses">Transport</TH><TD>subtotals</TD>
</TR>
<TR>
<TH id="a6" axis="location">San Jose</TH>
<TH></TH><TH></TH><TH></TH><TD></TD>
</TR>
<TR>
<TD id="a7" axis="date">25-Aug-97</TD>
<TD headers="a6 a7 a2">37.74</TD>
<TD headers="a6 a7 a3">112.00</TD>
<TD headers="a6 a7 a4">45.00</TD><TD></TD>
</TR>
<TR>
<TD id="a8" axis="date">26-Aug-97</TD>
<TD headers="a6 a8 a2">27.28</TD>
<TD headers="a6 a8 a3">112.00</TD>
<TD headers="a6 a8 a4">45.00</TD><TD></TD>
</TR>
<TR>
<TD>subtotals</TD><TD>65.02</TD><TD>224.00</TD><TD>90.00</TD><TD>379.02</TD>
</TR>
<TR>
<TH id="a10" axis="location">Seattle</TH>
<TH></TH><TH></TH><TH></TH><TD></TD>
</TR>
<TR>
<TD id="a11" axis="date">27-Aug-97</TD>
<TD headers="a10 a11 a2">96.25</TD>
<TD headers="a10 a11 a3">109.00</TD>
<TD headers="a10 a11 a4">36.00</TD><TD></TD>
</TR>
<TR>
<TD id="a12" axis="date">28-Aug-97</TD>
<TD headers="a10 a12 a2">35.00</TD>
<TD headers="a10 a12 a3">109.00</TD>
<TD headers="a10 a12 a4">36.00</TD><TD></TD>
</TR>
<TR>
<TD>subtotals</TD><TD>131.25</TD><TD>218.00</TD><TD>72.00</TD><TD>421.25</TD>
</TR>
<TR>
<TH>Totals</TH><TD>196.27</TD><TD>442.00</TD><TD>162.00</TD><TD>800.27</TD>
</TR>
</TABLE>
-
[Recommended]
Ensure that alternative text does
not wrap within tables used to position graphics. [Interim]
Test for wrapping using the equivalent window size as that which can
maximally fit on a 15-inch monitor using a common resolution such as 800x600
pixels.
-
TBD
For tables of text and numbers, provide
an alternative page which presents the table information in a linear fashion.
[Interim]
There are several ways to link to alternate pages which are described
in more detail in Methods for linking to alternate
pages.
-
[Recommended]
Provide a phone or fax number or
e-mail address if tables can not be made accessible.
Testing tips
-
To predict how one of today's screen readers might read your table, hold
a piece of paper up to your monitor. As you slide the paper down
the monitor, read the words above the line the paper creates as a
sentence. Ask another person to listen as you read the page out loud
without pausing for column gaps. Can he or she make sense out of
what you have read?
-
Another method, to predict how a screen reader will interpret your page,
is to save it as a text-only file then open it with a word processing program.
This function is available in the "File" menu in most browsers.
Recommendations for user agent (browser) designers
-
Make cell, row
and column information available.
Semantic information is provided through attributes available for each
entry in the table, the row and column information as well as the cell's
data contents. This will most likely emerge in the next HTML 4.0 specification
as AXES, AXIS, and SCOPE attributes. As the
draft solidifies we will provide more information about how to use the
new attributes.
-
Provide methods
to "unwrap" table information.
How a table is unwrapped will be determined by which attributes are
added to HTML 4.0. There has been considerable discussion about this in
the WAI working groups and we will update this recommendation as soon as
it is resolved.
Recommendations for assistive technology designers
-
Provide the
ability to navigate by column, row and cell.
-
Provide orientation
functions.
To help the user determine which row or column they are in, and to
establish how the current cell contents relate to the rest of the table,
a "where am I" feature is needed.
12. Links
Hypertext and Media-Independent Links
-
12.1 Links read out of context
-
12.2 Identifying links within a sentence
-
12.3 Several links read as one
-
12.4 Methods for linking to alternate pages
-
12.5 Use of graphics decreases cognitive
load and increases target area.
-
12.6 Page abstracts
-
12.7 Keyboard shortcuts for links
12.1 Links read out of context
Issue: People who use screen readers to access
the information on the web will often use the tab key to step through the
links on a page. Although this allows users to more quickly identify links,
they will not hear the surrounding text and will lose the context of the
link. Pages that use the same phrase for several different links (e.g.
a series of "click here's") are impossible to navigate solely by reading
the links. Microsoft Internet Explorer 4.0 can create an overview of a
page by presenting a list of just the links on the page. This might become
a popular method to scan pages by everyone.
Element affected: A
Recommendations for page authors
[Recommended]
Create link phrases that make sense
when read out of context (but they are not too verbose).
A user should be able to select a link from a list of all of the links
on a page without reading the context in which the link was used. For example,
using "click here" as the text phrase for several links requires a user
viewing the page with a screen reader to scout out each link to determine
the context before selecting one. However, replacing "click here" with
something more descriptive solves this problem. For example, "download
this document in ASCII text," "view the full version in HTML," or "to view
the text version, click here."
Recommendations for user agent (browser) designers
-
Provide a feature
that displays either:
-
A list of links
-
A list of links which each link followed by its surrounding text.
For example, click here; To
find out more about how the west was won, click here.
-
OR A list of headers and links
12.2 Identifying links within a sentence
Issue: It is difficult for users of screen readers
to identify links included within a sentence since there are no aural differences
of how links are read versus other words. Visual users are able to detect
links by color coding and underlining.
Recommendations for user agent (browser) designers and/or assistive technology
designers
Provide
an option to insert a character(s) or a blank line before each link or
associate an aural cue with links.
Characters are one way of associating an aural cue with links, since
it will be spoken by those using screen readers. However, this cue usually
does not help determine where the link ends whereas a sustained background
sound that is played during the reading of a link or a change in the pitch
of the voice would.
12.3 Several links read as one
Issue: Currently, lists of links are sometimes
read as one link by most current screen readers (which do not interpret
the HTML). Sometimes this happens even when the links are on different
lines. The user is unable to position the mouse cursor on any of the specific
links, making the links inaccessible.
Recommendations for page authors
[Recommended]
Place non-link, printable characters
(surrounded by spaces) between links which occur consecutively
to keep separate links from being read as one by screen readers. [Interim]
Recommendations for assistive technology designers
Links should be spoken separately with pauses in between.
12.4 Methods for Linking to alternate
pages
Issue : Oftentimes an alternate version
of a page is available as a link from the current page. Alternate
pages can be text-only versions of a page, the page translated to another
language, or a more succinct presentation of the information.
When creating text-only versions of pages, there are several issues
to be aware of:
-
The text-only page might link back to a graphic-intensive page, which has
an alternative link for a text-only page. This hopping back and forth
can dramatically increase the time required to navigate the site.
Especially if the link for the text-only version is buried in the page.
-
It is easy to see that creating text-only versions of every page on a site
could double the number of pages that need to be maintained. Three methods
for generating and maintaining text-only pages are described in the section
Methods to create alternate pages found in
Appendix A. Some of these methods generate text-only pages automatically.
Methods for page authors
-
Provide a visible link at the top of each page to allow a user to move
back and forth between the graphic and alternate versions of the page,
if they wish to do so. [Interim]
-
Provide the appropriate information in the header of the page so that
the browser loads it automatically. [New]
If the user has set his or her default media type to "speech" this
will load the alternate page automatically:
<HEAD><LINK title="Text-only version" rel="alternate" href="text_only.html"
media="speech"></HEAD>
Recommendations for user agent (browser) designers
Allow users to select a default media type (screen, print, projection,
braille, or speech).
If a page is specifically created for their selected default media
type, load the appropriate page automatically.
12.5 Use of graphics decreases cognitive
load and increases target area
Issue: For web-surfers with some degree of motion
impairment, selecting text links can be difficult because of the small
target area and dexterity needed to select them with a mouse pointer. Therefore
they, along with people with cognitive disabilities and people who cannot
read well, often find that photos and graphics/icons make it easier to
navigate and comprehend a site. While the use of graphics poses problems
for users with visual disabilities, it may make it more obvious for someone
else who has difficult reading and/or understanding the content. To learn
more about how to make images accessible to people with visual disabilities,
see the section Viewing and interacting with images
and image maps. Keep in mind that the design of effective icons is
not a trivial task due to the variety of possible interpretations by people
based on personal differences.
Recommendations for page authors
-
Design Trick: Provide hyperlinks that use enlarged font sizes or graphical
buttons to make the target area larger.
However, make sure that you follow the guidelines for style sheets
and alt-text so that you do not cause problems for people with visual disabilities.
Recommendations for user agent (browser) designers
-
Support "tabbing"
between links.
-
Allow the user
to select font color and size of text links.
-
Consider creating
a bookmark function that allows a person to associate a picture with
each bookmark.
Selecting a favorite page then becomes a matter of locating the image
they associate with it.
12.6 Page abstracts
Issue: It seems that it would be beneficial if
metadata information could be stored with a link or retrieved separate
from the entire page to provide a better picture of where the user is headed.
Some information that might be helpful is a description of where the page
going to, size of the page, purpose of the link, author, etc. Or, the creation
of a page "abstract" that could be retrieved and viewed before the whole
page was loaded.
Recommendations
There are no recommendations at this time. Further exploration
is needed and solutions solicited.
12.7 Keyboard shortcuts for links
Design Trick: Provide keyboard shortcuts for links.
The "accesskey " attribute of <LABEL>, <A>, <CAPTION>
and <LEGEND> allows an author to associate a keyboard shortcut
with the phrase. For example, when associated with a link, it takes the
user to the associated document. <A accesskey="C" href="doc.html">Press
C to go to XYZ page</A>
13. Objects, Images, Audio, and Applets
Multimedia in HTML documents
-
13.1 Introduction to the issues
-
13.2 In general
-
13.3 Viewing and interacting with static images and
image maps
-
13.4 Viewing and interacting with applets
-
13.5 Audio and video
13.1 Introduction to the issues
Multimedia provides the greatest number of barriers for the
greatest number of people for the following reasons:
-
Some users are unable to see images, movies or other types of animations
CLEARLY either because they are colorblind, they have low vision, or
they do not have a high resolution display.
-
Some users are unable to view images, movies or other types of animations
AT ALL either because their eyes are currently busy (they are driving),
they do not have the proper software, have text-based software, have a
slow data connection, are blind or very low vision, or they are accessing
the information via phone interface.
-
Some users are unable to hear movie sound tracks, audio clips or other
types of audio information because they work in a loud environment
(and the computer noises are masked by the environmental noises), work
in a quiet environment (and need to turn the speakers off so as not to
disturb others), do not have the proper software, hardware or enough memory
to run the software, have a slow data connection, or are deaf or hard of
hearing.
13.2 General Recommendations
The following recommendations apply to images, sounds and multimedia.
Elements affected: OBJECT, IMG, APPLET, A
Recommendations for page authors
-
Background
patterns and color should contrast well with the lettering to maintain
readability (background refers to both backgrounds of pages and backgrounds
of images).
-
Avoid using similar hues together. For example, do not place blue-green
lettering on a blue background. Dark shades of blue, violet, purple or
black lettering on backgrounds of light shades of blue-green, green, yellow
or orange are easiest to read. For more information on color contrast for
people with low vision and color deficiencies contact The Lighthouse, Inc.
for their pamphlet Color Contrast and Partial Sight [(800) 334-5497]
which is also available on the web at http://www.lighthouse.org/1lh32a.html.
-
Design graphics with just 16 colors so that colors do not change
across platforms, i.e. it might be unreadable on a different platform.
-
Make
color coding redundant with other means of conveying information.
For example, distinguish glossary words with the color red as well
as with emphasis.
-
For
troublesome pages, link to an alternative page
Whenever you have trouble making a page directly accessible, provide
a second version of the page which replaces any graphics, applets, movies
or audio with text descriptions or transcripts and replaces buttons and
other active areas with text links. There are several ways to do this which
are described in more detail in Methods for linking
to alternate pages (in Appendix B).
Recommendations for user agent (browser) designers
-
Allow users
to designate whether they want to download and view multimedia and applets.
-
Display the
alternate media associated with the element if the user selects not to
view multimedia .
This includes:
-
Alternate text for images.
-
Alternate text for each link of an image map (client side).
-
Alternate renderings for objects included with the OBJECT element.
An HTML example is in the section on applets.
Then an applet, either a movie, a still image or text description could
be loaded based on the user's preferences.
-
Transcripts for movies.
-
Transcripts or descriptions of audio clips.
Suggestions for users
If you have a slow modem connection (14400 kbps or less), are
unable to see, or do not care to see multimedia or applets, your browser
should provide a way to select whether or not you wish to download this
information. Lynx and other text-based browsers do not support graphics
and you will not need to configure anything.
13.3 Images and image maps
Elements affected: OBJECT, IMG
Recommendations for page authors
-
[Required]
Provide alternative text for all images and image maps.
All images should have alternative text that describes the function
of the graphic. Examples of possible alt-text are, "Section Title: Banana
Products," "Graph of population versus age," or "Search Button."
Possible solution strategies include:
-
The "alt" attribute is mandatory for the <AREA> and
<IMG> elements, but should also be used for <APPLET>,
and <INPUT>. For example, <IMG SRC="logo.gif" alt="XYZ
Logo">.
-
[New] If <OBJECT>
is used, text can be provided in the body of the <OBJECT>
element. For example, <OBJECT data="logo.gif"> XYZ Logo </OBJECT>
Several tips and tricks concerning alternative
text are in the appendix.
-
[Required]
Provide a link to a longer description (i.e., via D-link,
or longdesc, etc.) for graphics that present important information (especially
charts, tables and diagrams). (Include internal text in image file formats
that support it).
Alternative text descriptions (recommendation #1) are usually short
and define the basic purpose of graphic elements. To describe the graphic
itself in more detail a link to a longer description should be provided.
-
[Interim] Provide a D-link next to the graphic that links to a page
or a phrase at the bottom of the page with a longer description of the
graphic. For example, <IMG SRC="97sales.gif" alt="Sales for 1997"><A
HREF="sales.html">D</A>
-
[New] Use the "longdesc" attribute of the <IMG>
element or provide text within the body of the <OBJECT > element.
For example, <IMG SRC="97sales.gif" alt="Sales for 1997" longdesc="sales.html">
The description found on the page "97sales.html" might read something
like: "This chart shows how many widgets we sold in each of our four regions,
North, South, East and West. In the North we sold 2,000 units. In the South
5,000 units. In the East 6,000 units and in the West 8,000 units."
WGBH pioneered the practice
of placing a capital "D" text link next to pictures or graphics which link
to a longer description of the graphic. Since the letter "D" is not a very
descriptive phrase for a link, if you use this method you should include
an explanation of what it represents and why. Another option is to use
a more descriptive text link, such as "or a description of xxx."
-
[Required]
Use client-side (instead of server-side) image maps.
Client-side image maps are similar to server-side image maps except
that the information for all of the "hot-spots" within the image are sent
to the browser along with the image map picture. Descriptions provided
with the URLs can be displayed rather than the graphic. If server-side
image maps can not be avoided, see the 5th strategy of the next recommendation.
-
[Required]
Provide a description for each link in an image map.
Depending on how you've created your image map you have several possibilities:
-
Use the "alt" attribute of the <AREA> element (with
the IMAGE, MAP and AREA elements)
<IMG src="welcome.gif" alt="Image map of areas in the library"
usemap="#map1">
<MAP name="map1">
<AREA coords="0,0,30,30" href="reference.html" alt="Reference">
<AREA coords="34,34,100,100" href="media.html" alt="Audio Visual
lab">
</MAP>
-
[New] Use the "alt" attribute of the <AREA>
element (with the OBJECT, MAP and AREA elements)
<OBJECT data="welcome.gif" usemap="#map1">
alt="Image map of areas in the library" </OBJECT>
<MAP name="map1">
<AREA coords="0,0,30,30" href="reference.html" alt="Reference">
<AREA coords="34,34,100,100" href="media.html" alt="Audio Visual
lab">
</MAP>
-
[New] Use the "title" attribute of the <A>
element (with the OBJECT and SHAPES elements)
<OBJECT data="welcome.gif" shapes>
Areas in the library
<A coord="0,0,30,30" href="reference.html" title="Reference">Reference</A>
<A coords="34,34,100,100" href="media.html" title="Audio Visual
lab">Audio Visual Lab</A>
</OBJECT>
-
[New] Create a descriptive paragraph within the <OBJECT>
element that includes the links (using the OBJECT and A
elements)
<OBJECT data="welcome.gif" shapes>
There are several areas in the library including <A coord="0,0,30,30"
href="reference.html">Reference</A> and <A coords="34,34,100,100"
href="media.html"> the Audio Visual Lab</A>. More text can
follow or precede.
</OBJECT>
-
If a server-side image map has to be used, provide a list of the
image map choices (links) as text links on the same page, on an alternative
page that is accessible, or within the body of the <OBJECT>
element (similar to method #4 above). To avoid confusion, if providing
the list of links following the image map, you should indicate within the
alt-text of the image map that this is so.
-
[Recommended]
Provide descriptive titles for all images used as links.
Use the "title" attribute of the <A> element to
provide more information about images used as links (usually a graphical
button). For example, <a href="home.html" title="XYZ company home
page"><IMG SRC="logo.gif" alt="XYZ logo"></A>
Recommendations for user agent (browser) designers
-
Calculate
the alt-text for the IMG element if not provided by the author.
When an author does not set the alt attribute for the IMG
element, user agents should supply the alternate text, calculated in the
following order:
-
If the title has been specified, its value should be used as alternate
text.
-
Otherwise, if HTTP headers provide title information when the included
object is retrieved, this information should be used as alternate text.
-
Otherwise, if the included object contains text fields (e.g., Portable
Network Graphics (PNG) images contain some text fields), information extracted
from the text fields should be used as alternate text. Since user agents
may have to retrieve an entire object first in order to extract textual
information, user agents may adopt more economical approaches (e.g., content
negotiation).
-
Otherwise, in the absence of other information, user agents should use
the file name (minus the extension) as alternate text.
-
Alt-text that
is displayed for image links should have the same font attributes as text
links.
If an image is a link to another page then the alt-text should be coded
just as other text links. The most common coding is blue and underlined.
This will ensure that users will be able to distinguish between decorative
or illustrative graphics and those that are links.
-
Load and display
long descriptions of graphics on command.
While a user is on a graphic, he or she should be able to issue a command
to pull up the long description of the graphic. Especially as the longdesc
attribute of IMG is supported or descriptions are included within
the graphic file. The description should be displayed surrounded by square
brackets in place of the graphic. If no description has been specified
for a graphic, the user should be notified of the error.
13.4 Applets
Since there are several full-fledged programming languages
with accessibility issues of their own, we leave the discussion for how
to make them accessible to other documents. Trace recently completed a
report commissioned by Sun to identify the accessibility issues with
Java. For more information on what JavaSoft is doing about accessibility
issues within Java, visit their Java Accessibility site at http://www.sun.com/tech/access/.
However, not all browsers support applets and some users do not want
to download them because of bandwidth or platform constraints. Newer browsers
support a preferences flag that allows the user to indicate if they wish
to view applets or not.
Recommendations for page authors
-
[Required]
Provide alternative text for all
applets.
-
[Interim] <APPLET code="Press.class" width="500" height="500"
alt="Java applet: how temperature affects pressure.">
As temperature increases the molecules in the balloon...
</APPLET>
-
[New] <OBJECT classid="Press.class" width="500" height="500"
title="Java applet: how temperature affects pressure.">
As temperature increases the molecules in the balloon...
</OBJECT>
-
[Required]
Provide descriptions of applets that
present important information.
-
[Interim] Use the <APPLET> element to provide a description
(see the previous example). Complete text descriptions could be substituted
for the "Hello World!" message.
-
[New] Use the <OBJECT> element (see the previous example).
Complete text descriptions and other accessible objects (see recommendation
#5) could be substituted for the "Hello World!" message.
-
[Required]
If an applet gathers information, provide an alternative
mechanism to gather the information.
As with the previous two recommendations, an alternative such as a
user-input form, e-mail address, phone or fax number could be provided
within the alternative text of either the <APPLET> or <OBJECT>
elements.
-
[Required]
If an applet requires a user interaction (e.g. the ability
to manipulate a physics experiment) that can not be duplicated in an alternative
format, make the applet directly accessible.
The guidelines for accomplishing this are included within the Java
Accessibility project, and are not yet complete.
-
[Recommended]
For applets embedded with the <OBJECT> element,
provide alternative, accessible presentations of information within the
<OBJECT> element body. [New]
In HTML4.0 the <APPLET> element has been replaced by the
<OBJECT> element. The <OBJECT> element supports
nesting of objects for alternative renderings. For example:
<!-- First, try the pressure applet -->
<OBJECT title="How temperature affects pressure" classid="Press.class"
width="500" height="500">
<!-- Else, try the MPEG video -->
<OBJECT data="pressure.mpeg" type="application/mpeg">
<!-- Else, try the GIF image -->
<OBJECT data="Pressure.gif">
<!-- Else render the description and an alternative exercise
-->
As temperature increases the molecules in the balloon...
</OBJECT></OBJECT></OBJECT>
-
[Recommended]
Make applets keyboard operable
(using
standard conventions).
Recommendations for user agent (browser) designers
-
Render alternatives
based on user preferences.
-
Calculate the
alt-text for the APPLET element if not provided by the author,
in the same way as suggested for IMG.
13.5 Audio and video
Beyond the accessibility issues, there are other practical
issues that support following these guidelines. For example, users may
want to print a transcript of the dialogue in a movie, search for a certain
section of an audio clip via keywords, or search for a particular video
clip using a search engine such as a web crawler. Associated captions and
transcripts makes these scenarios possible. If descriptions are provided
in text mode as well, you can index and search for any video information
which is contained in the descriptions.
Recommendations for page authors
-
[Required]
Provide a text transcript file for
all information presented auditorally.
A transcript is a textual representation of all dialogue, and audio
information.
-
[Required]
Provide descriptions of all video
information in an auditory form.
Audio descriptions of video action provide additional information
during breaks in the dialogue of a movie about the actions that are occurring.
-
[Required]
Provide a separate text transcript
file of all video descriptions.
A text transcript of video action provides the same information as
in recommendation #2 but in a format accessible to those with no audio
access.
-
[Required]
Synchronize transcript and video
description information with audio/video information, either directly or
via a synchronization file.
Some media formats such as QuickTime (for Macintosh) movies provide
alternative tracks that can be used to add captioning and video descriptions.
-
[Interim] Until the format you are using supports alternative tracks,
two versions of the movie could be made available, one with captions (and
descriptive video) and one without.
Example - QuickTime (for Macintosh): With QuickTime you can add
as many audio or video tracks as you wish. Users can then select as few
or as many of the tracks as desired when they view the QuickTime clip.
Tracks could include (in addition to the regular video and audio tracks):
-
A text track with captions
-
An audio track with video descriptions added
-
An additional video track with American Sign Language translation
-
Additional text or audio or video tracks spoken or signed in other languages
For more information on captioning and descriptions visit: http://www.boston.com/wgbh/pages/ncam/currentprojects/captionedmovies.html
-
[New] Future technologies will allow separate audio/visual files
to be combined with text files via a synchronization file to create captioned
audio and movies. It will also allow the user to choose from multiple sets
of captions to match their reading skills. For
more information see the SMIL specification.
-
TBD
Provide visual notification of sounds
that are played automatically.
This can be provided in the form of a text phrase on the page that
links to a text transcript or description of the sound file. The link to
the transcript should appear in a highly visible location like the top
of the page. However, if a script is automatically loading a sound, it
should also be able to automatically load a visual indication that the
sound is currently being played and provide a description or transcript
of the sound. The controversy surrounding this recommendation is that
the browser should load the semantic information instead of the auditory
if the user preferences are set to do so. However, how do we resolve this
so it will work with today's browsers.
-
Design Trick: Use the "TITLE" attribute to provide a brief
description within the link to very short sounds.
For example, <a href="mittens.wav"
title="meow"></a>
Recommendations for user agent (browser) designers
-
Support time
synchronized text (caption) files.
This implies providing the support to link three files (the audio,
the text transcript and the text synchronization files).
-
Provide a command
to load and display the text transcription/description file.
-
Visually display
aural alerts.
If the device has a ShowSounds/Captions feature then this indicator
could be tied to the ShowSounds/Caption Flag maintained by the system.
-
Display the
title attribute of links.
14. Style Sheets
Controlling the presentation of an HTML document
14.1 Style sheets solve several issues,
but only if users can override
Whereas most of the other areas present issues that create
problems, style sheets is one of the few areas where it generates more
solutions that problems. This assumes that the current specification
of HTML 4.0 is implemented as discussed in the most recent draft.
Elements affected: STYLE and its attribute
Recommendations for page authors
-
[Required]
Use style sheets to position text and objects within pages,
rather than physically marking up text and graphics (e.g. <B>
or the "align" attribute of <IMG>) (However, continue
to use logical elements such as STRONG, H1, etc. to provide
semantic coding within the body of the page) [New]
Use style sheets rather than:
-
converting text to images or alternative text file formats (such as PDF)
-
using tables or PRE elements to layout pages
-
using proprietary extensions
-
using "invisible" images to layout pages
-
writing a program to accomplish something that is possible with style sheets
or plain HTML
Use style sheets to:
-
position text and graphics
-
create drop caps, subscripts and superscripts
-
avoid uncommon typographic characters or constructions (such as ASCII art,
etc.)
-
create alternative versions of a page. Whether or not you anticipate your
page being viewed on alternative media, such as a PDA, a speech-based browser
or paper (printed), it is a good idea to create style sheets for alternative
media to facilitate readability. Example media types are screen,
print, projection, braille, and speech.
-
highlight sections of a document with font size, formatting or color
-
[Required]
Ensure that your pages are readable and usable without style
sheets (e.g. when the browser does not support or the user
prefers not to load). Since style sheets are a new phenomenon, older
browsers will not support them and it will take a while for new browsers
to support them in a standard way.
Recommendations for user agent (browser) designers
-
Allow users
to select which types of media style sheets they want to use.
-
Allow users
to override page author settings with their own style sheets.
Recommendations for assistive technology designers
Perhaps one of the best developments for AT designers will
be style sheets that work best with their products, especially aural style
sheets.
Suggestions for users
If you do not want to create your own style sheet, but would
like to ensure that pages will display appropriately on your viewing device,
you can retrieve a style sheet and set it as your default from one of the
emerging libraries of style sheets.
15. Alignment, font styles, and horizontal
rules
15.1 Providing additional cues
with horizontal rules
Issue: Horizontal rules (lines) visually indicate
changes in context or highlight a section of text. For example, in this
document we use horizontal rules between chapters and sections. Since screen
readers do not usually pronounce anything for horizontal rules these
cues changes in context go unnoticed. In this document we try to give as
many cues to the reader as possible. One strategy is to use numbers to
mark each chapter and associated section. Therefore when you read 16.4,
then come across 17 it should be easy to interpret that you have just started
a new chapter. To provide equal "warning" to the non-visual user we use
the title attribute of the
HR element.
Element affected: HR
Recommendations for page authors
-
Design Trick: Use the "title" attribute on horizontal
rules <hr title="new section">
16. Frames
Multi-view presentation of documents
16.1 Misinterpretation by screen
readers and small screen users
Issue: Today's screen readers often view
each frame as either a separate window or read across several of them as
they do tables (line by line across all frames). Other times, screen
readers get stuck in one frame. Also, when multiple frames are viewed on
small monitors it is often difficult or impossible to see all of the data.
Elements affected: FRAME, FRAMESET and NOFRAME
Recommendations for page authors
-
[Required]
Provide a <NOFRAME> option
for each <FRAMESET>.
When using the <NOFRAME> option it is easiest to include
all essential information on the bottom of the main frame. The following
example is taken from the HTML 4.0 specification.
-
If the user reads "top.html" and the user agent
is not displaying frames the user won't see anything since we do not have
a BODY in "top.html". If we
insert "table_of_contents.html" and "main.html" directly in a NOFRAMES
element in the FRAMESET, we
solve the problem of associating the two documents, but we may cause user
agents that support frames to retrieve the same data twice: one copy associated
with the FRAMESET and one
copy inserted in the NOFRAMES. It is more economical to include
the table of contents at the top of "main.html" within a NOFRAMES
element:
<!-- This is main.html -->
<HTML><BODY>
<NOFRAMES>
...the table of contents here...
</NOFRAMES>
...the rest of the document...
</BODY></HTML>
and to link to "main.html" from "top.html" for the case when frames
are not displayed:
<!-- This is top.html -->
<HTML>
<FRAMESET cols="50%, 50%" title="Our big document">
<FRAME src="main.html" title="Where it's all at">
<FRAME src="table_of_contents.html" title="Table of Contents">
<NOFRAMES>
Here's the <A href="main.html">for a non-frames version.</A>
</NOFRAMES>
</FRAMESET>
</HTML>
-
[Recommended]
Title each frame. [TOMORROW]
Notice the use of "TITLE" in the previous example. People
accesing the page aurally will more easily keep track of how many frames
exist and which is the current one.
-
[Recommended]
Describe the layout and purpose of frames and how multiple
frames relate to each other. [New]
Use the "longdesc" attribute on <FRAME> and <IFRAME>
elements to link to a page with descriptions.
Recommendations for user agent (browser) designers
Allow
the user to select whether they want to load frames or not. If
they do not, use the NOFRAME option provided by the page author
or the first frame defined as default.
Recommendations for assistive technology designers
Screen readers should be able to navigate each frame as a separate
window that is identified uniquely by the TITLE of each frame.
Suggestions for users
If you don't want to view frames, select the "NOFRAME" in your
user agent (TOMORROW), or use a text-based like Lynx which automatically
requests the NOFRAME (TODAY).
17. Forms
User-input Forms: Text Fields, Buttons, Menus, and more
-
17.1 Navigation and manipulation
-
17.2 Graphical buttons
17.1 Navigation and manipulation
Issue: Users who do not use a mouse (such
as screen reader users) or that do not use a mouse well (such as users
with mobility disabilities) are not always able to navigate into form elements.
Often, once they are able to focus on the form element they are unable
to manipulate it.
Elements affected: A, AREA, OBJECT, INPUT, SELECT,
TEXTAREA, and BUTTON.
Recommendations for page authors
-
[Required]
Do not use image maps to create graphical
"submit" buttons.
-
[Required]
Explicitly associate labels with
their control. [New]
For example:
<FORM action="http://somesite.com/adduser" method="post"
<FIELDSET>
<LEGEND align="top">Personal information</LEGEND>
<LABEL for="firstname">First name: </LABEL>
<INPUT type="text" id="firstname" tabindex="1">
<LABEL for="lastname">Last name: </LABEL>
<INPUT type="text" id="lastname" tabindex="2">
...more personal information...
</FIELDSET>
<FIELDSET>
<LEGEND align="top">Medical History</LEGEND>
...medical history information...
</FIELDSET>
</FORM>
-
[Required]
Provide alternative text for images
used as "submit" buttons.
For example, <INPUT type="image" name="submit" src="button.gif"
alt="Submit">
-
[Recommended]
Specify a logical tab order with
"tabindex".[New]
For example, (taken from the HTML 4.0 draft)
<INPUT tabindex="1" type="text" name="field1">
<INPUT tabindex="2" type="text" name="field2">
<INPUT tabindex="3" type="submit" name="submit">
-
[Recommended]
Group related controls with the <FIELDSET>
element.[New]
see the example for #2 - "Explicitly associate labels with their
control."
-
[Recommended]
Label a group of controls with the
<LEGEND> element. [New]
see the example for #2 - "Explicitly associate labels with their
control."
-
[Recommended]
For long lists of selections, group items into a hierarchy.
[New]
In the near future, browsers will display grouped lists with expanding
and collapsing levels of detail. To group items, use
<OPTGROUP> elements with a <SELECT>
element, such as:
<FORM action="http://somesite.com/prog/someprog" method="post">
<P><SELECT name="ComOS">
<OPTGROUP label="Comm Servers">
<OPTGROUP label="PortMaster 3">
<OPTION label="3.7.1" value="pm3_3.7.1">PortMaster 3 with ComOS
3.7.1
<OPTION label="3.7" value="pm3_3.7">PortMaster 3 with ComOS
3.7
<OPTION label="3.5" value="pm3_3.5">PortMaster 3 with ComOS
3.5
</OPTGROUP>
<OPTGROUP label="PortMaster 2">
<OPTION label="3.7" value="pm2_3.7">PortMaster 2 with ComOS
3.7
<OPTION label="3.5" value="pm2_3.5">PortMaster 2 with ComOS
3.5
</OPTGROUP>
</OPTGROUP>
<OPTGROUP label="Routers">
<OPTGROUP label="IRX">
<OPTION label="3.7R" value="IRX_3.7R">IRX with ComOS 3.7R
<OPTION label="3.5R" value="IRX_3.5R">IRX with ComOS 3.5R
</OPTGROUP>
</OPTGROUP>
</SELECT>
</FORM>
-
[Recommended]
Include default, place-holding characters
in edit boxes and text areas. [Interim]
-
[Recommended]
Include a phone number, e-mail address,
postal address or fax number for submitting information.
-
[Recommended]
Create keyboard shortcuts for form
elements. [New]
This example assigns "U" as the access key. Typing "U" gives focus
to the label which gives focus to the control then the user can input text.
<FORM action="submit" method="post">
<label for="user" accesskey="U">user name</label>
<input type="text" name="user">
</FORM>
Recommendations for user agent (browser) designers
-
Support the
accesskey attribute and FIELDSET and LEGEND elements included in the HTML
4.0 specification.
-
Allow users
to navigate to and manipulate all form elements via the keyboard.
-
Calculate the
alt-text for the INPUT element if not provided by the author.
When an author does not set the alt attribute for the INPUT element,
user agents should supply the alternate text, calculated in the following
order:
-
If the title has been specified, its value should be used as alternate
text.
-
Otherwise, if the name has been specified, its value should be used as
alternate text.
-
Otherwise (submit and reset buttons), the value of the type attribute should
be used as alternate text
-
Read labels
with their associated objects.
17.2 Graphical buttons
Issue: Forms can include images that act
as buttons or image maps to gather input. See the section that discusses
graphical links.
Recommendations for page authors
-
[Required]
Do not use image maps to create graphical
"submit" buttons.
-
[Required]
Provide alternative text for images
used as "submit" buttons.
For example, <INPUT type="image" name="submit" src="button.gif"
alt="Submit">
18. Scripts
Animated Documents and Smart Forms
-
18.1 Introduction to the issues
-
18.1.1 Action occurring away from
user focus
-
18.1.2 Actions executed during load
of page
-
18.1.3 Automatic update of page ("push")
-
18.1.4 Summary of issues
18.1 Introduction to the issues
A client-side script is a program that may accompany
an HTML document or be embedded directly in it. The program executes on
the client's machine when the document loads, or at some other time such
as when a link is activated. HTML's support for scripts is independent
of the scripting language.
Scripts offer authors a means to extend HTML documents in highly active
and interactive ways. For example:
-
Scripts may be evaluated as a document loads to modify the contents of
the document dynamically.
-
Scripts may accompany a form to process input as it is entered. Designers
may dynamically fill out parts of a form based on the values of other fields.
They may also ensure that input data conforms to predetermined ranges of
values, that fields are mutually consistent, etc.
-
Scripts may be triggered by events that affect the document, such as loading,
unloading, element focus, mouse movement, etc.
-
Scripts may be linked to form controls (e.g., buttons) to produce graphical
user interface elements (HTML 4.0 draft).
18.1.1 Action occurring away
from user focus
Issue: "Intrinsic events" are events generated
by the elements on an HTML page that can be used to trigger scripts that
accompany a page. These scripts are often used to cause action away from
the user focus. Where the user's focus is limited because they are
accessing the page aurally or only accessing a portion of the page (via
a PDA or screen magnification), these events may go unnoticed. Intrinsic
events are: onfocus, onblur, onchange, onclick, ondblclick, onmousedown,
onmouseup, onmouseover, onmousemove, onmouseout, onkeypress, onkeydown,
onkeyup.
18.1.2 Actions executed during
load of page
Issue: There are two types of scripts: those
that are execute in conjunction with an intrinsic event (just discussed)
and those executed during loading or immediately after the page is loaded.
This includes audio greetings that are played upon opening a page. For
this example, if valuable information about how to navigate the site is
exclusively delivered by audio, people who are unable to hear the greeting
will miss out on the instructions.
18.1.3 Automatic update of page ("push")
Issue : Where an intrinsic event or an
allotted passage of time causes another page to be loaded or more information
to be displayed, a user who has a limited focus may not realize new information
has been displayed. For example, if they are reading a page of basketball
scores line by line with a screen reader, by the time they have read one
score of one game, the page may have reloaded a different set of scores.
In this case they would hear one score for each team for two different
games. Not all users are able to interact with animations or dynamically
changing pages either because they are not able to position and activate
the mouse quickly enough, or do not have the visual information to realize
that the page is changing.
18.1.4 Summary of issues
-
Where the user's focus is limited because they are accessing the page aurally
or only accessing a portion of the page (via a PDA or screen magnification),
events occurring away from the center of the user's focus may go unnoticed.
-
Actions executed during loading or immediately after the page is loaded
may go unnoticed.
-
Where an intrinsic event or an allotted passage of time causes another
page to be loaded or more information to be displayed, a user with a limited
focus may not realize new information has been displayed.
-
Not all users are able to interact with animations or dynamically changing
pages either because they are not quick enough, do not have the visual
information to realize that the page is changing, or do not have the agility
to precisely select a moving image.
Elements affected: almost every element generates at least
one of the intrinsic events
Recommendations for page authors
-
[Required]
Provide a <NOSCRIPT> option for all scripts.
For example:
<SCRIPT type="text/tcl">
...some Tcl script to show a billboard of sports scores...
</SCRIPT>
<NOSCRIPT>
<P> To access today's scores <A href="scores.html">visit
our text-only version.</A>
</NOSCRIPT>
-
[Required]
Provide a mechanism for the user
to freeze any moving or blinking text.
-
More exploration is needed in this area. Please stay tuned.
Recommendations for user agent (browser) designers
-
Provide the
ability to pause "pushes" until the user is ready for them.
-
Provide information
in the status line to let users know that the page is updating or changing.
-
Provide the
ability to break out the text of an animation, banner or etc. and present
it as static text.
19. [Place holder for "SGML reference information for HTML"]
20. [Place holder for "SGML Declaration of HTML 4.0"]
21. [Place holder for "Document Type Definition']
22. [Place holder for "Transitional Document Type Definition']
23. [Place holder for "Frameset Document Type Definition"]
24. [Place holder for "Character entity references in HTML 4.0"]
25. Good Web Site Design Practices
Now that each individual page is accessible, there are few things to
consider about your site as a whole.
-
Page layout is consistent but pages or areas do not look identical.
For example, navigation bars should be located in the same place on
every page.
-
A clear, consistent navigation structure is used.
You should always be able to easily navigate to all documents which
immediately relate, but you should also always be able to get any other
document in the infrastructure with a minimum of fuss. Always provide access
to the original table of contents, or its equivalent. This is especially
important when others create links to documents in your site that are not
necessarily main entry points. This will prevent readers from finding
themselves in the middle of what is obviously a larger document, but without
any means of finding additional information.
-
Navigation bars provide easy access to the navigation structure.
Graphical aids are useful for some persons with learning or intellectual
disabilities. The button bar can be individual .GIF files or an image
map. BUT don't forget to provide alternatives for users who cannot view
graphics. It is helpful to keep the same buttons and the same location
on every page.
-
Instructions are provided to describe the general layout of the site,
the access features used, and how to use them.
For example, if you use D-links describe what information the user
can expect to find when following D-links.
-
A site map is available.
People who have difficulty visualizing the structure of information
can be helped by a site map, a visualization of the structure of the site.
In the future, perhaps user agents will update the view of the site map
with the path of navigation and the location of the current page.
-
Different types of searches are available for different skill levels
and preferences.
Most search facilities require the user to enter keywords for search
terms. Users with spelling disabilities and foreign users will have a difficult
time finding what they need as long as perfect spellings are required.
Search engines could include a spell checker, offering best guess alternatives
or offer different types of searches, for example: query-by-example or
similarity searches.
-
Nothing within the site prevents keyboard operation.
-
Elements outside of the HTML 4.0 specification (such as <BLINK>
and <MARQUEE>) are not used
-
Use a design tool that supports access features (and does not remove
access when you close, or reopen your page using the tool)
-
Test the site with AT LEAST:
-
a text only browser (such as Lynx)
-
a self-voicing browser (such as PWWebspeak)
-
Multiple graphic browsers, with:
-
sounds and graphics loaded,
-
graphics not loaded,
-
sounds not loaded,
-
no mouse
Appendices
A. Design Notes
Alt-text Tips and Tricks
-
Keep the wording simple.
-
Sometimes it is easier to describe what the function of the graphic
is rather than what it is or looks like.
-
Using the height & width attributes for images may cause the alt-text
to wrap, which often makes it unreadable by everyone but Lynx users.
By decreasing the size of the font, the alt-text can be made to fit in
the specified region.
-
Include periods at the end of alt-text of images, especially those used
as links. Periods cause screen readers to pause and will give an indication
of where the alt-text ends and the rest of the text begins. It also ensures
that several links in a row will not be strung together into a single link.
-
Graphical lines can be used to provide extra cues for changes in context,
in comparison with the<HR> element. For example, the alt-text
for a graphical line might be 'Section 2: today's weather."
-
For critical bullets, use numbers or letters as the alt-text so that
they are pronounced.
-
One of the first items a user encounters on the site should be a description
of what protocol is being used. For example, make it clear that images
that have spaces for alt-text or not alt-text at all are not required to
grasp the content of the page.
-
AT&T has created a reference area for creating alt-text available at
http://www.att.com/style/alttext.html
Methods to create alternate pages
-
"By hand"
Sometimes, a site may only need to create text-only pages for layouts
that can not be made accessible. This may involve only a couple of pages.
-
Database-based pages:
Create a database-based server that generates HTML pages on demand
when the user asks for them. In this manner, pages can be constructed "on
the fly" either with or without graphics. An example of this is the the
CommerceNet server.
-
Filters
This approach is similar to Database-based pages, but involves
the use of a filter/translator that would exist on the server as a common
gateway interface (cgi). Pages would be constructed using alt-text and
alternate text pages where needed and, at the direction of the user, be
translated into either graphic or pure text pages on the fly. This method
has disadvantages however. Since all pages must be processed on the fly
(as with the database method), there may be a decrement in performance
unless the filter program is used off-line to create the text versions
of the pages in advance. Secondly, this method would only work for pages
on the server with the AltPage cgi. Whenever references were made to other
pages on other servers, the filter would not work. Image maps on other
servers would be a particular problem unless client-side image maps were
used. Finally, such a filter would create text versions of pages, but since
it would do so by formula, the pages may not be laid out very well or be
very easy to interpret. Building access into the page or providing alternate
pages which are laid out to make sense in text form (and to provide a text
alternative to any Image Maps) as with 1 (By hand) would be much
more effective.
-
Style sheets
References
-
HTML 4.0 draft Available: http://www.w3.org/TR/WD-html40/cover.html
-
World Wide Web browser access recommendations - Jon Gunderson. Available:
http://www.staff.uiuc.edu/~jongund/access-browsers.html
Designing Accessible HTML Pages -- guidelines and overview documents
-
Accessible Design
for Users with Disabilities. -- Sun Microsystems
-
The
Accessible Web: Web Access Through Adaptive Technology -- Kevin Nguyen,
University of Toronto
-
ACT Centre Accessible
Web Design
-
All
Things Web
-
ALT text recommendations,
and notes on viewing situation -- A.J. Flavell, University of Glasgow
-
Alternative
Access to the World Wide Web -- University of Toronto
-
Any Browser Table Format
-- Department of MIssions, Abilene Christian University
-
Best Viewed
With Any Browser -- Accessible Site Design
-
Compatibility & Accessibility
-- Towards the creation of an accessible, truly World-wide Web -- All Things
Web
-
Composing Good HTML -- James
"Eric" Tilton.
-
Design Considerations:
Readers with Visual Impairments -- Arthur R. Murphy
-
Designing Access to WWW Pages
- Alliance for Technology Access.
-
Designing
HTML Tables to Work with HTML 2.0 Browsers -- Stanton McCandlish
-
DO-IT HTML
Guidelines -- University of Washington
-
Experiences Implementing
Web Accessibility Guidelines in IBM -- Phill Jenkins
-
For Web Page Designers
-- Microsoft
-
GSA HTML Accessibility Guidelines
- Paul Fontaine
-
Guide to Writing
Accessible HTML -- University of Toronto
-
Guidelines on
Universal Web-Site Accessibility -- Treasury Board Internet Working
Group on Internet Presentation, Style and Accessibility
-
Hints for designing
accessible Websites -- Royal National Institute for the Blind
-
IBM
Web Design Guidelines
-
Increasing
Access to World Wide Web Sites for Blind and Visually Impaired Computer
Users -- Dena Shumila, Jan Richards
-
InfoUse
Web Accessibility Guidelines
-
LEVELLING
THE ROAD AHEAD: GUIDELINES FOR THE CREATION OF WWW PAGES ACCESSIBLE
TO BLIND AND VISUALLY HANDICAPPED USERS, Judith M. Dixon, Ph.D., Consumer
Relations Officer, National Library Service for the Blind and Physically
Handicapped
-
The Lynx Manifesto
-- Dehanced for Lynx
-
Making Your Site
Speech Friendly -- Cathy Anne Murtha, Web Design and Access Specialist,
Magical Mist Creations
-
NCSA Mosaic Access Page
-
Nimble
Document Navigation Using Alternative Access Tools -- Jutta Treviranus,
University of Toronto
-
On-Line Examples of
HTML Accessibility - Chuck Le Tourneau
-
Tables on non-table
browsers -- A.J. Flavell, Glasgow University
-
Unified
HTML Accessibility Guidelines -- Previous version of this document
-
Universal
Accessibility -- Government of Canada Internet Guide
-
Universal
Design of WWW Pages -- a DO-IT (University of Washington) Brochure
-
Universal Information
Access on the WWW (COCA)
-
"Universal Specifications"
Accessibility Standards for Web Design -- New South Wales Attorney
General's Department
-
Usability of Information
and the WWW -- UCLA Disabilities and Computing Program
-
Web
Accessibility Guidelines -- IBM
-
World
Wide Web Access: Disability Discrimination Act Advisory Notes -- Australia