Basic Web Accessibility Guidelines
Anything that prevents a person from obtaining needed information
makes that content inaccessible.
Accessibility begins with good design. The following ten guidelines
should assist you in creating Web pages which ALL users can access. The
guidelines are based on recommendations from the World
Wide Web Consortium (W3C) and the standards created by the Architectural
and Transportation Barriers Compliance Board (Access Board) as part
of Section
508 of the Rehabilitation Act of 1973.
The guidelines are first presented in a simple list. The list links
to additional information about each guidelines, whose components are
categorized as being either "required" according to
the University World Wide Web Policy, "recommended"
or "coming soon," which means they are currently neither
required nor recommended, but they may soon become so. Check back
frequently, as guidelines will be updated as more information becomes
available.
Many items are followed by
Examples. The examples include instructions
for HTML source code as well as for FrontPage 2000, but other Web page
authoring programs can accomplish the same result in different ways.
Once you've developed your Web pages, test them for accessibility
using a validator such as Bobby
(http://www.cast.org/bobby/). Additional accessibility information is
available on our Resource List
Web page.
|
Number
|
Guideline Description
|
| Guideline 1
|
Create Web pages that are clear
and simple, so they are more easily understood. |
| Guideline 2 |
Logically organize your page and
use HTML to encode meaning rather than appearance -- use HTML
tags for purpose they were created and use style sheets where
appropriate. |
| Guideline 3
|
Provide equivalent alternatives
to auditory and visual content, including images, graphics,
animated graphics, image maps, video clips and audio clips or
sounds, and to any other non-text elements, including applets,
programmatic objects, and scripts. |
| Guideline 4 |
Provide clear and consistent navigation
and links. |
| Guideline 5 |
Use color and background images
judiciously. |
| Guideline 6 |
Create tables that work properly. |
| Guideline 7 |
Don't use moving, blinking, scrolling
or automatically-updating objects, or ensure that these objects
or pages may be paused or stopped. |
| Guideline 8 |
Ensure that forms provide device-independent
access. |
| Guideline 9 |
Avoid using frames.
|
| Guideline 10 |
Additional considerations, including
using "text-only" pages and PDF files. |
- Create Web pages that are clear and simple,
so they are more easily understood.
- REQUIRED: Consistent page layout, recognizable graphics
and easy-to-understand language benefit all users. Use the clearest
and simplest language appropriate for a site's content and audience.
"Every word and phrase should have to fight
for its life.
That means writing 'use' instead of 'utilize' which is
identical in meaning, but has two more syllables."
--Crawford Kilian, "Effective Web Writing," Web
Techniques, Feb 2001
- REQUIRED: Clearly identify places where text or text
equivalents change to a different language to facilitate pronunciation
or interpretation of foreign text. Speech synthesizers and Braille
devices can automatically switch to the new language if appropriate
HTML markup is used.
Example of guideline 1B - using different
languages
- RECOMMENDED: Expand abbreviations and acronyms the
first time they occur to assist with interpretation.
Example:
The UTC (University Technology Committee) recently approved the
University Web Policy.
- RECOMMENDED: To reduce confusion, don't use style sheets
to remove the underlining from hyperlinks and don't underline
text or headings (that aren't hyperlinks). Users have learned
that hyperlinks are underlined.
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- Logically organize your page and use HTML to
encode meaning rather than appearance -- use HTML tags for purpose
they were created and use style sheets where appropriate.
- REQUIRED: Use HTML tags for the purpose they were created.
For example, for headers use header tags <H1><H2>,
etc., rather than font size changes, to note sections and subsections
of your page.
Use style sheets rather than <blockquote></blockquote>
or list tags to create indentation or margins. The <q></q>
tag is used within a paragraph to quote a direct source. The
<blockquote></blockquote> tag is used for a longer
quote, which is "blocked" or indented from each side margin.
Use list tags only to create lists.
Use style sheets, not header tags, to create changes in
font size.
(See next recommendation 2C below for more information on
using style sheets.)
- REQUIRED: Documents must be readable without requiring
associated style sheets. (See next recommendation for more information
on using style sheets.)
Turn off style sheets within your browser to test how your page
will look.
In Netscape:
Edit | Preferences | Advanced
Uncheck "Enable style sheets." Click "OK"
In IE:
Tools | Internet Options | General
Click on "Accessibility" (bottom of page)
Check "Ignore font styles specified on Web pages."
Click "OK" and "OK" again.
- RECOMMENDED: Lists -- to make your lists more accessible,
do the following:
Announce the occurrence of the list and announce the number
of available choices before the list begins.
Label list items numerically.
Label sublist items alphabetically.
Example:
The following list identifies three basic accessibility guidelines.
- Create Web pages that are clear and simple, so they are
more easily understood.
- Logically organize your page and use HTML to encode meaning
rather than appearance.
- Provide equivalent alternatives to auditory and visual
content.
- All <img> tags must include an "alt"
attribute
- Use simple words to describe the function of structural
elements rather than describing the appearance.
- RECOMMENDED: Divide large blocks of information into
more manageable groups where natural and appropriate. Use a "Table
of Contents" at the top of your page (where appropriate)
and provide "Back to Top" links at each section break.
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- Provide equivalent alternatives to auditory
and visual content, including images, graphics, animated graphics,
image maps, video clips and audio clips or sounds, and to any other
non-text elements, including applets, programmatic objects, and scripts.
When considering use of images, audio and video content, first ask
yourself these questions: "What is the purpose of this visual
content? How important is the visual content to the meaning of the
page/site? How can I convey the information presented in the visual
or auditory content for those who aren't able to see, read or hear
it?"
If the visual content provides no clear advantage or meaning, consider
omitting it. The benefit of the content should outweigh the inconvenience
of additional download time. If the content provides a clear advantage,
be sure to make it accessible using the following guidelines.
- REQUIRED: All <IMG> tags must include an "alt"
attribute, which contains a brief, interpretive text description
for users who have images turned off, are using text-browsers
or are using screen-readers.
If no alternative text is provided, then text-browsers and screen
readers will display/read [inline-image] as the description. Don't
use alt=" " because screen readers may say "blank"
instead of saying nothing at all. This may confuse the user. The
"alt" attribute can also be used to provide a small
amount of additional information.
Example:
The "alt" attribute in the following code is describing
a graphic image which simply says, "What's New."
<A HREF="/announce/"><img src="new.gif"
width="30" height="14" ALT="What's New
at APSU"></a>
If you are using Microsoft FrontPage to create or edit your pages,
you will need to explicitly insert the text alternative because
you will not be prompted to do so. Select the image; right-click
on the image and choose the "Picture Properties" option.
Provide the description in the "alternative representations"
text window.
- REQUIRED: Use simple words to describe the function
of graphical elements rather than describing the appearance.
Examples:
Use the word "bullet" to describe an image that
precedes list items
<img src="arrow1.gif" alt="bullet"
width="9" height="9">
Use the words "page divider" or "separator"
to describe an image which separates portions of your page.
Use the words "spacer graphic" to describe images that
provide space or "hold together" your page elements
(e.g. shim.gif).
- REQUIRED: Image maps must include "alt" attributes
for all hyperlinks. Describe the graphic image used for the image
map by providing an "alt" attribute with the <area>
tag or provide a hyperlink for a text html page, which describes
the graphic image map. To assist users who have difficulty with
fine motor movements, design image maps that don't require extremely
precise mouse positioning.
Example of Guideline 3C - including"alt"
attributes for image maps
- REQUIRED: Use client-side image maps instead of server-side
image maps except where the regions cannot be defined with an
available geometric shape.
- REQUIRED: If a server-side image map must be used, provide
"redundant" text links for each active region of the
image map.
- REQUIRED: Provide a hyperlink to a text html page or
provide an audio description of the important information of any
video content. The Office of Disability Services can provide a
list of names of audio describers who are trained to provide a
text description of visual images.
- REQUIRED: For any time-based multimedia presentation
(e.g. a movie), provide a synchronized equivalent. Using
a product such as MAGpie
it is possible to produce a video clip that contains synchronized
captions and descriptive video.
- REQUIRED: When a Web page uses scripting languages to
display content or to create interface elements, the information
provided by the script shall be identified with functional text
that can be read by assistive technology.
- REQUIRED: When a Web page requires that an applet, plug-in
or other application be present on the client system to interpret
page content, the page must provide a link to a plug-in or applet
that will function with assistive technology.
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- Provide clear and consistent navigation and
links.
- REQUIRED: Use descriptive, concise hyperlink names.
Hyperlinks should make sense when they are read one at a time
or out of context. Rewriting the phrase or sentence surrounding
the link is the best way to eliminate confusion. (e.g. Rather
than writing "You can now find APSU news releases online.
Click here.", write "You can now find
APSU news releases online.") Most screen readers will
pull out all of the links of a page, providing users with a way
to navigate quickly. Just imagine a list of links similar to this:
click me
over here
click this
- REQUIRED: Provide a way that permits users to skip repetitive
navigation links.The
following information comes from the W3C:
When links are grouped into logical sets (for example, in a navigation
bar that appears on every page in a site) they should be marked
up as a unit. Navigation bars are usually the first thing someone
encounters on a page. For users with speech synthesizers, this
means having to hear a number of links on every page before reaching
the interesting content of a page. There are several ways to allow
users to bypass groups of links (as users with vision do when
they see the same set on each page):
Include a link that allows users to skip over the set of navigation
links.
Provide a style sheet that allows users to hide the set of navigation
links.
Use the HTML 4.01 MAP element to group links, then identify the
group with the "title" attribute.
In the future, user agents may allow users to skip over elements
such as navigation bars.
Examples of guideline 4B - skipping
navigation links
End of W3C information.
- RECOMMENDED: Provide sufficient space between links
to assist users who have difficulty with fine motor movements.
Providing space around, and separators between, links also makes
it easier for sighted users to differentiate among the links.
The pipe character ( | ) is a good alternative for separating
consecutive links, and most screen readers have adapted to reading
this as a break between navigational links.
Example:
[ Undergraduate Admissions | Graduate Admissions ]
- RECOMMENDED: Avoid using hyperlinked images as the
sole source for navigation. If you use an image, combine it with
text that describes the hyperlink and include a text equivalent.
- RECOMMENDED: Avoid automatically redirecting the user
from one Web page address to another. Every time the user clicks
the "Back" button in the browser menu bar, the browser
returns to a page that bounces the user forward to the same page
on which he is currently located. If you must use an immediate
redirect, provide links to appropriate pages (including www.apsu.edu)
to help the user get out of the "redirect loop."
- RECOMMENDED: Place navigation links and buttons in
a consistent location throughout your site.
- RECOMMENDED: Avoid using pop-up windows or causing
a hyperlink to open in a new browser window, as this can be confusing
to users who can't see that this has happened. If you are going
to open a link within a new browser window, inform the user prior
to the hyperlink.
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- Use color and background images judiciously.
- REQUIRED: Ensure that all information conveyed with
color is understandable if viewed without color or if presented
in an auditory manner.
If color alone is used to convey information, people with certain
visual impairments, people using text-only browsers or those using
screen reading software will have difficulty discerning meaning.
Don't use color as the only way to differentiate choices, demonstrate
emphasis or indicate mandatory fields on a form.
- REQUIRED: Background images must be light enough that
they don’t hinder readability or lessen the contrast between the
text and the background.
- RECOMMENDED: Provide sufficient contrast between background
and text colors, so the text on the page is legible.
Dark letters on a light background are easier to read than light
letters on a dark background. In addition, light letters
won't be legible when printed.
The most common form of colorblindness is red-green, so this combination
is especially troublesome.
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- Create tables that work properly.
- REQUIRED: For Web visitors using screen readers, tables
will be read beginning with the cell at the upper-left-hand corner
of the table. That cell will be read in its entirety, and then
the next cell to the right will be read. Be sure your information
makes sense when read in this order. Otherwise, provide an alternative
equivalent (e.g. providing the information in a non-tabular format).
To get a better understanding of how a screen reader would read
a table, run a piece of paper down the page and read your table
line by line.
- REQUIRED: Use the <TH> tag to identify a header
or title for a table column or row, and use the <TD> tag
to identify data in each table cell that corresponds to the header
or title.
Example of guideline 6B
- using <TH> and <TD> tags
- REQUIRED: For data tables that have two or more logical
views of row or column headers, use markup to associate data cells
and header cells to describe more complex relationships among
data.
Example of guideline 6C
- associating data and header cells
More information from the W3C on using
markup to associate data and header cells.
- RECOMMENDED: If you use an absolute width for your
table, be sure it will fully display on a browser set to 640x480
resolution (try 580 pixels). If your table extends beyond the
browser window, a screen reader may only read to the edge of the
window, ignoring all text beyond the window.
- RECOMMENDED: Provide a summary via the "summary"
attribute within the table tag.
Example:
<TABLE border="0" summary="This is a summary of
the table.">
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- Don't use moving, blinking, scrolling or automatically-updating
objects, or ensure that these objects or pages may be paused or stopped
and/or provide equivalent information in an alternative accessible
format.
Screen readers are unable to read moving text. Some people with cognitive
or visual disabilities are unable to read moving text quickly enough
or at all. Movement can also cause such a distraction that the rest
of the page becomes unreadable.
- REQUIRED: Don't use the <BLINK> or <MARQUEE>
elements.
- REQUIRED: Don't cause the screen to flicker. A flickering
or flashing screen may cause seizures in users with photosensitive
epilepsy. Seizures can be triggered by flickering or flashing
in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity
at 20 flashes per second as well as quick changes from dark to
light (like strobe lights).
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- Ensure that forms provide device-independent
access.
Device-independent access means that the user may interact with the
user agent or document with a preferred input (or output) device,
such as a mouse, keyboard, voice or head wand. If a form control can
only be activated with a mouse or other pointing device, someone who
is using the page without sight, with voice input, or with only a
keyboard will not be able to use the form.
- REQUIRED: When electronic forms are designed to be completed
online, the form shall allow people using assistive technology
to access the information, field elements and functionality required
for completion and submission of the form, including all directions
and cues.
- REQUIRED: Provide a phone number the Web visitor can
call to verbally supply the requested information. An e-mail address
should also be included.
- RECOMMENDED: Preface each form element with a descriptive
name followed by a colon. The Microsoft Active Accessibility (MSAA)
software calls each form element by the word prior to and on the
same line as the form element.
Example:
Name: <INPUT TYPE="text">
- RECOMMENDED: Keep the form element and its description
on the same line in the form.
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- Avoid using frames.
Unless you have a compelling reason to use frames, avoid them altogether.
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- Additional considerations, including using
"text-only" pages and PDF files.
- REQUIRED: A text-only alternative page should be used
only when compliance cannot be accomplished in any other way.
If used, the content of the text-only page must be updated at
the same time as its graphical counterpart.
Work to produce accessible Web pages. Having two versions of the
same page doubles your maintenance time.
- REQUIRED: When providing a PDF (portable document format
by Adobe), test to see whether the file can be read with screen
reading software. If it can't, provide a text file equivalent
either in HTML or text format. Adobe
currently provides an accessibility
tool that you can use to convert a PDF file to an HTML or
text format.
- RECOMMENDED: When providing files for downloading, provide
a non-proprietary file format (.txt) option
- RECOMMENDED: Avoid absolute or fixed font sizes. Use
relational instead (e.g. 1, 2). Users with poor eyesight may need
to adjust font size within browser to see/read your pages, and
absolute font sizes may not adjust. Test your pages with the default
font set to 10, 12 and 14 points to ensure your design is user-friendly
for these font sizes.
- RECOMMENDED: Use a text-only browser such as
the VAX system to
test how your pages will look/read using text only. Using a telnet
utility, log onto discover.apsu.edu. At the prompt, type the
word "lynx." Choose "G" for "Go"
and at the prompt, type in the URL for the page you wish to check.
- RECOMMENDED: Use an accessibility validator such as
Bobby to test your
pages.
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