| Standards |
| Support Web Standards |
- Validate resources to W3C
specificiations
- Avoid deprecated features of W3C specifications to insure interoperability
with legacy, current and future user agents
- Do not use proprietary markup that is not part of W3C specifications
to insure interoperability with legacy, current and future user agents
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| Styling |
| Liquid Design for Content Reflow |
- Content adjusts to the font sizes and typefaces needed by people with
visual impairments
- Content adjusts to the screen resolution and pixel of density of
graphical displays thereby allowing all users to scale content to the size
of the graphical display they are using
- Content adjusts to changes in width of the graphical window, minimizing
the need for horizontal scrolling
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| Layout |
- When content is linearized by ignoring table markup and/or CSS positioning
information it must make sense. This is important for people using
portable devices and people with visual impairments who have disabled
styling and tables or are using a speech synthesizer
- Use stylesheets to control positioning and layout as much as possible
to allow people to restyle content and make content compatible with
portable web browsing devices
- When using tables for layout, use simple table layouts and only include
table cells for major blocks of content. Use CSS for positioning and
styling within table cells
- Avoid embedding tables since it often leads to content not linearizing
well
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| Color |
- Color must not be the only way to convey information (i.e. "press
the blue button" ), since many people cannot distinguish different colors
- Users with visual impairments can adjust foreground and background
colors of text content to improve readability
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| Fonts |
- Do not use images to stylize text since users can not restyle images
to meet their needs
- Use CSS to stylize fonts for interoperability
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| Navigation and Orientation |
| Unique Titles |
- Each page needs a unique title so users can maintain their orientation
within a website
- Use the
title and h1 elements to uniquely
title pages. The title element should contain both the
website name and sub-page information. The h1 element
should only contain the sub-page information
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| Headings |
- Users with visual impairments and physical disabilities can navigate
to main topics of a web resource
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| Menus and Navigation Bars |
- Users with visual impairments and physical disabilities can skip
over repetitive navigation links
- Users with visual impairments and physical disabilities can move
to navigation bars
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| Forms |
- Speech browsers can read the labels of form controls when the control
receives user focus
- Users with visual impairments can receive information about the
label for a form control
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| Language |
- Speech browsers automatically change languages, critical for web
resources that contain two or more languages (e.g. foreign language
courses)
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| Tabular Data Tables |
- Speech browsers automatically announce changes in data cell header
information as a user navigates the content of table cells
- Users can access text summaries of the table data. Summaries are important
for large tables where patterns that can be detected visually cannot be discerned
when using a speech reader or a smaller,
enlarged portion of the table (e.g. handheld device)
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| Lists |
- Users with visual impairments can navigate the items in a list of
information
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| Links |
- Link text should clearly indicate the target of a link
- Speech users can listen to the link text to decide whether to follow
the link
- Server side and client side image maps need redundant text links
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| Accesskeys |
- A limited number of consistently used accesskeys on a website
provide keyboard shortcuts to the main navigation bar, main content
and search feature
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| Frames |
- Frames should be avoided since changes in frames can be difficult
to detect with assistive technologies
- Frames need a title that clearly defines the function of
the frame in a frameset
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| Automation |
| Scripting |
- Do not automatically open content in new windows since this destroys
the history of the user's browsing experience
- Do not use the
onChange event handler in combination with the SELECT
element since this function has poor keyboard support for reviewing
and selecting options in the select box
- Provide a text description of the operation of dynamic interface
elements to inform the user about functionalities supplied by the
scripting
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| Keyboard |
- Operation of automation or scripting functions can be done through
the keyboard alone
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| Objects and Applets |
- Plug-ins and applets should not be used when functionality can be provided
through HTML or other accessibility techniques
- If audio or video content is embedded, provide an option to view the audio
and/or video in an external media player
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| Animations (Flicker) |
- Do not cause content or background to flicker or blink as this
may cause seizures in users with photosensitive epilepsy
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| Timed Responses |
- Time response sensitive resources must give the user an alert and
sufficient time to respond. An option to indicate more time is required
- In systems that require user authentication, users can configure
the system to provide them with the extra time they need to respond
to timed operations
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| Text Descriptions |
| Text Equivalents for Images, Pictures, Charts and Diagrams
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- People with visual impairments and blindness cannot use images
and therefore need text descriptions to understand the content
- Technologies like speech browsers and low resolution graphical/text devices cannot render
graphics but can communicate the text equivalent instead
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| Text Equivalents for Audio |
- People with hearing impairments cannot hear speech clearly or at
all and need a text transcript of audio or synchronized captions for
the audio portion of a video
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