Internal USGS Access Only

Summary of WAI Priority-1 Guidelines

Where there are differences with Section 508 Web requirements, these are noted in square brackets.

Provide equivalent alternatives to auditory and visual content

Be sure that all information is accessible and that navigation aids function without graphics. Provide a text equivalent for every non-text element using "ALT", and if appropriate "LONGDESC". Images that are purely decorative should have an empty ALT tag.(Hint: View pages in lynx to see if the ALT text is helpful and formatted correctly.) If you must use a server-side image map, provide alternate links. Provide equivalent alternatives to auditory and visual content: Transcripts of purely audio information are OK, but movies must have captioning.

Don't rely on color alone

Ensure that all information conveyed with color is also available without color, for example from context or markup.. Tools: A source for "Colors for the Color Blind". Vischeck allows you to see what your web pages would look like to color blind individuals.

Clarify natural language usage

Clearly identify changes in the "spoken" language of a document's text and any text equivalents (e.g., captions). For example, use the "LANG" attribute to identify quotes or sections in a different language.
[not a 508 requirement]

Create tables that transform gracefully

Ensure that tables have necessary markup. For simple data tables, identify row and column headers with TH, use TD for data cells. For data tables that have two or more logical levels of row or column headers, use markup to associate data cells and header cells. For example, use the "HEADERS" and "ID" attributes, to describe more complex relationships among data.

Ensure that pages featuring new technologies transform gracefully

Ensure that pages are accessible even when newer technologies are not supported or are turned off. Pages must be useful if style sheets or scripting languages are unavailable to the browser. Provide alternative text (ALT or NOSCRIPT) if appropriate. Ensure that equivalents for dynamic content are updated when the dynamic content changes.

Ensure user control of time-sensitive content changes

Avoid causing the screen to flicker. Note: People with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second as well as quick changes from dark to light (like strobe lights).
[508 requirement forbids flicker frequency greater than 2 Hz and lower than 55 Hz. When a timed response is required, the user shall be alerted and given sufficient time to indicate more time is required.]

Ensure direct accessibility of embedded user interfaces

When an embedded object has its "own interface", the interface -- like the interface to the browser itself -- must be accessible. (PDF and Shockwave are examples)
[plug-ins may be used if a link is provided to the plug-in, and the plug-in itself meets all section 508 software interface requirements, see §1194.21]

Design for device-independence

Provide client-side image maps instead of server-side image maps or provide redundant text links.

Use W3C technologies and guidelines

If, after best efforts, you cannot create an accessible page, provide a link to an alternative page that uses W3C technologies, is accessible, has equivalent information (or functionality), and is updated as often as the inaccessible (original) page.
[not a 508 requirement]

Provide context and orientation

If you use frames, title each frame to facilitate frame identification and navigation.

Ensure that documents are clear and simple

Use the clearest and simplest language appropriate for a site's content.
[not a 508 requirement]

Section 508 Requirements Which are Not WAI Priority-1

Accessible forms

[§1194.22(n) When electronic forms are designed to be completed on-line, 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.]

Make it possible to skip repetitive links

[§1194.22(o) A method shall be provided that permits users to skip repetitive navigation links.]
A TABINDEX="1" attribute should be assigned to the first link after any top of the page navigation.

Checklist of Checkpoints for Web Content Accessibility Guidelines 1.0

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"Mastering a Web Site" online course Created and maintained by Lorna Schmid and David Boldt. http://water.usgs.gov/usgs/training/webmaster/accessibility_guidelines_1.html     Last modified: Wed Nov 12 17:16:15 EST 2003