Internal USGS Access Only

Summary of Priority-2 WAI Guidelines

Some of these categories are the same from those in Priority 1, the details will differ.

Don't rely on color alone

Ensure that foreground and background color combinations provide sufficient contrast when viewed by someone having color deficits or when viewed on a black and white screen. Be careful when refering two items of a specific color on the page; ie. All of the red items are ...

Use markup and style sheets and do so properly

Use valid html or xml. Avoid using images to present text (commonly done in navigation bars). Correctly identify headers: H1, H2 etc., lists: OL, UL, DL, quotations: Q and BLOCKQUOTE. Don't use quotation for indenting. Use style sheets to control layout and presentation. Use relative rather than absolute units in style sheet property values. Use MathML to mark up mathematical equations; Links to MathML software.

Create tables that transform gracefully

Do not use tables for layout unless the table makes sense when linearized. If a table is used for layout, do not use any structural markup for the purpose of visual formatting; For example, do not use the TH element to cause the content of a (non-table header) cell to be displayed centered and in bold.

Ensure that pages featuring new technologies transform gracefully

If applets are used to provide content or navigation (not purely decorative), use triggers for applets that are device independent or specify both mouse and keyboard triggers for applets. If you use frame, use NOFRAMES at the end of each frameset.

Ensure user control of time-sensitive content changes

Avoid causing content to blink (i.e., change presentation at a regular rate, such as turning on and off). Do not use moving, blinking, scrolling, auto-updating objects unless you provide a way for them to be paused or stopped. Do not create periodically auto-refreshing pages. Do not use markup to redirect pages automatically. Instead, configure the server to perform redirects. The BLINK and MARQUEE elements are not defined in any W3C HTML specification and should not be used.

Ensure direct accessibility of embedded user interfaces

Create keyboard shortcuts for forms.

Design for device-independence

Provide client-side image maps instead of server-side image maps. Scripts should specify logical event handlers rather than device-dependent event handlers.

Use interim solutions

Do not cause pop-ups or other windows to appear and do not change the current window without informing the user. Keep form labels next to or immediately above form elements to which they refer.

Use W3C technologies and guidelines

Use W3C technologies when they are available and appropriate for a task and use the latest versions when supported. Native formats should be used only as alternatives to html, not as substitutes, ie: PDF, Postscript, Shockwave, etc. Do not use deprecated HTML such as the FONT tag. Avoid requiring the use of plug-ins which do not provide accessibility features.
    USGS ruling on PDF: Files which are generated according to PDF accessibility guidelines are acceptable. Generally speaking this requires more effort than simply converting existing documents to PDF. Both USGS publications guidelines and Jacob Neilsen's Web usability site suggest Gateway Pages for PDF: Even accessibility features enabled, PDF is not especially Web friendly. Mark Bonito's PDF accessibility suggestions.

Provide context and orientation

If you use frames, describe the purpose of frames and how frames relate to each other if it is not obvious by frame titles alone. Divide large blocks of information into more manageable groups where natural and appropriate. Ex: Use OPTGROUP in forms to group OPTION elements inside a SELECT; group form controls with FIELDSET and LEGEND; use nested lists where appropriate; use headings to structure documents, etc. In forms use LABEL and its "FOR" attribute.

Provide clear and consistent navigation mechanisms

Link descriptive phrases. Avoid "click here" (Some speech-enabled browsers provide the option to read only the text that is linked). Consider "TITLE" attribute to clarify the target of a link. Provide metadata to add semantic information to pages and sites. Provide information about the general layout of a site (e.g., a site map or table of contents). Use navigation mechanisms in a consistent manner.

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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_2.html     Last modified: Wed Aug 13 15:19:22 EDT 2003