Web Accessibility Policy: Removing Barriers Through Universal Design
Keep layout simple.
Visually impaired users surf the Web using programs called "screen readers," which read the text that appears on the screen, starting at the left and proceeding to the right. Because screen readers do not actually parse the HTML code that structures pages, they do not correctly read tables; a screen reader will read the entire first line, including the first line of the right column, and then proceed to read the entire second line.
Providing the [Text-Only Version] link at the top left of a page that uses a complex table for layout is an adequate solution to this problem, but should be used sparingly.
Use link text sufficient to stand alone.
Users of screen readers may choose to read a page in one of two ways: either reading all of the text on a page or reading only the link text. Since the latter method is often more efficient, linked text should be as descriptive as possible. Avoid using "Click here for..." in link text.
ALWAYS use the ALT attribute within the <IMG> tag.
Users of screen readers (and even some users who just have slower connections to the Net) generally do not set their browsers to display images, since screen readers cannot read text on images, only ALT text.
For bullets (like a ball), use ALT="*"
For photos, use ALT="", then use the LONGDESC attribute, which is not yet supported by all browsers, but is included in HTML 4.0, to describe the image. You may use color words (e.g., blonde boy wearing red shirt) to describe a graphic, since users who simply choose to browse with their images off can visualize color, but keep in mind that many blind users have no concept of color, so such descriptions may be inadequate. Also, be aware that ALT text that is larger than the dimensions of the image will not appear on the page, which is why LONGDESC is handy; it allows users to obtain more information about the image if desired.
- When using an image as a hyperlink, be sure to use ALT text (see #2 above).
Do not use menus that rely on proprietary technologies.
Avoid using frames.
Frames are particularly problematic for the visually impaired, but also add an extra, unnecessary step in the process of information retrieval for users of text-only browsers, such as Lynx. Official pages make use of tables, rather than frames, to provide a "sidebar menu." (For examples, see the Course Catalogs or many Department Web sites.)
Do not use Flash®!
Flash® content ceases to exist for both the visually impaired and users of text browsers. Individual Flash presentations are fine, so long as you provide the exact same content in HTML form. But why do double the work? Read more about why Flash is bad 99% of the time.
Last modified: Feb 24, 2003, 10:19 EST