Volume II Number 4, December 1995

Leveling The Road Ahead: Guidelines For The Creation Of WWW Pages Accessible To Blind and Visually Handicapped Users

Judith M. Dixon, Ph.D.
National Library Service for the Blind and Physically Handicapped

Traditionally, it has been the role of the librarian to locate, select, organize, and disseminate information resources. With the advent of online services, this role is now being extended to include providing information about electronic resources in addition to those in print.

For blind and visually handicapped computer users, the availability of electronic information has presented an even greater opportunity than it has for those who are able to read printed material. Prior to this, only a very limited amount of reading material had been available in an accessible format. In fact, texts, such as large reference works, have never been accessible to visually impaired users. For this reason, blind people are finding the burgeoning online services of numerous public and specialized libraries to be of great interest. Librarians should expect a growing number of people who have heretofore not been part of their library's patron population to avail themselves of the library's online offerings.

The person whose vision is not good enough to allow the reading of a standard computer screen can gain access to a computer system via refreshable braille display, synthetic speech, or large print. If a braille display or speech synthesizer is used, accompanying screen-reading software is also required. Numerous software and hardware options are available for large-print access. For this discussion, the focus will be on issues affecting blind persons who use speech or braille access to a computer. Generally, access issues for large-print users are less complex, and very little, if any, accommodation is required to meet their needs.

With the expansion of the Internet, blind and visually impaired people have been able to directly access a wide variety of information from thousands of online resources. However, with the increasing popularity of the World Wide Web (WWW), unique and sometimes insurmountable obstacles have arisen that, more and more often, are barring this newly acquired access. The World Wide Web (WWW)

The power and flexibility of the World Wide Web lie in its ability to present information in multiple formats (text, audio, video, graphic, etc.). However, the features that provide power and elegance for some users present barriers to others. For example, services that depend solely on graphic images are completely inaccessible to blind users. Careful design and coding of information can alleviate many of these access barriers.

For blind users, some inroads have been made into the use of graphically based access methods, but the current access still permits only a rather cumbersome and restrictive use of graphics browsers like Mosaic and Netscape. A far more straightforward access opportunity is afforded to blind users by text-based browsers such as Lynx. Since actually "viewing" a graphic element is not usually an option for most blind people, the only possible advantages of using a graphical WWW browser are the instant availability of audio playback, an occasional opportunity to move through an inaccessible image that would halt a text-based browser in its tracks, and the possibility of seeking additional information about a graphic image from a sighted person.

It is not just blind and visually handicapped computer users who may have a need for access options. It is essential to remember the wide range of users you are designing for when creating WWW pages at a library. Library patrons who can connect to the WWW typically range from those with high-speed connections, to those with lower-speed modem connections, and even those with no more than text-based telnet access to the Web. Although it may not always be practical to design for those users with the most limited access, it is still a good idea to remember that these users exist and acknowledge them through warning messages or by creating alternate paths.

A WWW document does not need to be limited only to text to be accessible. There are a number of strategies that can be used to allow inclusion of graphics while still maintaining accessibility. Following these simple guidelines for designing and coding accessible WWW documents can make your documents available and more usable to all. It is important to note that implementing these guidelines does not compromise the aesthetics or functionality of the service.

HTML (Hypertext Markup Language)

HTML is the encoding method used for documents or "pages" on the World Wide Web. Within the HTML language, the designer has the ability to create hypertext references to other HTML pages and resources, both locally and elsewhere on the Internet. These resources can be images, motion videos, and sounds in addition to text files. For librarians establishing Web sites, it is important to know how Web documents are structured and how to apply proper design and layout principles to ensure the desired result.

HTML documents are written in plain ASCII text and can be created using any text editor. Web documents are coded, or "marked-up," with tags resembling those produced by some word-processing programs. These tags serve to structure the page by designating heading sizes, paragraph breaks, lists of items, quoted text, and strong or emphasized words, to name a few.

To view a document on the Web, client software called a "browser" is used -- the most commercially popular browsers being designed for graphical environments such as Microsoft Windows, Macintosh, and OS/2. The recent growth of graphical browsers now gives WWW users a variety of choices for viewing Web pages. Although Mosaic and Netscape may be the current browsers of choice for the well-equipped sighted person, many users still connect to the Web with text-only browsers such as Lynx (developed by the University of Kansas). Some of the reasons people use a text-based browser include:

Designers of WWW pages will not have ultimate control over the appearance of their creations. Each Web browser interprets the HTML codes in a slightly different way with variations in spacing, bullet styles, and general adherence to the current HTML standard (version 2.0). The actual font size and type will be under the control of each user and will be further dependent on the capabilities of the WWW browser in use. Therefore, it is important to test each HTML document on a wide variety of browsers prior to placing the document in a production environment.

Page Layout

To enhance accessibility, keep layout simple. Avoid side-by-side presentation. It is possible to simulate a columnar text format within

 (preformat) HTML tags.  Unless otherwise
instructed to do so, screen-reading software for speech
synthesizers and braille displays presents information one entire
line at a time reading across.  Therefore, columnar information
can be very confusing when encountered unexpectedly.
Hypertext Links

When encoding hypertext links within a WWW page, it is helpful to include enough words in the link so that it could stand alone. Users of speech synthesizers or braille displays can choose to read Web pages in two ways: 1) reading all of the text on the page, including the hypertext links; or, 2) reading only the link text. Since the latter is often more efficient, it is helpful when the link text can stand on its own. If a visually impaired user encounters a page where every link reads "click here," "click here," "click here," the page will be somewhat difficult to use. Users of screen-reading software can quickly review highlighted text, so the more descriptive the link, the better.

Inline Images

An inline image is a graphic element that appears along with the text on a Web page. These are encoded in HTML using the <img src=""> tag. For accessible pages, always include an ALT= attribute within the <img src=""> tag for each inline image provided on the page. This tag provides an opportunity to present textual identification or a description of the image for users with text-only browsers, or for those who choose not to load inline images due to performance issues.

The HTML code for such a reference would look like this:

<IMG SRC="http://lcweb.loc.gov/exhibits/G.Address/intro.gif" ALT="Image of Gettysburg Address exhibit poster, featuring a portrait of Abraham Lincoln">

This ALT (alternate text) attribute is an alternative to the graphics and will be displayed in text-only environments. The ALT text can contain entities, e.g., for accented characters or special symbols, but it can't contain markup.

For simple images, such as icons performing the function of bullets, use simple ALT attributes. Using a long text description, e.g., ALT="This is a little blue ball," clutters the screen and doesn't provide useful information. To simplify things, it is advisable to use bulleted lists (the

code in HTML) or use simple elements to indicate bullets like the asterisk or small letter "o." These are good alternative text choices in the <img src...=""> code, but remember to always include one space after the character you choose (e.g., ALT="* " or ALT="o ").

Using Images as Hypertext Links

If the person attempting to access an image file is using a text-based browser or has graphics turned off in other browsers, the link will be completely lost. A separate "text" file should be made available giving a description and/or a transcript of the image.

An example of such a presentation would be:
Image of the "Nicolay Draft" of the Gettysburg Address. Page 2. 
Transcript of the "Nicolay Draft" of the Gettysburg Address

In general, it is preferable to provide graphic and text options on the same page rather than offer a separate "text-only" page. Even blind users may sometimes want to pull up a picture to show someone, or to have someone describe it in more detail.

Image Maps (ISMAP)

An image map is a graphic that has been mapped to allow different areas of the image to represent hypertext links to other documents (selectable via a mouse). The ISMAP attribute is used within the <img src...=""> tag to denote an image as an image map. Because image maps exclude users with text-based browsers, you must provide an alternate means for selecting those items directly above or below the image map, as well as instructions for the user.

Graphically Based File Formats

Graphically based file formats should be used only as alternatives to ASCII files. Some file formats, such as Portable Document Format (PDF) from Adobe Inc., are strictly graphic in nature and are, therefore, inaccessible to users operating in a text mode or to those who do not have an appropriate viewer for the format.

If documents must be provided in a specialized format, provide the equivalent text file in HTML or plain text format. Some Web sites are introducing special data structures and viewers to differentiate themselves or provide special functions not available with the standard tools. The only way for these custom data and views to be accessible is if the access is built directly into the viewer. Standard access tools do not generally work with special viewers.


The use of forms will restrict only a very small number of users. The most prevalently used text-based browser is forms-capable and can be easily used by those individuals accessing the WWW with speech or braille devices. However, there are some text-based browsers (such as Doslynx) that do not support forms, and such browsers must be used by those with certain kinds of network connections. To accommodate such access methods, it is recommended that an optional e-mail address be provided to allow the individual to submit the requested information by e-mail.

The Future of HTM

L It is anticipated that future versions of HTML will include additional elements that will be beneficial to blind and visually impaired computer users. More opportunities for descriptive text, special table handling, and special treatment for math and science notation are at least part of proposed versions. Conclusion

The precise degree to which a particular WWW site or page is accessible to blind users depends, in large part, on the knowledge and awareness of the Web page designers. Many excellent pages have already been designed so that the content is accessible in a variety of ways, taking into account those accessing the page with a text-based browser while still accommodating those with a desire for more visually stimulating graphical presentations.

In general, to create WWW documents that will be accessible to people with visual disabilities, you need to either avoid using some features and data types or provide alternative methods for carrying out the functions or accessing the information provided through the inaccessible functions. In the future, alternative access methods for standard features may be built directly into WWW browsers, as well as the standard data storage and transmission formats, making it unnecessary to avoid certain features or build redundant mechanisms into your HTML documents. Until these alternative access features and standards are developed, however, care must be taken in the design of HTML pages if they are to be accessible to users with visual impairments.

There are a wide variety of ways to construct a WWW document, and there are many style manuals now available that offer assistance in creating pages that are consistent and easy to use. It is important that each library develop its own standards based on local needs and preferences. Some design considerations presented here, however, are not usually included in most style manuals and should be kept in mind when developing local standards to ensure real accessibility for the entire population.

For Further Information

For a more detailed presentation of these guidelines, you should consult:

"HTML Guidelines" at http://www.trace.wisc.edu/HTMLgide/


"Writing Accessible HTML Code" at http://www.gsa.gov/coca/WWWcode.htm

Dixon, J. M. (1995). Leveling the road ahead: Guidelines for the creation of WWW pages accessible to the blind and visually handicapped users. Information Technology and Disabilities E-Journal, 2(4).