Equivalent Text Descriptions - A Proposed Standard
Denis Anson, MS, OTR & Roger O. Smith, Ph.D., OT, FAOTA
Misericordia University & University of Wisconsin, Milwaukee
Abstract
Current web guidelines require that all "non-text elements" have a text equivalent in order to provide equal access for people with disbilities. This seemingly simple requirement turns out to be much more complex on examination. The current HTML standard provides two mechanisms for provision of text equivalents, but no guidance has to which should be used, or how best to provide the text equivalent.
This paper proposes guidelines for the provision of text equivalents to maximize the equality of access to electronic documents for those who are not able to benefit directly from graphical presentations.
Kewords:
Text equivalents, alternative text, web design, accessible design
Introduction
The Web Content Accessibility Guidelines 1.0 (Letourneau & Vanderheiden, 1999) states, as its first rule, that the web designer should: “Provide a text equivalent for every non-text element (e.g., via “alt,” “longdesc,” or in element content)…[Priority 1]” While this seems a straightforward concept, the application has proven to be quite difficult. Most authors are able to identify the non-text elements of a page, but many seem to have difficulty identifying what constitutes a text equivalent. In some cases, when a web page is created by importing a word-processing file, it may not be clear that some of the content is not text.
The fundamental concept of equivalent-text is that a reader who does not have access to a non-text element should still have access to the information of the document (Flavell, 1994). Electronic text has the compelling advantage that it can be delivered, without loss, to a variety of senses and made accessible using various cognitive approaches. Unlike pictures, electronic text can be easily spoken as well as displayed on a screen or printed.
Constructing and Presenting Effective Text Equivalents
Non-text elements are included in documents for a number of different purposes. The text equivalents for each may be different. In designing a text equivalent, it is critical to know the purpose of the element, and its contribution to the document. Some non-text elements convey simple information. Others have much more complex intent.
Document Information
Three types of non-text elements pertain to the document content. These are a) in-line information, b) out-of-flow information, and c) the document meta-information that includes the overall design, layout and format. In-line information is included within the structure of the sentences of the document, and would be spoken immediately by a person reading the document aloud. Out-of-flow information, while important to the overall document, may be processed immediately or at a later time without loss of value. Document meta-information is not essential to understanding the content of the document, but may be useful in placing that information in a larger context.
In-line Non-text Information
Some types of non-text elements are crucial to understanding the meaning of a sentence. Any in-line non-text elements (those that are incorporated into the flow of a sentence) should be accompanied by a text equivalent that contains the words that would be used when reading the sentence aloud. For example, if the document includes the equation 
as created in an equation editor, (and hence, existing as a graphic in the document) the text alternative would be ‘alt=“aye squared plus bee squared equals sea squared”’. Hear this paragraph without alt-text and with alt-text.
One important limitation of many text-to-speech systems is that they do not provide all of the information even for keyboard input. Many Greek letters used in mathematics are simply ignored or are named as their Roman equivalent, changing “α
” to “a.” Similarly, positional information such as superscript and subscripts are not announced. (a2 +b2 =c2 ) Because these are not graphical images, and not even non-text elements, there is neither a mandate nor a standard method to provide text equivalents (even when the information is essential to understanding the document!) One means of repairing omissions after a document has been authored is to place an invisible graphic (usually a one-pixel, transparent .gif image) in the document flow, and then use the alt-tag for that element to provide the missing information. (Hear this paragraph without alt-text and with alt-text.)
Out-of-flow Non-text Information
Figure 1: Counselor Perception of Their Role in Providing RT and Perception of Their Capacity to Perform These Roles d (Click image for larger view) Image from http://www.resna.org/ ProfResources/ Publications/ Proceedings/2006/ Research/PP/Noll.php (Click for larger view) Some non-text elements provide concentrated presentations of complex information. These require significant mental effort to process, but are not part of the flow of the text in document. These elements may expand on statements made in the flow of the narration, may enhance the understanding of the reader, or may act as the central medium of information. In print, such elements (graphics) often have a caption that allows the reader to analyze or ignore the image for the moment.
For any non-text, out-of-flow element of the page that is intended to provide information about the topic, the author must provide the intended information in a text equivalent. However, there are considerations that control how this is done. When a person who is reading a document with sights and sounds of the page encounters a graph, animation, or other non-text element, s/he is free to skip over the element for future consideration. Webpage design provides a tangible example, but the design issues are much broader than the web and include all media types. (Hear this section read with in-line text equivalent and with notification.)
When traditional alt-text is used in an HTML document, the text equivalent is provided in the flow of the document, and no such choice is available. This approach provides an inherent difference (or so it would seem) for the consumer of alt-text.
Web content guidelines recommend that an “alt-text” be limited to 50 to 70 words, which may not provide adequate space to convey the information of the element to which it is attached. To allow for a more complete text equivalent, the HTML standard specifies a “long description” attribute that allows an arbitrarily long equivalent text to be supplied in a separate document. Because the longdesc is not fully supported, many authors recommend the “d-link,” a letter “D” (upper or lower case) that is a link to the longer description. In combination, the alt-text and longdesc/d-link offer a means of providing text equivalents for supporting information that is equivalent to access by those with full multimedia access.
The proposed approach is to include, for all out-of-flow non-text elements (those that are not embedded into a sentence) an alt-text that describes, briefly, the non-text element. The usual rule that says that an alt-text that includes the words “picture,” “graph,” or “image” is probably not effective. We are recommending that the attached alt-text inform the reader that the non-text element is a “graph of the perceived role and capability of vocational counselors,” but not try to provide the information of the graph.
The alt-text description of the purpose of the graph should be immediately followed by a link to a long-description conveying the information of the graph. This long-description would include all of the information of the graph, as well as a summary of the graph. At the end of the long description, a link should be provided that returns the reader to the point of departure from the original document. In a complex document, returning the reader to the location of the non-text element rather than the top of the document is vital to usability.
This strategy allows the reader to receive, in the flow of the document, the fact that additional information is available. At that point, the reader has to option to follow the link to the long-description and receive the information, or to continue with the narrative flow, and return to the non-text information at a later time.
Document/Element Meta Information
The meta-information of a document is information that describes, modifies or contributes to the document rather than to the topic of the document. Some elements may set the context for a document, and others change the look and feel of the document. Some (but not all) users who depend on text equivalents argue that they should have access to all of the information about a document, including descriptions of the decorative elements. Just as information about the visual representation of a document can be beneficial to the reader who cannot see it, information about a non-text element can be useful, for many of the same reasons. However, supplemental information should not interfere with access to the primary information of the document.
Decorative Elements
Commonly called “eye candy” or “ear candy,” decorative elements are included primarily to produce a more pleasant reading experience or for corporate “branding.” Eye candy might include a decorative border or a background color scheme. In electronic documents, these can be static or dynamic. “Ear candy” might include recorded sound effects, musical theme, or other sounds to attract (or distract) the reader.
It has been argued that decorative elements do not contribute to the information of a document, and should be presented with an empty text equivalent (Clark, 2001, 2003; Coombs, 2005; Flavell, 1994; Lynch & Horton, 2002; Willison, 2004). It has been argued, however, that in some cases eye-candy can be useful to the reader by making the document distinct rather than enhancing the document content. A sighted person might assist a friend looking for an article that has a picture of a panda bear in the top right corner. This allows the sighted searcher to quickly scan articles without requiring language processing. In the case of a blind person guiding a sighted person to the document, if no information about the page decoration is available, such cues cannot be provided.
Informational element meta-information
The element meta-information might include a wide range of information. In a description of a photograph where the document information is of an interaction in the foreground (“A man helping a child get a drink of water from a drinking fountain”), the meta-information might include the information that the drinking fountain is near the edge of the Grand Canyon, that it is a sunny day, and that a flock of birds is flying over. None of this is relevant to the surrounding document on intergenerational assistance though the visual context may convey that assistance is needed everywhere.
A “fully accessible” electronic document should include a link to a “document description.” The reader would be able to follow this link to find a description of the appearance or sound of the document. Such a description might include a description of the placement of non-text element and possibly text elements such as headings or tables on the page. In addition, an “i-link” should be included where decorative or informational elements are placed to describe them.
One complex example of element meta-information can be found in the inclusion of institutional or corporate logos as decorative elements in a document. The logo might well have a great deal of symbolism to the company. In such a case, the best text equivalent for a logo might well be the name of the company acting as a link to the corporation’s “About Us” page.
However, because this information is not desired by all readers, and constitutes cognitive noise to some, it should be provided in a way that allows the reader to access it electively. We suggest that authors include an element description that is similar to the document description as a long-description, linked from the long-description of the non-text element.
Summary
The proposed standard for text equivalents recognizes three categories of alt-text: inline, out-of-flow, and meta information.
Key to implementing these three types is that non-text equivalent descriptions should be multi-leveled. Information that is required to interpret a sentence in a document should be provided seamlessly and immediately. The person using an alternative representation should be essentially unaware of the change. Information that is important to the document, but that is not part of the narrative flow should be indicated in the flow, with links to the additional information that can be followed at the reader’s discretion. Authors and publishers should not assume that only one level of description is necessary or that non-text equivalent descriptions are only necessary for the traditional photograph or figure.
Bibliography
- Clark, J. (2001). World Wide Web access and information apartheid. Retrieved Nov. 8, 2005, from http://www.joeclark.org/wwwaccess.html
- Clark, J. (2003). Building Accessible Websites. Indianapolis: New Riders.
- Coombs, N. Good Distance Learning Principles. Retrieved April 25, 2005, from http://easi.cc/media/trans/tncsndl.htm
- Flavell, A. J. (1994, March 2, 2007). Use of ALT texts in IMGs. Retrieved Jan. 8, 2008, from http://htmlhelp.com/feature/art3.htm
- Letourneau, C., & Vanderheiden, G. C. (1999). Web Content Accessibility Guidelines 1.0. Retrieved Jan. 8, 2008, from http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/
- Lynch, P. J., & Horton, S. (2002). Web Style Guide: Basic Design Principles for Creating Web Sites (2nd ed.): Yale University Press.
- Willison, S. (2004). Writing good ALT text. Retrieved Jan. 8, 2008, from http://www.gawds.org/show.php?contentid=28
Acknowledgement
The ACCESS-ed Project is supported in part by the U.S. Department of Education’s office of Post-secondary Education, PR/Award #P33A050090. The opinions contained in this publication are those of the grantee and do not necessarily reflect those of U.S. Department of Education.
Author Contact Information
Denis Anson, MS, OTR
Director of Research and Development
Assistive Technology Research Institute
Misericordia University
Dallas, PA 18612
570-674-6413
danson@misericordia.edu