D-tags discussion

D-tags or "description tags" have been pioneered by WGBH in order to more fully describe a graphic image than an alt-text would. A d-tag is a capital "D" text anchor that appears next to or below an image. Following this "D" link brings up a page with a description of the image. Because d-tag descriptions appear on their own page, they can be as long as an author wants them to be. Therefore, users can receive more information about the physical description of graphic images than alt-text allows.

The following discussions were generated by looking at worse case scenarios. Often, the pages that were viewed as models were totally unrecognizable by the screen readers used. The problems that arose dealt with cluttering of the original image map page, the need to toggle back and forth between d-tag page and image map page, and the extra work needed to maintain the WEB site. We are striving to find a solution which can alleviate problems for users and designers alike.

Send us your suggestions and comments at web-team@trace.wsc.edu.

POSSIBLE STRATEGIES FOR THE USE OF D-TAGS WITH IMAGE MAPS

D-TAG FORMATS

There is currently no best format for a d-tag page. Five possible formats are discussed below.
  1. When the user clicks on a d-tag, they could be presented with the description of the image map, as well as the links from the image map itself. However, there may be links on the original page that are not reachable from the image map and thus cannot be accessed from the d-tag page.

    Only image map links in the d-tag page.

  2. When the user clicks on a d-tag, they could be presented with the description of the image map, links in the image map itself, and all the links on that page that are not included in the image map. In this way, the user who wishes to understand the image map, by reading the description, would have the same access a sighted person would have on the original page. However, this would increase the amount of maintenance needed of the WEB site.

    All links included in the d-tag page.

  3. Another way to increase access would be to present the image map links and all other links on the original page with alt-text, d-tags and text anchors. However, this could give the image map page a cluttered look.

    One page with the alt-text, d-tags and text anchors.

  4. To decrease the amount of maintenance needed at the WEB site, the d-tag page could include only a link which returned the user to the original page. All other links would be accessed from the original page. However, this would mean that the person who wanted a description of the image map would have to make an extra link purely for the purpose of discovering the particulars about the visual properties of the image map.

    Only a return link in the d-tag page.

  5. The d-tags could not appear on the image map page at all. Each time a d-tag could be used, a text version of that page could be presented instead. The explanation of the image map would appear on the text page. The text page would have the same option of having links in it or not. However, you would be creating text pages which would otherwise not be needed.

    Text version instead of d-tag.

PRESERVING THE FEEL OF THE SITE

When d-tags appear on the image map page, there is a need keep the d-tags as unobtrusive as possible.
  1. One suggestion is to use a very small font. However, certain screen readers have problems dealing with rapid font size changes. Therefore the size of the d-tag would have to be large enough to be read by a screen reader. More research will be needed in this area.
  2. Another suggestion, when available, would be to have visually nested links. We are hopeful that in the future it will be possible to include d-tags in the alt-text link. In this case, when you have images turned on, you would be able to see the graphics page without the clutter of the d-tag.
  3. A third suggestion is to maximize the knowledge of the graphical image. This can be done by thoughtfully labeling the alt-text. For example, if the graphic was a man hole cover with a "need to repair" symbol, the alt-text might say, "man hole cover with repair symbol." The graphic would be completely defined in the alt-text and a d-tag would not be needed. In addition, any person who does not have graphics turned on would have a greater knowledge of whether they wanted to follow the link attached to the graphic. However, complicated graphics cannot be dealt with in this manner.

TEXT VERSIONS OF A PAGE OR AN ENTIRE SITE

There are many reasons for choosing to use a text version of a page. One reason for using a text version of a page is the inaccessibility of the original page. The text version gives an accessible alternative. Another reason is due to the inability, in any other acceptable format, to present to a screen reader all the information a sighted person would be able to see at one time. A third reason is to give the ability to rapidly read the text without unwanted graphics. With a variety of needs, problems can arise.
  1. When the site developer creates a text version of a page, would d-tags be included on this page? The problem here is that some people read text pages because of the ability to rapidly read the text without unwanted graphical information, while others read it because of its accessibility. If you put a d-tag on the text page, you would also have to include a symbol, as a place holder for the graphic, in order to allow the persons who are using the text version for accessibility, to know where the graphic appeared on the page. This would mean more clutter for those who only wanted to read the text.

  2. When only part of the site contain text versions, how does the user know if the text page is taking them to another text page or to a graphical page? The designer may wish to keep the continuity of the site by causing the text pages to have much the same feel of the rest of the site. In other words, instead of being purely text, these pages would maintain the symbols, d-tags, and other references to graphical images which appear on the original page. In this way, when the user ends up on a page which is not a text page, a difference will not be felt. However, this means making the page more cluttered for purely text readers and is not truly a text page for those who need it.

  3. Presenting a text version of the entire site is useful to persons using screen readers, text browsers, and any person who feel that they don't want the graphics. This topic, however, needs more investigation.

CONCLUSION

We need to carefully look at the different d-tag scenarios to determine which approaches will provide effective and efficient access while keeping the page easy to maintain and nice looking. In addition, we need to have a better feel of whom would desire the d-tags so that the d-tags could best meet the needs of the users.