- From: Charles McCathieNevile <charles@w3.org>
- Date: Tue, 23 Mar 1999 16:43:04 -0500 (EST)
- To: Ehansen7@aol.com
- cc: w3c-wai-gl@w3.org, ehansen@ets.org
my comments CMN: On Tue, 23 Mar 1999 Ehansen7@aol.com wrote: 1. Scope and Limitations {EH: This belongs somewhere early in the document} Adherence to the guidelines cannot guarantee accessibility for every individual. Given the nearly infinite variety and degree of disability, the guideline developers focused on steps that would be feasible for Web content developers given technologies and methods available now or in the near future. Furthermore, in order to rate the importance of these steps (checkpoints), the developers of the document focused evaluating the _impact_ of these steps on a small group of disability groups: blind, low vision [not including color deficit], color deficit, deaf-blind, deaf, hard of hearing, cognitive disability, learning disability, physical disability, seizure disorder [except photosensitive epilepsy], and photosensitive epilepsy. This means that priority ratings do not necessarily reflect the importance of a checkpoint for other disability groups (e.g., emotional disability) or upon sub-groups, except as they contribute to the rating for a group as a whole (e.g., dyslexia within the learning disability group) {EH: 23Mar99-1312. I strongly suggest making the set of reference groups explicit. For one thing, we will get better review of the document because they will know better how to interpret the ratings.}{EH, 22Mar99-1533. Important issue} === CMN: This is not strictly accurate. The developers attempted to focues on all disabilities, and review should have likewise focussed on all disabilities. EH: 2. Impact {EH: Definition for the glossary} "Impact" is the adverse effect upon Web page accessibility caused by violation of a checkpoint. For each checkpoint, the priority was assigned based on impact on a reference set of disability groups (blind, low vision [not including color deficit], color deficit, deaf-blind {EH: 23Mar99-1503.}, deaf, hard of hearing, cognitive disability, learning disability, physical disability, seizure disorder [except photosensitive epilepsy], and photosensitive epilepsy). Specifically, if violation of a checkpoint would make it "impossible" for one or more groups to access information in a document, then the checkpoint was assigned a Priority 1 importance level. If violation of a checkpoint would make it "difficult" for one or more groups to access information in a document, then the checkpoint was assigned a Priority 2 level. If violation of a checkpoint would make it "somewhat difficult" for one or more groups to access information in a document, then the checkpoint was assigned a Priority 3 level. {EH: 23Mar99-1503.} CMN: This is a rewrite of the definitions of priority, which I do not think is necessary in the document. EH: The estimate of impact assumes that the disability group is accessing typical content under conditions typical for that group. "Typical content" means a typical mix of different types of Web information purposes (educational, informational, entertainment, commerce) and the different media (text, graphics, video, audio) used by the general population of Web users. "Typical conditions" means technological and environmental conditions typically encountered by the group when using the Web. A typical diversity of technologies that is typically used by members of the group (screen reader, old browser, new browser, personal computer, other Web-capable hardware and software) under a mix of environmental conditions (background noise, illumination, etc.). CMN: I don't think this is true. EH: The conditions and content are those which exist or are expected to exist during the period 1999 through 2010. CMN: I explicitly disagree. EH: === 3. Text Equivalents For Non-Text Objects {EH: Is "objects" OK?} {EH:23Mar99-1254. This may be helpful somewhere.} The key practice that enables accessibility is that of ensuring that there is a appropriate underlying text representation for all {EH:23Mar99-1023. Added "all"}Web content. This text can be rendered in synthesized speech, braille, or visually-displayed text, as need by the user. The document does not discourage the use of other media (graphics, sound, video, etc.), but it is essential that there be text-based alternatives to these non-text media.. === 4. Basic Requirements for Web Accessibility {EH:23Mar99-1254. This may be helpful somewhere.} CMN: While an interesting exercise, I do not feel that this is needed in the document itself. I would also suggest that there are needs for people with physical difficulties. EH: How does one begin to think about making Web content accessible to people in these disability groups? A good place to start is to think about what it would take to make a Web site accessible to individuals who are both deaf and blind. An individual who is deaf-blind cannot hear or see and therefore are unable to access Web content, which usually assumes both visual and auditory senses. But most deaf-blind individuals have a sense of touch -- a tactile sense -- and therefore could receive information via braille. Braille displays allow Web users who are deaf-blind to receive braille information from computers. Special software can take text from the Web site and output it, line by line to a braille display that raises or lowers dot patterns representing the braille characters. How does one take a Web site with text, graphics, audio, and video and make it accessible to a person who is deaf-blind and using a braille display? The braille display can use text directly, but what about the other media? A "text equivalent" must be created for each non-text object or element. For each image, there must be text that, when rendered by a user agent (e.g., browser) will allow the user to know the purpose and function of the graphic. For example, considering a video with accompanying audio. One must generate a text transcript that describes the sounds, visual actions, and spoken dialogue. When text equivalents for the various non-text components have been generateed and organized for Web delivery, the person can access the content via the braille display. How does the situation differ for other disability groups? Fortunately, when one has brought down the access barriers for individuals who are deaf-blind, one has gone most of the distance for people in other disability groups. Individuals whose only disability is blindness can also benefit from braille, however, many prefer using the same text source used by the braille display and having it read aloud using speech synthesis technology. Individuals who are blind can also benefit directly from prerecorded audio if their computer is capable of it. Individuals who have only deafness as a disability can benefit directly from the visual information -- be it text or non-text -- but require the text equivalent for the prerecorded audio. Individuals with physical disabilities, such as inability to move limbs, hands, or head do not ordinarily need any additional provision from the Web content developer. Other disabilities groups need only relatively small provisions from Web content developers. For example, certain ways of handling colors will ensure that individuals with color deficits can see the content on the screen {EH: or "display"). Avoiding flicker will help individuals with photosensitive epilepsy avoid seizures when accessing Web content. Generally speaking, if one ensures that Web content is accessible to individuals who are deaf-blind, relatively little additional effort is required. One the necessary text equivalents have been generated, most of the other accommodation needed by other this and other groups disability groups is provided by the user agent (e.g., browser) and, if necessary, by additional assistive technology (braille or speech technology, special input devices, etc.). Readability of Language. One additional and very important accessibility issues is the readability of the language. Because of the central importance of text for people with diabilities, it is essential that the language be clear and simple, yet appropriate for the site's content. This is especially critical for people with language-related disabilities, such as cognitive disabilities, learning disabilities, and deafness. --Charles McCathieNevile mailto:charles@w3.org phone: +1 617 258 0992 http://www.w3.org/People/Charles W3C Web Accessibility Initiative http://www.w3.org/WAI MIT/LCS - 545 Technology sq., Cambridge MA, 02139, USA
Received on Tuesday, 23 March 1999 16:43:42 UTC