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Re: Changes in Terms and Definitions

From: Charles McCathieNevile <charles@w3.org>
Date: Wed, 20 Oct 1999 18:37:59 -0400 (EDT)
To: eric hansen <ehansen@ets.org>
cc: w3c-wai-au@w3.org, jutta.treviranus@utoronto.ca
Message-ID: <Pine.LNX.4.20.9910201834190.16157-100000@tux.w3.org>
Thanks Eric.

I will incorporate changes from this and and some more from your last memo
into the draft tomorrow.

regards

Charles McCN

On Wed, 20 Oct 1999, eric hansen wrote:

  Changes in Terms and Definitions
  
  I think that a few changes are needed to make definitions more consistent 
  with WCAG 1.0. This message is a follow-up to my earlier message 
  (http://lists.w3.org/Archives/Public/w3c-wai-au/1999OctDec/0043.html)
  
  "//Issue G-19: There is a cluster of terms that seems to be defined 
  imprecisely or are used and not defined. Among the defined terms that need 
  refinement are: accessibility information, alternative presentations, 
  alternative information, accessible, accessibility. Among the undefined 
  terms are: alternative representations, equivalent information, textual 
  alternatives, audio descriptions, should be auditory descriptions, 
  alternative information, accessibility information, descriptive text 
  equivalents, text equivalent, caption, auditory description, collated text 
  transcript, transcript, refreshable braille display(?), DTD,. Having so 
  many terms with partly (or completely) overlapping meanings causes lack of 
  clarity and usability of the document. These meanings need to be added, if 
  necessary, and then clarified. Whenever possible this document should use 
  terms already defined in the WCAG document.//"
  
  I don't think that all these issues cited in that memo have been fully 
  addressed, but on my latest review, the following two stood out.
  
  1. Video Captions
  
  Problem:
  
  The definition of "video captions" in the Terms section does not seem 
  accurate. Its emphasis on describing "action" as well as "dialog" seems 
  quite inaccurate. I have changed the text to correct those problems. I have 
  also inserted it into the definition of "Alternative Presentations and 
  Alternative Information" since the other, parallel terms ("collated text 
  transcript", "auditory description", etc.) do not seem to be broken out 
  separately.
  
  Old (10/14/99):
  
  Video Captions
  A video caption is a textual message that is stored in the text track of a 
  video file. The video caption describes the action and dialog for the scene 
  in which it is displayed.
  
  Proposed:
   
  "Captions" are essential text equivalents for movie audio. Captions consist 
  of a text transcript of the audio track of the movie (or other video 
  presentation) that is synchronized with the video and audio tracks. 
  Captions are generally displayed visually and benefit people who can see 
  but are deaf, hard-of-hearing, or cannot hear the audio (e.g., in a noisy 
  room).
  
  Note 1: For comparison, see the following from the definition of 
  "equivalent" in WCAG 1.0.: "A caption is a text transcript for the audio 
  track of a video presentation that is synchronized with the video and audio 
  tracks. Captions are generally rendered visually by being superimposed over 
  the video, which benefits people who are deaf and hard-of-hearing, and 
  anyone who cannot hear the audio (e.g., when in a crowded room)."
  
  Note 2: If the individual definitions were broken out, it might be 
  something like the following: "Captions"[:]"Captions consist of a text 
  transcript of the auditory track of a video presentation (e.g., movie) that 
  is synchronized with the visual and auditory tracks. Captions are generally 
  displayed visually and benefit people who can see but are deaf, 
  hard-of-hearing, or cannot hear the audio (e.g., in a noisy room)."
  
  ====
  
  2. Alternative Presentations and Alternative Information
  
  Problem:
  
  The definition of  "Alternative Presentations and Alternative Information" 
  should be clarified to make it more consistent with the WCAG 1.0 document. 
  The phrase "captions of the audio" seems misleading since captions are 
  relevant for the auditory track of a movie but not for ordinary audio clips,
   for which the term "text transcript" is used. The apparent reference to 
  human population growth must be fictional; I know of no geographical region 
  that has had such growth. Hence, I provided a different example that I 
  think might be more feasible. The reference to "textual representations of 
  each of these" is inaccurate since some of the examples are already 
  "textual representations."
  
  Old (10/14/99):
  
  Alternative Presentations and Alternative Information
  Certain types of content may not be accessible to all users (e.g., images 
  or audio presentations), so alternative representations are used, such as 
  transcripts for audio, or short functionally equivalent text (e.g., "site 
  map link") and/or descriptive text equivalents (e.g., "Graph 2.5 shows that 
  the population has doubled approximately every ten years for the last fifty 
  years, increasing from about 10 million to 330 million in that time"). An 
  object may have several alternative representations, for example a video, 
  captions of the audio, audio description of the video, a series of still 
  images, and textual representations of each of these.
  
  Proposed:
  
  The following version brings the material into closer conformity to the 
  WCAG 1.0 document.
  
  Alternative Presentations and Alternative Information
  Certain types of content may not be accessible to all users, so alternative 
  representations are used. For example, "text equivalents" are provided for 
  all non-text elements because text can be flexibly output in ways that are 
  usable to diverse populations. Specifically, text can be output 
  _auditorially_ via synthesized speech for individuals who have visual or 
  learning disabilities, _tactually_ via braille for individuals who are 
  blind, or _visually_ via visually-displayed text for individuals who are 
  deaf or are non-disabled. Text equivalents for _still images_ can be short 
  ("Site Map Link") or long (e.g., "Figure 4 shows that the population of 
  bacteria doubled approximately every twenty hours over the first one 
  hundred hours, increasing from about 1000 per milliliter to about 32,000 
  per milliliter."). Text equivalents for _audio clips_ are called "text 
  transcripts." "Captions" are essential text equivalents for movie audio. 
  Captions consist of a text transcript of the audio track of the movie (or 
  other video presentation) that is synchronized with the video and audio 
  tracks. Captions are generally displayed visually and benefit people who 
  can see but are deaf, hard-of-hearing, or cannot hear the audio (e.g., in a 
  noisy room). Another essential text equivalent for a movie is a "collated 
  text transcript," which combines (collates) caption text with text 
  descriptions of video information (descriptions of the actions, body 
  language, graphics, and scene changes of the video track). Collated text 
  transcripts are essential for individuals who are deaf-blind and rely on 
  braille for access to movies and other content. An essential non-text 
  equivalent for movies is "auditory description" of the key _visual_ 
  elements of a presentation. The description is either a prerecorded human 
  voice or a synthesized voice (recorded or generated on the fly). The 
  auditory description is synchronized with the audio track of the 
  presentation, usually during natural pauses in the audio track. Auditory 
  descriptions include information about actions, body language, graphics, 
  and scene changes.
  
  ====
  Appendix: Definition of "Equivalent" From WCAG 1.0 
  
  Equivalent Content is "equivalent" to other content when both fulfill 
  essentially the same function or purpose upon presentation to the user. In 
  the context of this document, the equivalent must fulfill essentially the 
  same function for the person with a disability (at least insofar as is 
  feasible, given the nature of the disability and the state of technology), 
  as the primary content does for the person without any disability. For 
  example, the text "The Full Moon" might convey the same information as an 
  image of a full moon when presented to users. Note that equivalent 
  information focuses on fulfilling the same function. If the image is part 
  of a link and understanding the image is crucial to guessing the link 
  target, an equivalent must also give users an idea of the link target. 
  Providing equivalent information for inaccessible content is one of the 
  primary ways authors can make their documents accessible to people with 
  disabilities. As part of fulfilling the same function of content an 
  equivalent may involve a description of that content (i.e., what the 
  content looks like or sounds like). For example, in order for users to 
  understand the information conveyed by a complex chart, authors should 
  describe the visual information in the chart. Since text content can be 
  presented to the user as synthesized speech, braille, and 
  visually-displayed text, these guidelines require text equivalents for 
  graphic and audio information. Text equivalents must be written so that 
  they convey all essential content. Non-text equivalents (e.g., an auditory 
  description of a visual presentation, a video of a person telling a story 
  using sign language as an equivalent for a written story, etc.) also 
  improve accessibility for people who cannot access visual information or 
  written text, including many individuals with blindness, cognitive 
  disabilities, learning disabilities, and deafness. Equivalent information 
  may be provided in a number of ways, including through attributes (e.g., a 
  text value for the "alt" attribute in HTML and SMIL), as part of element 
  content (e.g., the OBJECT in HTML), as part of the document's prose, or via 
  a linked document (e.g., designated by the "longdesc" attribute in HTML or 
  a description link). Depending on the complexity of the equivalent, it may 
  be necessary to combine techniques (e.g., use "alt" for an abbreviated 
  equivalent, useful to familiar readers, in addition to "longdesc" for a 
  link to more complete information, useful to first-time readers). The 
  details of how and when to provide equivalent information are part of the 
  Techniques Document ([TECHNIQUES]). A text transcript is a text equivalent 
  of audio information that includes spoken words and non-spoken sounds such 
  as sound effects. A caption is a text transcript for the audio track of a 
  video presentation that is synchronized with the video and audio tracks. 
  Captions are generally rendered visually by being superimposed over the 
  video, which benefits people who are deaf and hard-of-hearing, and anyone 
  who cannot hear the audio (e.g., when in a crowded room). A collated text 
  transcript combines (collates) captions with text descriptions of video 
  information (descriptions of the actions, body language, graphics, and 
  scene changes of the video track). These text equivalents make 
  presentations accessible to people who are deaf-blind and to people who 
  cannot play movies, animations, etc. It also makes the information 
  available to search engines. One example of a non-text equivalent is an 
  auditory description of the key visual elements of a presentation. The 
  description is either a prerecorded human voice or a synthesized voice 
  (recorded or generated on the fly). The auditory description is 
  synchronized with the audio track of the presentation, usually during 
  natural pauses in the audio track. Auditory descriptions include 
  information about actions, body language, graphics, and scene changes. 
  
  
  =============================
  Eric G. Hansen, Ph.D.
  Development Scientist
  Educational Testing Service
  ETS 12-R
  Rosedale Road
  Princeton, NJ 08541
  (W) 609-734-5615
  (Fax) 609-734-1090
  E-mail: ehansen@ets.org 
  

--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 Wednesday, 20 October 1999 18:38:03 UTC

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