- From: Ian Jacobs <ij@w3.org>
- Date: Fri, 21 Jul 2000 20:31:35 -0400
- To: asgilman@iamdigex.net, w3c-wai-ua@w3.org
Hello, At the 20 July teleconference [1], Eric Hansen suggested that the UA Guidelines (presumably including the 7 July draft [2]) uses the terms style/content inconsistently: "In some places, we don't distinguish style and content, in others we do. We need to elaborate our definition of content." The definition of "content" in that draft says that "content refers to the document object as a whole or in parts." The document object definition says that "the document object is the user agent's representation of data (e.g., a document)." This would include style sheets. I think we should leave this definition as is. For distinguishing structure from presentation (both conveyed in content) I propose that we do what was done in the Authoring Tool Guidelines, which defines the terms structural markup [3] and presentation markup [4]. I propose that we reuse or adapt those definitions (quoted below) as necessary. All of this relates to issue 297 [5], which is entitled "Style v. content and background sounds" (the title needs fixing since it opposes style and content). The question is how much UA control is required over certain types of content, notably when that content is used to achieve a presentation effect? I think that the answer depends on the type of content: 1) Users need full control of content whose purpose is not a presentation effect. The first question is: can we distinguish content intended for a presentation effect from content not intended for a presentation effect? My answer would be: the best we can do is rely on what we can recognize as being for style: HTML transitional elements and attributes, style sheets, known non-standard markup such as bgsound. (Yes, authors may misuse structural markup for a presentation effect and vice-versa.) Note that I don't have a term for "content not intended for a presentation effect." I think we tend to use the term "content" (meaning "having information") here, and that's the source of the inconsistency. We can oppose style and structure, and style with non-style. Do we need a term for "non-style"? (I hope we don't.) I would also note that this discussion sounds a little like the discussion about content meant for humans v. content meant for machines. Refer to Al's comments on this topic [7]: "The distinction between data (raw content) and meta-data (markup) is an artifact of the view assumed by the author. There is no fundamental semantic difference between what is called data vs. metadata. They both play the same role as bearers of information Semantically, it is all just one class of data. This is a little-understood fact of information science." Al, will you make the same comment about an assertion that presentation v. non-presentation (or structure)? 2) Users also need control of content whose purpose is for presentation, but the level of control depends on the nature of the content (I would argue). In some cases, "on/off" control may not suffice for providing access. For example, the user needs to be able to select a font family that provides access (and can't just turn off fonts). In other cases, I think that on/off control suffices; access is made possible by being able to turn off blinking content, animations used for decoration, and background sounds used for decoration. While fine tune control might be useful, I think that a requirement to turn off the interfering content is the Priority 1 requirement. I think my proposal for issue 5 that arose during the Mac IE evaluation [6] is still appropriate in this light. - Ian P.S. The proposal should include a comment that independent control of volume for different audio sources should NOT be required for background sounds. The user must be able to configure the UA to not render this merely decorative sound, and that should suffice. [1] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000JulSep/0097.html [2] http://www.w3.org/WAI/UA/WD-UAAG10-20000707 [3] http://www.w3.org/TR/2000/REC-ATAG10-20000203/#def-structural-markup [4] http://www.w3.org/TR/2000/REC-ATAG10-20000203/#def-presentation-markup [5] http://cmos-eng.rehab.uiuc.edu/ua-issues/issues-linear.html#297 [6] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000JulSep/0060.html [7] http://lists.w3.org/Archives/Public/w3c-wai-ua/2000AprJun/0210.html -- Ian Jacobs (jacobs@w3.org) http://www.w3.org/People/Jacobs Tel: +1 831 457-2842 Cell: +1 917 450-8783 "Structural markup" is markup language that encodes information about the structural role of elements of the content. For example, headings, sections, members of a list, and components of a complex diagram can be identified using structural markup. Structural markup should not be used incorrectly to control presentation or layout. For example, authors should not use the BLOCKQUOTE element in HTML [HTML4] to achieve an indentation visual layout effect. Structural markup should be used correctly to communicate the roles of the elements of the content and presentation markup should be used separately to control the presentation and layout." "Presentation markup" is markup language that encodes information about the desired presentation or layout of the content. For example, Cascading Style Sheets ([CSS1], [CSS2]) can be used to control fonts, colors, aural rendering, and graphical positioning. Presentation markup should not be used in place of structural markup to convey structure. For example, authors should mark up lists in HTML with proper list markup and style them with CSS (e.g., to control spacing, bullets, numbering, etc.). Authors should not use other CSS or HTML incorrectly to lay out content graphically so that it resembles a list.
Received on Friday, 21 July 2000 20:31:46 UTC