Re: Structure vs. Value and Contradictory Criteria

SC  1.3.1  does require this. 

gregg

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Gregg Vanderheiden
gregg@raisingthefloor.org




> On Oct 22, 2015, at 2:10 PM, Wayne Dick <wayneedick@gmail.com> wrote:
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> It might not be possible to avoid all conflict, but whenever possible guidelines and criteria should address access to language structures and parameter values rather than prescription of specific values.  
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> Since this is abstract let me be specific.  Languages that can be read by machines like HTML with CSS, PDF, Flash and Silverlight have one thing in common. They have structures that can be determined programmatically, otherwise machines could not read them.  The structures that can be determined programmatically can be changed with 100% accuracy. Other structures cannot.  
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> Example: Tags for lists in PDF along with their meaning to the content can be determined programmatically. The "class" attribute in is assigned a string by the programmer, but a program cannot determine its meaning within the context of the an HTML document. The CSS parameter "color" is given a value that totally determines its meaning within the content. The "span" element has non-deterministic meaning.
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> WCAG should always insist that items that can be exposed deterministically are exposed that way. This will enable change to structures and values required for flexibility.
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> Example: Overriding the authors color choices. if color is primarily determined by foreground and background color attributes values choices these can be changed. Problems with other non-deterministic formats.  A programmer may hide text by making text the same color as background. If you change the colors you make something visible that should not be. This should be a prohibited configuration. It is like using an H1 because you like the font size. A programmer may use a background image. How does an AT modify the foreground color.   You cannot determine the background color programmatically. Is there a deterministic way to do this or how can we change this?  
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> Increasing the determinism of content seems to be a way to expand WCAG without creating conflicts.
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> Wayne
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