Comments from Jacques Distler

Jacques Distler, author of reputedly the most technologically advanced 
Weblog there is (Musings, at <>, 
with valid XHTML 1.1 served correctly *plus* MathML), writes the following 
remarks about WCAG 2, forwarded with permission:

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>    If multiple representations can be retrieved from a URI through
>    content negotiation, then the conformance claim would be for the
>    delivery unit that is returned when no negotiation is conducted
>    (unless the server returns an error for that condition, in which case
>    one of the negotiated forms must comply).

This strikes me as problematic. You pretty much are preventing yourself from 
mandating the use of technology X unless X is supported by, or at least 
tolerably ignored by, the lowest common denominator legacy UA. Or, at least, 
you're saying that sending downgraded content to such legacy UAs should be done 
by means other than Content Negotiation (eg, by UA-sniffing).

Other things that struck me as whacked:


> The em and strong elements were designed to indicate structural emphasis 
> that may be rendered in a variety of ways (font style changes, speech 
> inflection changes, etc.).
> The b and i elements were deprecated in HTML 4.01 and XHTML because they 
> were used to create a specific visual effect.

They were not, and are not deprecated. Ditch the stupid, incorrect sentence 
and keep the correct one that precedes it.

Let me jump to the Math markup section, which is the thing you dragged me into 
this for, anyway:

> Using markup (and style sheets) where possible rather than images (e.g., a 
> mathematical equation, link text instead of image button) promotes 
> accessibility for the following reasons:
>     * Text may be magnified or interpreted as speech or braille.
>     * Search engines can use text information.
> As an example, consider these techniques for putting mathematics on the Web:
>     * Ensure that users know what variables represent,

Make sure you define all technical terms or jargon that you use in your text. 
Symbols in a mathematical equation are *no different*.

>       for example, in the
>       equation "F = m * a", indicate that F= Force, m = mass, a = 
> acceleration.


>     * For straightforward equations, use characters, as in "x + y = z"
>     * For more complex equations, mark them up with MathML [MATHML] or TeX. 
> Note.
>       MathML can be used to create very accessible documents but currently 
> is not as
>       widely supported or used as TeX.

ASTER supports reading TeX.
EmacSpeak supports reading web pages

Both were written by T.V. Raman.

One cannot, however, conclude that there exists *any* assistive technology for 
reading TeX embedded in a web page. T.V. Raman could, presumably, write one. 
But he hasn't.

>     * Provide a text description of the equation

If you could say it in words, you probably wouldn't need an equation, would 

>       and, where possible, use character
>       entity references to create the mathematical symbols.

Do you mean *named* entities (&conint;) or numeric character references 
(&#x0222E;)? Or does it matter?

On general grounds, Henri Sivonen has been beating me over the head that 
X(HT)ML sent over the web should use NCRs, rather than named entities. I have, 
finally, come around to his point of view.

> A text alternative must
>       be provided if the equation is represented by one or more images.


> TeX is commonly used to create technical papers that are converted to HTML 
> for publication on the Web. However, converters tend to generate images, use 
> deprecated markup, and use tables for layout. Consequently, content 
> providers should:
>    1. Make the original TeX (or LaTeX) document available on the Web. There 
> is a system
>       called "AsTeR" [ASTER] that can create an auditory rendition of TeX 
> and LaTeX
>       documents. Note. These tools work primarily in the English environment 
> and may not
>       work so well with speech synthesizers whose primary language is not 
> English.
>    2. Ensure that the HTML created by the conversion process is accessible. 
> Provide a
>       single description of the equation (rather than "alt" text on every 
> generated image
>       as there may be small images for bits and pieces of the equation).

Or use a better converter.


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Received on Friday, 15 July 2005 18:19:47 UTC