Re: DOCBOOK-APPS: Re: XSL implementation of DBTeXMath

[Michael Smith <smith at xml-doc dot org>]

Jirka Kosek <jirka@kosek.cz> writes:

> Norman Walsh wrote:
> 
> > With respect, I think that's abuse of the alt tag. Might I suggest instead
> > supporting this with:
> 
> I don't want abuse alt. But from my reading of alt element description
> in TDG:
> 
> ----
> Description
> A text (or other nonvisual) description of a graphical element. This is
> intended to be an alternative to the graphical presentation. 
> 
> Parents
> These elements contain alt: equation, informalequation, inlineequation.
> ----

The TDG reference page for Inlineequation:

  http://www.oreilly.com/catalog/docbook/chapter/book/inlineequation.html

actually has the same contents for <alt> that you've described:

  <inlineequation>
    <alt>e=mc^2</alt>
    <graphic fileref="figures/emc2"></graphic>
  </inlineequation>

But I guess that's a case of a very simple equation for which the Tex
math happens to match the meant-to-be-human-readable text description.

Looking at the TDG examples for the other equation elements:

  <equation><title>Fermat's Last Theorum</title>
    <alt>x^n + y^n &ne; z^n &forall; n &ne; 2</alt>
    <graphic fileref="figures/fermat"></graphic>
  </equation>

  <informalequation>
    <alt>e^(pi*i) + 1 = 0</alt>
    <graphic fileref="figures/epi10"></graphic>
  </informalequation>

...I guess maybe you can infer that the DocBook TC intended the
contents of <alt> to be a *human-readable* text description, using ISO
entities for any math symbols that couldn't be represented with normal
characters.

But maybe if you use <alt role="tex">, you could tweak the stylesheets
so that to the HTML output they add some generated text like:

  <img alt="Tex version of equation: [Tex stuff]">

That way, to people reading or hearing the alt text in a browser,
it'll at least be unambiguous to them that what's they're reading/
hearing is Tex math -- which, depending on the complexity of the
equation, they may or may not find "human-readable".

Just my two yen,

  --Mike