10.4. Problems of the DBTeXMath method

The DBTexMath method provides us with an easy way to get perfectly typeset Mathematics in all 4 formats: HTML, PDF, PS and RTF. Moreover, it does this in the context of SGML processing - we are not forced to leave our usual procedures and/or markup, it integrates nicely in our scripts.

Nevertheless, such an approach to mathematical document processing is not free from problems:

• The most important objection comes from a theoretical viewpoint: the <alt> tag is what its name suggests - a tag for an alternative description of the equation. This is not exactly what the TeX code is, especially from the accessibility point of view (see Chapter 9). In a message to the docbook-apps mailing list, Michael Smith points out the following:

  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"[1].

• Labels on displayed equations for the HTML and RTF formats will always start at 1, no matter how many equations you have. I briefly discussed this in Section 10.2, along with some measures to alleviate the problem. Until some TeX Guru (anyone reading?) out there tells me how to work around this, you might want to crop every image of a displayed equation to 90% in the x direction with the -crop option to convert:

  convert -crop 90x100% images/math/17202.png

  This will eliminate the equation labels from the image. If you follow the rules in Section 10.2, you will still be able to reference equations concisely and correctly through all chapters and in all formats.

• Your text should not contain begintexliteral or endtexliteral, otherwise the unescape_math.pl script will try to unescape some characters between them (and will also delete them). Well, I can live with that one...