The whole PDF business is focusing our attention on the
definition of accessibility. We need to work this out, and we
will continue to work it out as neeeds and technologies change.
If I try to do a braille translation of a document, it might
come in three different forms: a print image file, a WordPerfect
file that is properly coded so that as you scale its font size up
or down, the basic layout does not change; or a tagged file, such
as SGML or .MEG MegaDots file, where everything has a tag showing
where it belongs in the document's structure or outline.
Many aspects of proper braille formatting can be gleaned from
the appearance of a document, as represented in PDF or in coded
WordPerfect files. But too many people treat their word
processor like a typewriter, and don't know how to code something
so that it is scalable, or even see the need for scalability.
Even in a properly coded WP file, there must be a combination of
automated and manual methods to determine how best to restructure
the document for Braille.
Until we start working with style-based Braille translation
systems like MegaDots and the new Duxtury, we have a hard time
even explaining the advantages of putting structure into
documents, and not just appearance.
You need to hear Dr. Raman's system for reading equations in
synthetic speech. It takes advantage of the structure of a TeX
document to "display" the different levels of an equation with
different degrees of volume, left-right placement, head size, and
other characteristics so you can hear what is a superscript, the
numerator and denominator of a complex fraction, nested
parentheses, etc. It would have to be under the user's control,
and not recorded on a tape, so the reader can ask the machine for
the level of detail desired at a particular time.
In summary, there are times when it is vital to know the
appearance of a document. But there are going to be other times
when the structure is more important than the appearance,
especially if we want to do more than a passing job of
translating a document into speech, braille or large print.
Lloyd Rasmussen
rasmusse@mail.loc.gov
l.rasmussen2@genie.geis.com
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