W3C home > Mailing lists > Public > www-math@w3.org > April 2002

Re: MathML-Presentation specs criticized.

From: David Carlisle <davidc@nag.co.uk>
Date: Tue, 16 Apr 2002 08:38:25 +0100
Message-Id: <200204160738.IAA26854@penguin.nag.co.uk>
To: jimbofc@yahoo.com
CC: www-math@w3.org

> the layout is part of the content, so the
> presentation language should allow multiple layouts of the same code.

No, that is what the content markup is for. Content markup has a default
presenatation form but my be presented in any visual or non visual
format chosen by the rendering agent. But you need some method of
specifying mathematical layouts, that's what the presentation elements
are for. If you want to unambiguously express the idea of a fraction use
<apply><divide/>
<mfrac>expresses the notion of a mathematical layout scheme involving
two terms laid out vertically with a line between. If you know the
context you can of course infer meaning from this mathematical layout
but it is always context dependent.


> (Here's a good (I hope) example.  Visual rendering agents might style an
> mfrac element as two rows separated by a bar.  However, a blind person's
> audio rendering agent might style the mfrac element by saying the
> (insert natural language here) translation of the numerator + "over" +
> the denominator.  The blind person would be confused if it was rendered
> as the numerator + "1 pixel solid bar" + denominator.)

That's one reason for having specific mathematical layout rather than just
re-using generic css styling, mfac can be rendered as "over" in an aural
rendering wheras general css lines are probably ignored altogether as
css styling is purely decorative. But whether it's rendered as two terms
with a line or two spoken phrases and teh word over, it is still
essentially the layout that is being specified, not the mathematical
concept of division.

David

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Received on Tuesday, 16 April 2002 03:39:19 GMT

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