Re: equations in HTML

Brian Gaines (gaines@fsc.cpsc.ucalgary.ca)
Mon, 12 Sep 1994 13:53:49 -0600


Date: Mon, 12 Sep 1994 13:53:49 -0600
Message-Id: <199409121953.NAA02878@fsc.cpsc.ucalgary.ca>
From: "Brian Gaines"  <gaines@fsc.cpsc.ucalgary.ca>
To: www-html@www0.cern.ch
Subject: Re: equations in HTML

In message <m0qkGot-000FVHC@covina.lightside.com>  writes:
> Equations, especially those that are likely to be placed in-line (as
> opposed to those in their own paragraph), have a natural baseline. For
> example,
>                         ___________
>                        |     b - c |
>    Here is an equation:|a + -------|.
>                        |       2   |
>                        |___________|
> 
> In this equation, the baseline of "a" should align with the surrounding
> text. Unfortunately, the <img...> tag allows only top, middle, or bottom
> alignment. What is needed is to be able to specify a distance from the
> bottom edge of the image to the internal baseline.
> 
> I believe the utility of this kind of alignment is not limited to math,
> chemical equations have similar requirements. In fact, any text-based
> notation will generally benefit from such an alignment feature.

Since images are fetched separately the best way to deal with this is
for the image data structure to carry the information. Intelligent clients
can then offer exact placement, and others can just put them where they
wish.

GIFs have provision for cutomizable annotation which is both easy to
add and decode. Other graphic formats have similar facilities.

It is better to carry such layout information in the data structures
of the graphic objects rather than overload HTML with duplicate information.

b.

Brian Gaines              Knowledge Science Institute, University of Calgary
gaines@cpsc.ucalgary.ca   Calgary, Alberta, Canada T2N 1N4