Image descriptions that require math

[Thomas Judson]

I am trying to write an image description for the following commutative diagram (AKA alt-text). I don’t see how to do this without using math symbols. PreTeXt does not seem to complain if I write


<m>\psi: E[x]/\langle p(x) \rangle \to F[x]/\langle q(x) \rangle</m>

or

\psi: E[x]/\langle p(x) \rangle \to F[x]/\langle q(x) \rangle

Right now, I am inclined to leave everything in math mode. Any comments on best practices?

Tom

[David Farmer]

It seems like a step in the wrong direction to have that as an
image. Doesn't MathJax handle commutative diagrams where the arrows
are only vertical or horizontal?

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[Thomas Judson]

Quite possible.  This image might be a relic from times past.  I will look into it.

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[Mitch Keller]

David’s suggestion is a good one, but I will throw in a vote for alt text allowing/encouraging <m> tags in hopes that a screen reader can dig into them and process them, but that’s probably a question for the MathJax folks.

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[Alex Jordan]

Right now an image description goes into the alt attribute of the img in HTML.

The content of the alt attribute should be plain text. For example, I'm not aware

that MathJax has some way to look into an alt attribute of an image and do

anything with it. (Also it feels like an HTML attribute abuse to use something

other than text, but maybe that is just me feeling and not relevant.)

So as long as we are talking about providing an image description to the user

via the alt attribute (that is, doing things in the standard way) then for practical

reasons I would not let math content into a description.

An alternative to the standard way of doing things would be to not use "img"

for the image, and to use something like "object" instead. The child content

of the "object" is supposed to be the fallback content when the "object"'s

@data isn't available. But I think this alternative would be asking for trouble

with different browsers and screen readers not ready to use "object" the way

it was envisioned to be used.

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[Rob Beezer]

The alt *attribute* in HTML is an *attribute*. So you are severely limited in
(a) what you can put there, and (b) what you can do with it.

For example, if you put a quote mark in the PTX "description", then the HTML
will be wrecked. So the PTX expectation is that "description" carries no
elements at all and will go into @alt verbatim.

An extreme suggestion would be to allow "m" tags and run MathJax Speech Rule
Engine over it on the side and somehow put it back in place in the output.

A more practical answer might to imagine how the six objects of that diagram
would be verbalized, and then say things like "A three row, two column layout.
With arrows going... With row one, column one being E bracket x mod..."

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> Thomas W. Judson, Professor
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