[accessibility] Current packages and methods of generating tagged PDF from LaTeX

[Ross Moore]

Hi Chris,

On 28 Jun 2019, at 2:53 pm, Christopher Rowley <c.a.rowley at icloud.com<mailto:c.a.rowley at icloud.com>> wrote:


On 28 Jun 2019, at 10:53, Ross Moore <ross.moore at mq.edu.au<mailto:ross.moore at mq.edu.au>> wrote:

 … so you are asking for an appropriate (software) Functor, to map/export to XML schemas.

No, the other way.  To take an existing schema and help to produce the equivalent PDF objects to support tagging against this schema.

This actually sounds similar to what I’m doing with document classes.

Upon recognising some structured text blocks, I look at what macros were used in the document class.
(think e.g., author names and addresses)
Then I work out how these should be tagged, to capture the structure.
Next I have to patch the LaTeX macros to include extra routines that create the appropriate tagging,
as well as using the formatting and styles in the same way as in the original class.

The routines for the tagging have to be aware enough so as to not upset kerning, penalties and \lastskip.
(I spent several days getting italic corrections right!)
It really does get down to that kind of low-level TeX programming.



Authors and addresses is particularly apt for this, since the addresses
do not need to appear directly after the names.
In many AMS documents, the addresses appear at the end of the document,
but the information for them occurs often in the LaTeX preamble.

Structurally each address comes with the author’s name,
but its visual location can be elsewhere within the PDF.

Similar ideas apply to tagging for floats, which are declared in one place,
but boxed away to occur somewhere else.
Getting the PDF structured correctly requires using a “history” file,
which records which page the float occurred on during the previous LaTeX run.
This is the same idea as with labels and cross-references, bib-items, etc.



We can discuss the category theoretic approach elsewhere!:-)

Chris


Cheers,

Ross


Dr Ross Moore
Department of Mathematics and Statistics
12 Wally’s Walk, Level 7, Room 734
Macquarie University, NSW 2109, Australia
T: +61 2 9850 8955  |  F: +61 2 9850 8114
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