The hard question of PDF/UA compatibility etc.

[Omikhleia]

Since June 2025, and the European Accessibility Act (EAA) amongst other, PDF accessibility is an important topic.
For the record, Typst 0.14 now has PDF/A, PDF/UA compliance, etc.

SILE has a 2015-initiated experimental one-shot pdfstructure package which "classes" (such as, therefore, resilient.book) could use.... But, having tried it...

• It's far from general (see Implement PDF Accessibility Support sile-typesetter/sile#110)...
• Reviewing it's code, I have to say... er... it has a very low code quality, is wrong in many places, and totally lacking in others. And the proposed approach here is not only incomplete, but generally wrong in terms of architecture...

Beyond some adaptations of resilient itself, it would require a new approach (involving other SILE "standard" packages and outputters in the mix).

Suggest a path forward.