[jahewson]

> I wish PDFs had a reflowable mode. What would it take to add such a mode to the PDF spec without breaking backward compatibility?

PDF has everything including the kitchen sink. There’s a fairly esoteric feature called “tagged PDFs” which contain extra markup commands within the page description that map it to a logical structure and alternative textual presentations (e.g. MathML). The problem is that nobody uses it as it’s extremely hard to generate (most software which does text layout discards high level semantic details fairly early on, making it hard to retrofit - pdfTeX for example only recently started inserting space characters between words!). Likewise PDF viewers don’t bother to support it.

Reflowing a tagged pdf is fairly easy... once you have the pdf, which of course you don’t.

It’s a hard problem.

[oefrha]

I heard tagged PDF is one of the goals of LaTeX3, and LaTeX3 work has thus far been available as packages on top of LaTeX2e, which means it should work on LaTeX2e too. I’ve never tried it though.

[adiM]

ConTeXt supports tagged pdf out of the box