[tex4ht] Subsubsections do not show up in TOC

[Michal Hoftich]

Hi Jürgen,



On Tue, Feb 22, 2022 at 11:39 AM Jürgen Hubert <jhubert at gmx.de> wrote:
>
> After I recently updated my LaTeX installation (which I hadn't done for more than a year), I suddenly had the problem that subsubsections no longer show up in the TOC of the EPUB file:
>

I think the issue was caused by the TeX4ebook update two years ago. It
explicitly uses the list of sectioning commands that should be
included in the Epub TOC, and it doesn't include \subsubsection. I've
changed that in the development version of TeX4ebook, so now it does.
Unfortunately, I updated TeX4ebook on CTAN a few days ago, so it will
take some time before the next release. You can install the
development version to test if it fixes it for you.

> The end result is that the Chapter, Section, and Subsection show up in the TOC, but the Subsubsection does not. Since I was able to generate files with Subsubsections in the TOC in the past before the update, the logical conclusion seems to be that something went wrong during the update process. And the warnings
>
> [WARNING] tocid: char-def module not found
> [WARNING] tocid: cannot fix section id's
>
> are also new.
>
> Now, I was able to find the "char-def" module in a repository,
>
> https://raw.githubusercontent.com/adityam/context-math/master/char-def.lua
>
> I am unsure how to install it so that tex4ebook will find it.
>
> Can anyone give me some advice on how to proceed?

This warning is not that important, it just means that make4ht cannot
assign id attributes based on the text content to sectioning elements.
So \section{Hello world} will become something like <h2
id="hello-world">. It is good for linking to web pages, as you can
link to that section as <a href="hello.html#hello-world">... instead
of <a href="hello.html#x1-22x">, which is used by default.

If you want to get rid of this warning, you can try to install ConTeXt
package on your system.

Best regards,
Michal