Inline TOC raises warnings

[jfbu]

\DocumentMetadata{
 uncompress,
 pdfversion=1.7,
 lang=en-US,
 testphase=phase-III
}
\documentclass{article}
\usepackage{etoc}
\begin{document}
\etocsetstyle{section}
  {(start) }
  {\etocname, }%
  {}
  {(end) }%

% The TOC contents with default TOC title starts in vmode.
% With empty TOC title it will depend if \tableofcontents
% is issued when in horizontal mode: by default etoc
% does \par, but \etocinline suppresses that.

\etocinline % avoids an added \par before title

\etocsettocstyle{}{} % no title

This is an inline TOC
\tableofcontents
and the end of the paragraph.

\section{One}

Text

\section{Two}

Text

\end{document}

First warning is

Package tagpdf Warning: Parent-Child 'P/' --> 'TOC/pdf'.
(tagpdf)                Relation is not allowed (struct 5, /text --> struct 6)
(tagpdf)                on line 29

[jfbu]

I need some help here on whether it is at all possible to insert in a paragraph a PDF tagging TOC structure.

ping @u-fischer if you get this and have time.

[u-fischer]

The PDF-paragraph (the P tag mentioned in the message) is rather a pain as it has lots of restrictions regarding its children. We therefore do not use it for full paragraphs but only for small pieces. A full paragraph is instead surrounded by a tag text-unit (which is role mapped to Part). (Some background about this can be found in latex-lab-block.pdf in section 3 "tagging support").

So a list inside a paragraph

some text \begin{itemize}\item list item \end{itemize} more text 

is tagged like this:

<text-unit> %= Part
  <text> %= P
     some text
  </text>
  <L> <LI> <LBody> list item </LBody></LI></L>
  <text>more text</text>
</text-unit>

Basically you should do something similar and interrupt the P/text tag. The coding is not necessarly trivial if the inner structure (e.g. the list) contains \par's, as you have to decide if you restart a after the list or not, we use the @doenpe switch for this.

It is not very beautiful, but not illegal to produce empty structures or mc-chunks.

[jfbu]

Thanks a lot @u-fischer! Based on your help I did a preliminary implementation for tagging inline TOCs. It is certainly much too naive but works with the gh9 and gh11 test files which I checked on ngpdf.com. The tree looks ok there. In the HTML conversion I noticed that text chunks from the input originating in the user custom TOC line styles disappear, which is expected as I tried to mark them as artifacts. Also disappearing from the HTML conversion is some text from user custom \etocaftercontentshook (which is done after the tagged TOC contents) which maybe an after-effect of the preliminary way I handled the present issue #11.

A probably very bad point is that I use \ifhmode rather than querying via tagpdf interface if really we are in <text-unit><text> situation.

As per the #9 which was fixed earlier, I realized the issue originated from the fact that after borrowing from kernel the before and after \@starttoc tagging hooks, it was mandatory to issue \par before exiting the scope limiting group.

edit1: when the TOC contents got started in vertical mode...

edit2: and if the "after hook" was executed while still in paragraph mode, rather. Then a \par had to be inserted before terminating the scope limiting group always added by etoc around the whole TOC structure: i.e. this includes both the contents and the user or etoc-emulating-the-class before and after style, such as a title before and a rule after.