% \iffalse meta-comment
%
%% File: latex-lab-firstaid.dtx (C) Copyright 2023-2026 LaTeX Project
%
% It may be distributed and/or modified under the conditions of the
% LaTeX Project Public License (LPPL), either version 1.3c of this
% license or (at your option) any later version.  The latest version
% of this license is in the file
%
%    https://www.latex-project.org/lppl.txt
%
%
% The latex-lab bundle is developed in the LaTeX2e GitHub.
% Issues may be reported at
%
%    https://github.com/latex3/latex2e/issues
%
\def\ltlabfirstaiddate{2026-10-26}
\def\ltlabfirstaidversion{0.86l}
%<*driver>
\DocumentMetadata{tagging=on,pdfstandard=ua-2}
\documentclass{l3in2edoc}

\EnableCrossrefs
\CodelineIndex

\usepackage{todonotes}

\begin{document}
  \DocInput{latex-lab-firstaid.dtx}
\end{document}
%</driver>
%
% \fi
%
% \title{The \textsf{latex-lab-firstaid} package\\
% Temporary patches to external packages needed for the tagging project}
% \author{\LaTeX{} Project\thanks{Initial implementation done by Ulrike Fischer}}
% \date{v\ltlabfirstaidversion\ \ltlabfirstaiddate}
%
% \maketitle
%
% \newcommand{\xt}[1]{\textsl{\textsf{#1}}}
% \newcommand{\TODO}[1]{\textbf{[TODO:} #1\textbf{]}}
% \newcommand{\docclass}{document class \marginpar{\raggedright document class
% customizations}}
%
% \providecommand\hook[1]{\texttt{#1}}
% \providecommand\key[1]{\texttt{#1}}
% \providecommand\insttype[1]{\texttt{#1}}
% \providecommand\instname[1]{\texttt{#1}}
% \providecommand\struct[1]{\texttt{\meta{#1}}}
%
% \NewDocumentCommand\fmi{sO{}m}
%   {\IfBooleanTF{#1}{\todo[inline,#2]{#3}}^^A
%                    {\todo[#2]{#3}}}
%
% \NewDocumentCommand\ufi{sO{}m}
%   {\IfBooleanTF{#1}{\todo[inline,#2]{UFi:#3}}^^A
%                    {\todo[#2]{UFi:#3}}}
%
%
% \begin{abstract}
% \end{abstract}
%
% \section{Introduction}
%
% The following contains small temporary changes to external packages to avoid
% errors with the new tagging code.
%
% Similar to the main firstaid package the goal is to remove the
% patches once the packages have been updated.
%
% \changes{v0.85g}{2024/10/04}{Removed firstaid for blindtext.
%   No longer needed with new \cs{@doendpe} code.}
% \changes{v0.85g}{2024/10/04}{Added firstaid for fancyvrb.}
% \changes{v0.85n}{2025-10-12}{Added firstaid for pgf.}
% \changes{v0.85t}{2026-03-12}{Switch from \texttt{x}- to \texttt{e}-type
%  expansion in expl3 code}
% \changes{v0.85u}{2026-04-24}{Added firstaid for H-floats.}
% \changes{v0.85u}{2026-04-24}{Removed microtype firstaid. No longer needed.}
% \changes{v0.86f}{2026-09-20}{Added support for listings}
% \section{Implementation}
%
%    \begin{macrocode}
%<*package>
%<@@=tag>
%    \end{macrocode}
%    \begin{macrocode}
\ProvidesPackage {latex-lab-testphase-firstaid} [%
   \ltlabfirstaiddate\space v\ltlabfirstaidversion\space
   Temporary patches to external packages needed for the tagging project]
%    \end{macrocode}
%  \begin{macro}[no-user-doc]{\FirstAidNeededT}
%    This is a very simple help to ensure that we only apply first aid
%    to an unmodified package or class. It only works in the case the
%    file has already been loaded and the csname \cs{ver@\#1.\#2} got
%    defined (holding the current date, version, and short description
%    info). We then compare its content to a frozen string and make
%    the modification \verb=#3= only if both agree. If they differ we
%    assume that the package/class in question got updated by its
%    maintainer.
%    \begin{macrocode}
\ExplSyntaxOn
\providecommand\FirstAidNeededT[3]{
  \exp_args:Nce\str_if_eq:onF{ver@#1.#2}{#3}
      { \typeout{==>~ First~ Aid~ for~ #1.#2~ no~ longer~ applied!^^J
          \@spaces Expected:^^J
          \@spaces\@spaces #3^^J
          \@spaces but~ found:^^J
          \@spaces\@spaces \use:c{ver@#1.#2}^^J
          \@spaces so~ I'm~ assuming~ it~ got~ fixed.
      } }
  \exp_args:Nce\str_if_eq:onT{ver@#1.#2}{#3}
}
%    \end{macrocode}
%  \end{macro}
% \subsection{tikz/pgf}
% ti\textit{k}z inputs libraries with the primitive \cs{input} command. This means that
% these libraries are not listed in the file list written by \cs{listfiles} and the new
% tagging status report created with the \texttt{check-tagging-status} key.
%
% We therefore redefine one \texttt{pgf} command to use the \LaTeX{} \cs{input} command.
% Check https://github.com/pgf-tikz/pgf/issues/1424 for changes.
%    \begin{macrocode}
\AddToHook{package/pgfrcs/after}
 {\def\pgfutil@InputIfFileExists#1#2#3{\pgfutil@IfFileExists{#1}{\input{#1}\relax#2}{#3}}}
%    \end{macrocode}
%
% \subsection{listings}
% The \pkg{listings} package needs various adaptions to enable tagging support.
% They are in an external file.
%    \begin{macrocode}
\AddToHook{package/listings/after}[latex-lab-firstaid]{\RequirePackage{latex-lab-listings}}
%    \end{macrocode}
%
% \subsection{AMS classes}
% 
%    Unfortunately, the AMS classes contain a full inline copy of
%    \pkg{amsthm} inside the class (thanks to \pkg{dostrip}) and they
%    use \cs{newcommand}, sigh.
%
%    Thus, to make the new code work with these classes we have to hide
%    some definitions, load the class and only afterwards restore our
%    own versions.
%
%    So first save some of the problematical definitions under some
%    other names (quite a handful):
%    \begin{macrocode}
\let \@kernel@newtheorem      \newtheorem
\let \@kernel@newtheoremstyle \newtheoremstyle
\let \@kernel@theoremstyle    \theoremstyle
\let \@kernel@proof           \proof
\let \@kernel@endproof        \endproof
%    \end{macrocode}
%    
%    \begin{macrocode}
\def\undefine@thm@macros{
  \let \newtheoremstyle \relax
  \let \theoremstyle    \relax
%    \end{macrocode}
%    
%    \begin{macrocode}
  \let \proof           \relax
  \let \endproof        \relax
%    \end{macrocode}
%    These we also have to undefine but there is no need to restore
%    them later (our definitions are identical to those in the
%    classes) we only have to avoid that \cs{newcommand} generates an
%    error when the class is loaded.
%    \begin{macrocode}
  \let \pushQED    \relax
  \let \popQED     \relax
  \let \qedhere    \relax
  \let \mathqed    \relax
  \let \openbox    \relax
}
%    \end{macrocode}
%    
%    Then undefine them just before the class gets loaded:
%    \begin{macrocode}
\AddToHook{class/amsart/before} [block]{ \undefine@thm@macros }
\AddToHook{class/amsbook/before}[block]{ \undefine@thm@macros }
\AddToHook{class/amsproc/before}[block]{ \undefine@thm@macros }
%    \end{macrocode}
%    After the class got loaded we restore the saved versions.
%
%    Most of the first aid code for the AMS classes needs to be applied after
%    the class got loaded.
%    Instead of putting all the code in hooks and thus into the format we now
%    write it to files that are loaded after the class has been loaded.
%    \begin{macrocode}
\AddToHook{class/amsbook/after}[latex-lab-firstaid]{\input{latex-lab-firstaid-amsbook.ltx}}
\AddToHook{class/amsart/after} [latex-lab-firstaid]{\input{latex-lab-firstaid-amsart.ltx}}
\AddToHook{class/amsproc/after}[latex-lab-firstaid]{\input{latex-lab-firstaid-amsproc.ltx}}
%    \end{macrocode}
%
%    \begin{macrocode}
%</package>
%<*amscls>
\ExplSyntaxOn
%    \end{macrocode}
%    
%    Let us first restore the thmlike macros while this is fresh on
%    our mind.  Note that we don't have to restore all the QED-related
%    commands as ours are identical to those defined by the AMS.
%    \begin{macrocode}
  \let \newtheorem      \@kernel@newtheorem  
  \let \newtheoremstyle \@kernel@newtheoremstyle
  \let \theoremstyle    \@kernel@theoremstyle
  \let \proof           \@kernel@proof
  \let \endproof        \@kernel@endproof
%    \end{macrocode}
%    
%    
%    
%    The amsart, amsbook and amsproc classes do not use \cs{@author}
%    to store the author list but a command \cs{authors}. To be able
%    to nevertheless use the authors in the
%    xmp-metadata we map \cs{@author} to this new command.
%
%    The authors are set with a trivlist, this leads to faulty spacing
%    and wrong tagging.  This is not yet handled here, but an example
%    how to correct this is in the test-amsart-title test.
%    \begin{macrocode}
\def\@author{\authors}
%    \end{macrocode}
%    
%
%
%    In these classes the abstract is stored in a \cs{vbox}, as it
%    ends with a list an explicit \cs{par} is needed.
% \changes{v0.85i}{2025/01/26}{Add missing \cs{par} to abstract env (gh/1641)}
%    \begin{macrocode}
\renewenvironment{abstract}{%
    \ifx\maketitle\relax
      \ClassWarning{\@classname}{Abstract~ should~ precede~
        \protect\maketitle\space in~ AMS~ document~ classes;~ reported}%
    \fi
    \global\setbox\abstractbox=\vtop \bgroup
      \normalfont\Small
      \list{}{\labelwidth\z@
        \leftmargin3pc \rightmargin\leftmargin
        \listparindent\normalparindent \itemindent\z@
        \parsep\z@ \@plus\p@
        \let\fullwidthdisplay\relax
      }%
      \item[\hskip\labelsep\scshape\abstractname.]%
  }{%
    \endlist
    \par              % <--- added
    \egroup
    \ifx\@setabstract\relax \@setabstracta \fi
  }
%    \end{macrocode}
%
%
% \changes{v0.85w}{2026/05/21}{Use new \cs{newtheoremstyle} with AMS classes}
%
%    In the ams classes's \cs{newtheoremstyle} has different defaults
%    compared to the standalone \pkg{amsthm} package. Therefore the
%    classes have their own implementation of the command that we need
%    to overwrite as well.
%
%    \begin{macrocode}
\tl_set:Nn \newtheoremstyle@vspace@default {
  .5\baselineskip \@plus  .2\baselineskip \@minus .2\baselineskip
}
%    \end{macrocode}
%
%    The above takes care of newly defined theoremstyles, but the
%    default ones are already defined in the class so we have to
%    adjust their settings directly.
% \changes{0.86h}{2026-10-01}{Provide correct theorem-like defaults
%    for AMS classes (tagging/1632)}
%    \begin{macrocode}
\EditInstance{block}{thm-plain-1}
  { begin-vspace =  \newtheoremstyle@vspace@default }
\DeclareInstanceCopy{block}{thm-plain-2}{thm-plain-1}
%    \end{macrocode}
%
%    \begin{macrocode}
\EditInstance{block}{thm-remark-1}
  { begin-vspace =  \newtheoremstyle@vspace@default }
\DeclareInstanceCopy{block}{thm-remark-2}{thm-remark-1}
%    \end{macrocode}
%
%    \begin{macrocode}
\EditInstance{block}{thm-definition-1}
  { begin-vspace =  \newtheoremstyle@vspace@default }
\DeclareInstanceCopy{block}{thm-definition-2}{thm-definition-1}
%    \end{macrocode}
%
%    Beside the spacing the thmstyles also differ from the default
%    (but not for \texttt{amsart.cls}):
%    \begin{macrocode}
%<*amsbook,amsproc>
\EditInstance{thmstyle}{plain}
  { before-hspace =  \parindent , caption-decls = \scshape }
\EditInstance{thmstyle}{remark}
  { before-hspace =  \parindent , caption-decls = \scshape }
\EditInstance{thmstyle}{definition}
  { before-hspace =  \parindent , caption-decls = \scshape }
%</amsbook,amsproc>
%    \end{macrocode}
%
%
%
%
% \subsubsection{Headings}
%
% \changes{0.85r}{2026-01-06}
%      {Add tagging support for headings in ams-classes, tagging issue \#970}
% \changes{v0.85u}{2026-04-24}{Adapt keys to changes in sec-template.}  
% \changes{0.85y}{2026-07-11}{Provide proper heading instances for all
%    ams classes (tagging/1477)}
%
%    The classes redefine \cs{@startsection} and define their own
%    heading commands which are not tagging compatible.
%    This code is therefore disabled and replaced by standard
%    definitions that process the heading arguments and call a
%    suitable template instance. The top-level definitions are
%    identical for all classes (only the heading instances then
%    differ).
%
%    \begin{macrocode}
\DeclareDocumentCommand \part {s ={shorttitle}o m}
    { \ParseLaTeXeHeading {part} {#1} {#2} {#3} }
%    \end{macrocode}
%    
%    Chapters only exist in \cls{amsbook} and their top-level
%    definition is also slightly special as we need a different
%    heading instance for numbered and unnumbered chapters.
%    \begin{macrocode}
%<*amsbook>
\DeclareDocumentCommand \chapter {s ={shorttitle}O{} m}
  {
    \IfBooleanTF{#1}
      { \ParseLaTeXeHeading {chapter*} {#1} {#2} {#3} }
      { \ParseLaTeXeHeading {chapter}  {#1} {#2} {#3} }
  }
%</amsbook>
%    \end{macrocode}
%
%    \begin{macrocode}
\DeclareDocumentCommand \section {s ={shorttitle}o m}
  { \ParseLaTeXeHeading {section} {#1} {#2} {#3} }
%    \end{macrocode}
%
%    The \cs{specialsection} command is a variation of the
%    \texttt{section} layout so has its own heading instance.
%    \begin{macrocode}
\DeclareDocumentCommand \specialsection {s ={shorttitle}o m}
  { \ParseLaTeXeHeading {specialsection} {#1} {#2} {#3} }
%    \end{macrocode}
%
%    \begin{macrocode}
\DeclareDocumentCommand \subsection {s ={shorttitle}o m}
  { \ParseLaTeXeHeading {subsection} {#1} {#2} {#3} }
%    \end{macrocode}
%
%
%    \begin{macrocode}
\DeclareDocumentCommand \subsubsection {s ={shorttitle}o m}
  { \ParseLaTeXeHeading {subsubsection} {#1} {#2} {#3} }
%    \end{macrocode}
%
%
%    \begin{macrocode}
\DeclareDocumentCommand \paragraph {s ={shorttitle}o m}
  { \ParseLaTeXeHeading {paragraph} {#1} {#2} {#3} }
%    \end{macrocode}
%
%
%    \begin{macrocode}
\DeclareDocumentCommand \subparagraph {s ={shorttitle}o m}
  { \ParseLaTeXeHeading {subparagraph} {#1} {#2} {#3} }
%    \end{macrocode}
%
%
%
%    The heading template instances have some subtle differences in the
%    different AMS classes. We therefore set all of them up by
%    document class, even though some of the code is the same.
%    
%    \begin{macrocode}
%<*amsbook>
%    \end{macrocode}
%    
%    
%    \begin{macrocode}
\DeclareInstance{heading}{part}{display}
  {
    , name                  = part
    , level                 = -1
    , placement             = page
    , placement-start-code  =  \cleardoublepage \thispagestyle{empty}
                               \null \vfil \markboth{}{}
    , placement-end-code    = \vfil \vfil \newpage \thispagestyle{empty}
    , mark-cmd              = \partmark {#1}
    , heading-decls         = \centering\fontsize{\@xviipt}{22}\bfseries
    , headformat-instance   = part
    , text                  = \partname
    , number-format         = #1
    , title-decls           = \fontsize{\@xxpt}{25}\bfseries
  }
%    \end{macrocode}
%
%    Current heading templates aren't flexible enough and do not
%    properly support altering the layout for unnumbered headings
%    compared to their numbered counterparts. For this reason we have
%    two heading instances, one for \cs{chapter} and one for \cs{chapter*}.
%
%    \begin{macrocode}
\DeclareInstance{heading}{chapter}{display}
  {
    , name                 = chapter
    , level                = 0
    , mark-cmd             = \chaptermark {#1}
    , para-indent          = true
    , placement            = top
    , after-penalty-vspace = 42pt  % 32pt plus \topskip
    , after-vspace         = 22pt
    , heading-decls        = \normalsize\mdseries\centering
    , headformat-instance  = chapter
    , text                 = \MakeUppercase{\chaptername}
    , number-format        = #1
    , title-decls          = \fontsize{\@xivpt}{18} \bfseries
    , contents-extra       = \addtocontents{lof}{\protect\addvspace{10\p@}}
                             \addtocontents{lot}{\protect\addvspace{10\p@}}
  }
%    \end{macrocode}
%
%    \begin{macrocode}
\DeclareInstanceCopy{heading}{chapter*}{chapter}
\EditInstance{heading}{chapter*}{ after-penalty-vspace = 72pt }  % 62pt + \topskip
%    \end{macrocode}
%
%    \begin{macrocode}
\DeclareInstance{headformat}{chapter}{display}
  {
    , heading-indent = 0pt
    , separator-b    = \par \nobreak \vspace{18pt}
  }
%    \end{macrocode}
%    
%    
%    \begin{macrocode}
\DeclareInstance{heading}{section}{display}
  {
    , name                = section
    , level               = 1
    , mark-cmd            = \sectionmark{#1}
    , para-indent         = true
    , before-vspace       = 0.7\linespacing plus \linespacing
    , after-vspace        = 0.5\linespacing
    , heading-decls       = \normalfont \bfseries \centering
    , headformat-instance = section
    , number-format       = #1.
    , number-decls        = \upshape
  }
\DeclareInstance{headformat}{section}{hang}
  {
    separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%
%    A \cs{specialsection} is like a \cs{section} with two changes in
%    the parameter settings.  
%    \begin{macrocode}
\DeclareInstanceCopy{heading}{specialsection}{section}
\EditInstance{heading}{specialsection}
   {
     , before-vspace = 2\linespacing plus \linespacing
     , heading-decls = \large \scshape \centering
   }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{subsection}{runin}
  {
    , name                = subsection
    , level               = 2
    , mark-cmd            = \subsectionmark{#1}
    , before-vspace       = 0.5\linespacing plus 0.7\linespacing
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont \bfseries
    , headformat-instance = subsection
    , number-format       = #1.
    , number-decls        = \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{subsection}{runin}
  {
    , separator-b    = \hspace{0.5em}
    , heading-indent = \normalparindent
  }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{subsubsection}{runin}
  {
    , name                = subsubsection
    , level               = 3
    , mark-cmd            = \subsubsectionmark{#1}
    , before-vspace       = 0pt
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont \itshape
    , headformat-instance = subsubsection
    , number-format       = #1.
    , number-decls        = \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{subsubsection}{runin}
  {
    , separator-b    = \hspace{0.5em}
    , heading-indent = \normalparindent
  }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{paragraph}{runin}
  {
    , name                = paragraph
    , level               = 4
    , mark-cmd            = \paragraphmark{#1}
    , before-vspace       = 0pt
    , after-hspace        = \fontdimen2 \font
    , heading-decls       = \normalfont
    , headformat-instance = paragraph
    , number-format       = #1.
    , number-decls        = \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{paragraph}{runin}
  {
    , separator-b    = \hspace{0.5em}
    , heading-indent = \normalparindent
  }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{subparagraph}{runin}
  {
    , name                = subparagraph
    , level               = 5
    , mark-cmd            = \subparagraphmark{#1}
    , before-vspace       = 0pt
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont
    , headformat-instance = subparagraph
    , number-format       = #1.
    , number-decls        = \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{subparagraph}{runin}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%
%    The running header setup from amsbook doesn't correctly function
%    and needs adjustments. For now we provide some simple
%    redefinitions which do not necessarily produce exactly the same results.  
%    \begin{macrocode}
\def\partmark#1{%
  \markboth{}{}
}
\def\chaptermark#1{%
  \markboth {\MakeUppercase{%
      \ifnum \c@secnumdepth >\m@ne
        \thechapter. \ %
      \fi
      #1}}{}
}
\def\sectionmark#1{%
      \markright {\MakeUppercase{%
        \ifnum \c@secnumdepth >\z@
          \thesection. \ %
        \fi
        #1}}
}
%    \end{macrocode}
%
%    \begin{macrocode}
%</amsbook>
%    \end{macrocode}
%    
%    
%    
%    
%    
%    
%    \begin{macrocode}
%<*amsart>
%    \end{macrocode}
%
%    The use of \cs{mdseries} in several of the instances is really
%    odd (and not done in \cls{amsbook} or \cls{amsproc}) but it is
%    what the current class generates as a layout, so we keep it that
%    way.
%  
%    \begin{macrocode}
\DeclareInstance{heading}{part}{display}
  {
    , name                = part
    , level               = -1                  % -1 or 0 ?
    , mark-cmd            = \partmark{#1}
    , para-indent         = true
    , before-vspace       = \linespacing plus \linespacing
    , after-vspace        = 0.5 \linespacing
    , heading-decls       = \normalfont \bfseries \raggedright
    , headformat-instance = part
    , text                = \partname
    , number-format       = \theheading .
    , number-decls        = \mdseries \upshape  % proc: has just \upshape
  }
\DeclareInstance{headformat}{part}{hang}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%
%    \begin{macrocode}
\DeclareInstance{heading}{section}{display}
  {
    , name                = section
    , level               = 1
    , mark-cmd            = \sectionmark{#1}
    , para-indent         = true
    , before-vspace       = 0.7\linespacing plus \linespacing
    , after-vspace        = 0.5\linespacing
    , heading-decls       = \normalfont \scshape \centering
    , headformat-instance = section
    , number-format       = \theheading .
    , number-decls        = \mdseries \upshape
  }
\DeclareInstance{headformat}{section}{hang}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%    
%    The \cs{specialsection} command is a variation of the
%    \texttt{section} layout.
%
%    \begin{macrocode}
\DeclareInstanceCopy{heading}{specialsection}{section}
\EditInstance{heading}{specialsection}
   {
     , before-vspace = \linespacing plus \linespacing
     , heading-decls = \normalfont \centering
   }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{subsection}{runin}
  {
    , name                = subsection
    , level               = 2
    , mark-cmd            = \subsectionmark{#1}
    , before-vspace       = 0.5\linespacing plus 0.7\linespacing
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont \bfseries
    , headformat-instance = subsection
    , number-format       = \theheading .
    , number-decls        = \mdseries \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{subsection}{runin}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{subsubsection}{runin}
  {
    , name                = subsubsection
    , level               = 3
    , mark-cmd            = \subsubsectionmark{#1}
    , before-vspace       = 0.5\linespacing plus 0.7\linespacing
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont \itshape
    , headformat-instance = subsubsection
    , number-format       = \theheading .
    , number-decls        = \mdseries \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{subsubsection}{runin}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{paragraph}{runin}
  {
    , name                = paragraph
    , level               = 4
    , mark-cmd            = \paragraphmark{#1}
    , before-vspace       = 0pt
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont
    , headformat-instance = paragraph
    , number-format       = \theheading .
    , number-decls        = \mdseries \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{paragraph}{runin}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{subparagraph}{runin}
  {
    , name                = subparagraph
    , level               = 5
    , mark-cmd            = \subparagraphmark{#1}
    , before-vspace       = 0pt
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont
    , headformat-instance = subparagraph
    , number-format       = \theheading .
    , number-decls        = \mdseries \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{subparagraph}{runin}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%
%    \begin{macrocode}
%</amsart>
%    \end{macrocode}
%
%    
%    
%    
%    
%    \begin{macrocode}
%<*amsproc>
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{part}{display}
  {
    , name                = part
    , level               = -1                  % -1 or 0 ?
    , mark-cmd            = \partmark{#1}
    , para-indent         = true
    , before-vspace       = \linespacing plus \linespacing
    , after-vspace        = 0.5 \linespacing
    , heading-decls       = \normalfont \bfseries \raggedright
    , headformat-instance = part
    , text                = \partname
    , number-format       = \theheading .
    , number-decls        = \upshape
  }
\DeclareInstance{headformat}{part}{hang}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%
%    \begin{macrocode}
\DeclareInstance{heading}{section}{display}
  {
    , name                = section
    , level               = 1
    , mark-cmd            = \sectionmark{#1}
    , para-indent         = true
    , before-vspace       = 0.7\linespacing plus \linespacing
    , after-vspace        = 0.5\linespacing
    , heading-decls       = \normalfont \bfseries \centering
    , headformat-instance = section
    , number-format       = \theheading .
    , number-decls        = \upshape
  }
\DeclareInstance{headformat}{section}{hang}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%    
%    The \cs{specialsection} command is a variation of the
%    \texttt{section} layout.
%    \begin{macrocode}
\DeclareInstanceCopy{heading}{specialsection}{section}
\EditInstance{heading}{specialsection}
   {
     , before-vspace = \linespacing plus \linespacing
     , heading-decls = \large \scshape \centering
   }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{subsection}{runin}
  {
    , name                = subsection
    , level               = 2
    , mark-cmd            = \subsectionmark{#1}
    , before-vspace       = 0.5\linespacing plus 0.7\linespacing
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont \bfseries
    , headformat-instance = subsection
    , number-format       = \theheading .
    , number-decls        = \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{subsection}{runin}
  {
    , separator-b    = \hspace{0.5em}
    , heading-indent = \normalparindent
  }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{subsubsection}{runin}
  {
    , name                = subsubsection
    , level               = 3
    , mark-cmd            = \subsubsectionmark{#1}
    , before-vspace       = 0.5\linespacing plus 0.7\linespacing
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont \itshape
    , headformat-instance = subsubsection
    , number-format       = \theheading .
    , number-decls        =  \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{subsubsection}{runin}
  {
    , separator-b    = \hspace{0.5em}
    , heading-indent = \normalparindent
  }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{paragraph}{runin}
  {
    , name                = paragraph
    , level               = 4
    , mark-cmd            = \paragraphmark{#1}
    , before-vspace       = 0pt
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont
    , headformat-instance = paragraph
    , number-format       = \theheading .
    , number-decls        = \upshape
    , title-format        = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{paragraph}{runin}
  {
    , separator-b = \hspace{0.5em}
    , heading-indent   = \normalparindent
  }
%    \end{macrocode}
%    
%    \begin{macrocode}
\DeclareInstance{heading}{subparagraph}{runin}
  {
    , name                = subparagraph
    , level               = 5
    , mark-cmd            = \subparagraphmark{#1}
    , before-vspace       = 0pt
    , after-hspace        = \fontdimen2\font
    , heading-decls       = \normalfont
    , headformat-instance = subparagraph
    , number-format       = \theheading .
    , number-decls        = \upshape
    , title-format = #1 \AddPunct{.}
  }
\DeclareInstance{headformat}{subparagraph}{runin}
  {
    , separator-b = \hspace{0.5em}
  }
%    \end{macrocode}
%
%    \begin{macrocode}
%</amsproc>
%    \end{macrocode}
%
%  
%  
%  
%    \begin{macrocode}
%<*amsbook>
%    \end{macrocode}
%
%    The AMS classes do a lot of low-level overwrites to macros
%    building out the table of contents structures. \cs{@starttoc}
%    being one example which is partially fixed here. This isn't the
%    full fix: various \cs{l@...} macros also need changes, but that
%    has to wait for another day \ldots\ for now we only make sure
%    that the code doesn't break badly, but they layout is not
%    matching what the class normally produces!
%    \begin{macrocode}
\def\@starttoc#1#2{%
  \begingroup
  \setTrue{#1}%
  \ifx\contentsname#2%
    \chapter[unnumbered,toc=]{\contentsname}%
  \else
    \chapter[=,unnumbered]{#2}%
  \fi
  \typeout{#2}%
  \makeatletter
  \@input{\jobname.#1}%
  \if@filesw
    \@xp\newwrite\csname tf@#1\endcsname
    \immediate\@xp\openout\csname tf@#1\endcsname \jobname.#1\relax
  \fi
  \global\@nobreakfalse
  \endgroup
  \newpage
  }
%    \end{macrocode}
%
%    \begin{macrocode}
\AddToHook{begindocument}{
  \@namedef{r@tocindent-1}{1em}
  \@namedef{r@tocindent0}{1em}
  \@namedef{r@tocindent1}{1em}
}
%    \end{macrocode}
%    
%
%    \begin{macrocode}
%</amsbook>
%    \end{macrocode}
%    
%    \begin{macrocode}
\ExplSyntaxOff
%</amscls>
%<*package>
%    \end{macrocode}
%
%
%    \begin{macrocode}
\ExplSyntaxOff
%    \end{macrocode}
%
%
%
%
%
%  \subsection{fncychap}
%
%    First aid for \pkg{fncychap} is kept in a separate file.
%    \begin{macrocode}
\AddToHook{package/fncychap/after}[latex-lab-firstaid]{\input{latex-lab-firstaid-fncychap.ltx}}
%    \end{macrocode}
%
%
%    \begin{macrocode}
%</package>
%<*fncychap>
%    \end{macrocode}
%
%
%    \begin{macrocode}
\ExplSyntaxOn
%    \end{macrocode}
%
%    The \pkg{fncychap} package has its own way of offering
%    customizations including arbitrary rewrites for the commands
%    \cs{DOCH}, \cs{DOTI}, and \cs{DOTIS}. In order to support
%    customizations in existing documents (defining chapter layout
%    variations in this fashion) we define a headformat in which the
%    three commands are simply called to typeset the heading, i.e.,
%    the template doesn't offer any customizations through
%    keys---everything is done through the interfaces of
%    \pkg{fncychap} as before.
%
%    For the same reason most of the keys of the chapter instance are
%    nonfunctional, i.e., they exist but aren't used with a few
%    exceptions. After all, the purpose here is to make \pkg{fncychap}
%    tagging compatible and not to extend its functionality or offer
%    additional customization possibilities.
%
%    The two values in the heading chapter instance that we need to
%    alter are \key{after-vspace} and set it to zero (because this is
%    handled inside \cs{DOTI} or \cs{DOTIS}) and
%    \key{headformat-instance} as we want to call our own instance
%    suitable to deal with the customization possibilities offerered
%    by \pkg{fncychap}. Thus we edit the default \insttype{heading}
%    \instname{chapter} instance in the following way.
%
%    \begin{macrocode}
\EditInstance{heading}{chapter}{
    after-vspace        = 0pt
  , headformat-instance = fncychap
}
%    \end{macrocode}
%
%    This means  we have to declare a new template \instname{fncychap}
%    of type \insttype{headformat} (with no keys as explained above):
%    \begin{macrocode}
\DeclareTemplateInterface{headformat}{fncychap}{6}{}
%    \end{macrocode}
%    
%
%    The code for this template is fairly simple.
%    \begin{macrocode}
\DeclareTemplateCode{headformat}{fncychap}{6}{}
{
%    \end{macrocode}
%    Output some debugging info at the start.
%    \begin{macrocode}
  \__head_show_arguments:nnnnnn {#1}{#2}{#3}{#4}{#5}{#6}
%    \end{macrocode}
%    Everything else happens in a group to keep changes local.
%    \begin{macrocode}
  \group_begin:
%    \end{macrocode}
%    First, make a link target (with slight difference depending on
%    whether or not the chapter is numbered).
%    \begin{macrocode}
    \bool_if:NTF \l__head_unnumbered_bool
      { \MakeLinkTarget [ \l__head_name_tl ] {}   }
      { \MakeLinkTarget { \l__head_name_tl }      }
%    \end{macrocode}
%    Next follow some default paragraph settings that may or may not
%    be overwritten by declarations for a specific chapter layout
%    from the package.
%    \begin{macrocode}
    \parindent 0pt
    \raggedright
    \interlinepenalty 10000
    \normalfont
%    \end{macrocode}
%    Then we have a few tagging socket settings for \cs{parbox} or
%    \env{minipage} environments, because some heading designs use
%    \cs{parbox}es and they need the special settings in the context
%    of a heading to make the tagging work.
%    \begin{macrocode}
    \AssignTaggingSocketPlug{parbox/before}{heading}
    \AssignTaggingSocketPlug{minipage/before}{heading}
    \AssignTaggingSocketPlug{para/restore}{noop}
%    \end{macrocode}
%    Finally, we have the bare heading design as used in the
%    package. When the heading is numbered then \cs{DOCH} is
%    responsible to place the fixed heading text (e.g., Chapter) and the
%    chapter number.
%
%    We start by calling \cs{fncychap@setup@thechapter} which gives
%    \cs{thechapter} a special definition while the heading is typeset
%    (since we are in a group here this is reverted immmediately after).
%    \begin{macrocode}
    \fncychap@setup@thechapter
%    \end{macrocode}
%    
%    \begin{macrocode}
    \bool_if:NF \l__head_unnumbered_bool
      { \DOCH }
%    \end{macrocode}
%    If we are in \enquote{main matter} then \cs{DOTI} typesets the
%    chapter title, otherwise \cs{DOTIS} is used to typeset the
%    chapter title.
%    \begin{macrocode}
    \legacy_if:nTF { @mainmatter }
      { \DOTI{#4}  }
      { \DOTIS{#4} }
%    \end{macrocode}
%    We finish off with a \cs{par} to ensure that we are back in
%    vertical mode and then close the group.
%    \begin{macrocode}
    \par
  \group_end:
}
%    \end{macrocode}
%    
%
%    We use this template to create the \insttype{headformat} instance
%    used in the \insttype{heading} instance. Since the template has no
%    keys this is a trivial declaration:
%    \begin{macrocode}
\DeclareInstance{headformat}{fncychap}{fncychap}{}
%    \end{macrocode}
%    
%
%
%    To put a \struct{heading-number} structure around the number
%    without really knowing how the heading layout is done, we hook
%    into \cs{thechapter}. This redefinition only happens within the
%    \texttt{headformat} instance when we typeset the
%    heading. Elsewhere \cs{thechapter} retains its usual definition,
%    e.g., when used inside the document or in a running header or toc
%    entry.
%
% \changes{v0.86k}{2026-10-25}{Pass number not an unexpanded
%    \cs{thechapter} to toc (tagging/1668)}
%    \begin{macrocode}
\def\fncychap@setup@thechapter{
  \def\thechapter{\thespecialchapter{\@arabic\c@chapter}}
}  
%    \end{macrocode}
%    
%    \begin{macrocode}
\def\appendix{\par
  \setcounter{chapter}{0}
  \setcounter{section}{0}
  \gdef\@chapapp{\appendixname}
  \gdef\thechapter{\@Alph\c@chapter}
%    \end{macrocode}
%    Add the special setup for using in the \texttt{headformat}
%    template above.
%    \begin{macrocode}
  \gdef\fncychap@setup@thechapter{
    \def\thechapter{\thespecialchapter{\@Alph\c@chapter}}
  }  
}
%    \end{macrocode}
%    
%
%    
%
%    The \cs{thespecialchapter} ensures that hmode is started and then
%    normally generates a \struct{heading-number} structure but only
%    if we aren't already in an \struct{Lbl}. It then typesets the
%    current number.
% \changes{v0.86k}{2026-10-25}{Pass number not an unexpanded
%    \cs{thechapter} to toc (tagging/1668)}
%    \begin{macrocode}
\protected\def\thespecialchapter#1{
  \leavevmode
  \tag_if_in:nTF{Lbl}
    { #1 }
    {
      \UseTaggingSocket{inline/begin}{tag=heading-number}
      #1 
      \UseTaggingSocket{inline/end}
    }
}
%    \end{macrocode}
%    
%
%
%  \begin{macro}{\mghrulefill}
%    
%    This here is a special rule definition from \pkg{fncychap} that
%    we overwrite to add the necessary tagging support.
%    \begin{macrocode}
\protected\def\mghrulefill#1{\leavevmode
  \UseTaggingSocket{rule}{}{
    \leaders\hrule\@height #1\hfill\kern\z@
  }
}
%    \end{macrocode}
%  \end{macro}
%
%
%    
%    \begin{macrocode}
\ExplSyntaxOff
%    \end{macrocode}
%    
%    \begin{macrocode}
%</fncychap>
%<*package>
%    \end{macrocode}
%
%
%
%
%
%
%
% \subsection{cleveref}
%
% The cleveref package redefines \cs{@makefntext} and this means that the patches in
% the new footnote code fails. We use a hook instead.
% \changes{v0.85h}{2024/10/16}{Remove redefinition of refstepcounter. It no longer uses
% the hook.}
%    \begin{macrocode}
\AddToHook{package/cleveref/after}
 {
   \let\@makefntext\cref@old@makefntext
   \AddToHook{cmd/@makefntext/before}{%
    \cref@constructprefix{footnote}{\cref@result}%
    \protected@edef\cref@currentlabel{%
     [footnote][\arabic{footnote}][\cref@result]%
    \p@footnote\@thefnmark}}
 }
%    \end{macrocode}
%
% \subsection{booktabs}
% In some cases booktabs inserts a
% \cs{multispan} into the table (through the commands \cs{@cmidruleb}
% and \cs{@cmidrulea} and this then errors
% with the tagging code.
% This affects both tabular and longtable
% (but longtable more as booktabs handles lines in longtable differently).
% See also issue \url{https://github.com/latex3/tagging-project/issues/69}
%
% \changes{0.85u}{2026-04-24}{Use tagging sockets}
%    \begin{macrocode}
\ExplSyntaxOn
\AddToHook{package/booktabs/after}
 {
  \def\@cmidrulea{
   \multispan\@cmidla
   &\multispan\@cmidlb
   \unskip\hskip\cmrkern@l
  {
   \UseTaggingSocket{tbl/leaders/begin}
   \CT@arc@\leaders\hrule \@height\@thisrulewidth\hfill\kern\z@}
   \hskip\cmrkern@r
   \UseTaggingSocket{tbl/leaders/end}
   \tbl_gdecr_row_count:
   \cr}

  \def\@cmidruleb{%
    \multispan\@cmidlb
    \unskip\hskip \cmrkern@l%
   {
    \UseTaggingSocket{tbl/leaders/begin}
    \CT@arc@\leaders\hrule \@height\@thisrulewidth\hfill\kern\z@}
    \hskip\cmrkern@r
    \UseTaggingSocket{tbl/leaders/end}
    \tbl_gdecr_row_count:
    \cr}
  }
\ExplSyntaxOff
%    \end{macrocode}
%
%
% \subsection{fancyvrb}
% The firstaid adds first partial tagging support to the environments
% of fancyvrb (inline verbatim is untested).
% This supports then also packages like minted which internally uses fancyvrb
% and classes like l3doc (where currently the verbatim environment based on fancyvrb
% is overwritten by the block code).
% The environments are surrounded by a \texttt{verbatim} structure,
% every line by a \texttt{codeline}
% structure. Line numbers are tagged as \texttt{Lbl}, inside of the
% \texttt{codeline} structure. The frame lines are marked as artifact.
%
% \begin{macro}[no-user-doc]{\FV@LeaveVMode}
% If we are in vmode we have to open a semantic-para structure, if we are
% in hmode we have to set para mode to flattened before the fancyvrb code
% issues the\cs{par}. The closing of the semantic-para structure is handled by the
% doendpe code in the block code.
% \changes{0.85u}{2026-04-24}{Use tagging sockets}
%    \begin{macrocode}
\ExplSyntaxOn
\AddToHook{package/fancyvrb/after}
{
    \def\FV@LeaveVMode{%
      \if@noskipsec
        \leavevmode
      \else
        \if@FV@ResetMargins\if@inlabel\leavevmode\fi\fi
      \fi
      \ifvmode
        \@noparlisttrue
        \UseTaggingSocket{para/semantic/begin}{}
      \else
        \tagpdfsetup{para/flattened=true}
        \@noparlistfalse
        \unskip\par
      \fi
      }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}[no-user-doc]{\FV@List}
% At the begin of the list code we have to tag the frame as artifact
% and start the \texttt{verbatim} structure
%    \begin{macrocode}
    \def\FV@List#1{%
      \begingroup
      \FV@UseKeyValues
      \FV@LeaveVMode
      \if@inlabel\else\setbox\@labels=\box\voidb@x\fi
      \FV@ListNesting{#1}%
      \FV@ListParameterHook
      \FV@ListVSpace
      \FV@SetLineWidth
      \FV@InterLinePenalty
      \let\FV@ProcessLine\FV@ListProcessLine@i
      \FV@CatCodes
      \FV@FormattingPrep
      \FV@ObeyTabsInit
      \cs_if_exist:NT \FV@BeginListFrame
        {
         \UseTaggingSocket{mc}{artifact}{\FV@BeginListFrame}
        }
      \UseTaggingSocket{struct/begin}{tag=\UseStructureName{block/verbatim}}
      }
%    \end{macrocode}
% \end{macro}
% \begin{macro}[no-user-doc]{\FV@EndList}
% At the end of the list code we close the \texttt{verbatim} structure and
% tag the frame as artifact.
%    \begin{macrocode}
    \def\FV@EndList{%
      \FV@ListProcessLastLine
      \UseTaggingSocket{struct/end}
      \cs_if_exist:NT \FV@EndListFrame
        {
         \UseTaggingSocket{mc}{artifact}{\FV@EndListFrame}
        }
      \@endparenv
      \endgroup
      \@endpetrue
      }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}[no-user-doc]{\FV@ListProcessLine}
% At last the tagging of the code lines. Here we have to tag also
% numbers and frame parts if they exist.
%    \begin{macrocode}
    \def\FV@ListProcessLine#1{%
      \hbox to \hsize{%
        \kern\leftmargin
        \hbox to \linewidth{%
         \UseTaggingSocket{struct/begin}{tag=\UseStructureName{block/verbatim/codeline}}
          \cs_if_exist:NT \FV@LeftListNumber
           {
             \UseTaggingSocket{struct-mc}{tag=\UseStructureName{block/verbatim/linenumber}}
              {
                \FV@LeftListNumber
              }
           }
          \cs_if_exist:NT \FV@LeftListFrame
           {
             \UseTaggingSocket{mc}{artifact}{\FV@LeftListFrame}
           }
          \UseTaggingSocket{mc}{}{\FancyVerbFormatLine{#1}}%
          \UseTaggingSocket{struct/end}\hss
          \cs_if_exist:NT \FV@RightListFrame
           {
             \UseTaggingSocket{mc}{artifact}{\FV@RightListFrame}
           }
          \cs_if_exist:NT \FV@RightListNumber
           {
             \UseTaggingSocket{struct-mc}{tag=\UseStructureName{block/verbatim/linenumber}}
               {
                 \FV@RightListNumber
               }
           }
          }
          \hss}}
  }
\ExplSyntaxOff
%    \end{macrocode}
% \end{macro}
%
% \subsection{The \pkg{float} package first aid}
%
% The float package has a number of incompatibilites:
% \begin{itemize}
% \item Restyling floats with \cs{restylefloat} breaks the tagging tagging support.
% \item New float types created with \cs{newfloat} are not properly tagged (tagging issue 890)
% \item Non-floating floats using the \texttt{H} placement are not properly tagged.
% \end{itemize}
% The following firstaid addresses these problems.
% A flaw is that if the H-float is inside a paragraph and followed
% by text there the text is tagged as a new semantic-para structure. 
% 
% Because of this and other limitations the final solution may look noticeably different 
% including the used tagging sockets, etc.
% TODO
% 
% The firstaid for \pkg{float} is kept in a separate file.
%    \begin{macrocode}
\AddToHook{package/float/after}[latex-lab-firstaid]{\input{latex-lab-firstaid-float.ltx}}
%</package>
%    \end{macrocode}

%    \begin{macrocode}
%<*float>
\ProvidesFile{latex-lab-firstaid-float.ltx}
 [\ltlabfirstaiddate\space \ltlabfirstaidversion\space LaTeX-lab-firstaid: Tagging support for the float package]
%    \end{macrocode}
% Tagging sockets for the H-floats
%    \begin{macrocode}
\ExplSyntaxOn
\NewTaggingSocket{float/H/begin}{1}
\NewTaggingSocketPlug{float/H/begin}{default}
 {
   \mode_if_horizontal:T {\tag_mc_end_push: \tag_struct_end:}
   \tag_struct_begin:n {tag=\UseStructureName{float/#1}}
 }
\AssignTaggingSocketPlug{float/H/begin}{default}

\NewTaggingSocket{float/H/end}{0}
\NewTaggingSocketPlug{float/H/end}{default}
 {
    \tag_struct_end:
    \mode_if_horizontal:T
     {
       \tag_struct_begin:n {tag=\UseStructureName{para/textblock}}
       \tag_mc_begin_pop:n {}
     }
 }
\AssignTaggingSocketPlug{float/H/end}{default}
%    \end{macrocode}
% and here the redefinitions of the commands of \pkg{float}
% for the H-floats:
%    \begin{macrocode}
\def\@float@HH#1[H]{\UseTaggingSocket{float/H/begin}{#1}%
  \expandafter\let\csname end#1\endcsname\float@endH
  \let\@currbox\float@box
  \def\@captype{#1}\setbox\@floatcapt=\vbox{}%
  \expandafter\ifx\csname fst@#1\endcsname\relax
  \@flstylefalse\else\@flstyletrue\fi
  \setbox\@currbox\color@vbox\normalcolor
    \vbox\bgroup \hsize\columnwidth \@parboxrestore
     \@floatboxreset \@setnobreak
  \ignorespaces}
\renewcommand\float@endH{\@endfloatbox\UseTaggingSocket{float/H/end}
  \vskip\intextsep
  \if@flstyle\setbox\@currbox\float@makebox\columnwidth\fi
  \box\@currbox\vskip\intextsep\relax}  
\ExplSyntaxOff
%    \end{macrocode}
% Float defines two float styles which need to get tagging support.
% This here is the plain style which is also used for plaintop and boxed:
%    \begin{macrocode}
\renewcommand\floatc@plain[2]{%
  \setbox\@tempboxa\hbox{\measuring@true{\@fs@cfont #1:} #2}%
  \UseTaggingSocket{caption/begin}{\@current@float@struct}% 
  \ifdim\wd\@tempboxa>\hsize 
   \UseTaggingSocket{caption/label/begin}%
    {\@fs@cfont #1:}%
   \UseTaggingSocket{caption/label/end}%
%    \end{macrocode}
% The space is intentional!
%    \begin{macrocode}
  \UseTaggingSocket{para/begin} % 
     #2\par     
  \else
   \hbox to \hsize {\hfil
     \UseTaggingSocket{caption/label/begin}%
       {\@fs@cfont #1:}%
     \UseTaggingSocket{caption/label/end}% 
%    \end{macrocode}
% The space is intentional!
%    \begin{macrocode}       
     \UseTaggingSocket{para/begin} %
   #2%
   \UseTaggingSocket{para/end}\hfil}%
   \par
  \fi
%    \end{macrocode}
% The caption structure is not closed here, but in the \cs{float@caption}
% and \cs{float@ccon} commands.
%    \begin{macrocode}
  }
%    \end{macrocode}
% This adds tagging support to the ruled style:
%    \begin{macrocode}
\renewcommand\floatc@ruled[2]{%
  \UseTaggingSocket{caption/begin}{\@current@float@struct}%
  \UseTaggingSocket{caption/label/begin}%
   {\@fs@cfont #1}% 
  \UseTaggingSocket{caption/label/end}% 
%    \end{macrocode}
% The space is intentional!
%    \begin{macrocode}    
  \UseTaggingSocket{para/begin} #2\par %
%    \end{macrocode}
% The caption is not closed here but in the \cs{float@caption}
% and \cs{float@ccon} commands.
%    \begin{macrocode}
 }
%    \end{macrocode}
% The \pkg{float} package adds a final optional argument to caption which can be used to
% add text (this is not documented).
% We add the \texttt{caption/end} socket after this test, so that it is part of the 
% caption.  We also force a \cs{par} to avoid nested mc with pdflatex.
%    \begin{macrocode}
\long\def\float@caption#1[#2]#3{\par\addcontentsline{\@nameuse{ext@#1}}{#1}%
   {\protect\numberline{\@nameuse{the#1}}{\ignorespaces #2}}
  \global\setbox\@floatcapt\vbox\bgroup\@parboxrestore
    \normalsize\@fs@capt{\@nameuse{fnum@#1}}{\ignorespaces #3}%
    \@ifnextchar[{\float@ccon}{\UseTaggingSocket{caption/end}\egroup}%]
      }
\long\def\float@ccon[#1]{#1\par\UseTaggingSocket{caption/end}\egroup}
%    \end{macrocode}
% If a new float is declared it should setup the container. We also adapt
% the tag of this container:
%    \begin{macrocode}
\renewcommand\newfloat[3]{\@namedef{ext@#1}{#3}
  \tagpdfsetup{float/new=#1,role/new-tag=#1-floats/Sect}%
  \AssignStructureRole{float/#1s}{#1-floats}%
  \let\float@do=\relax
  \xdef\@tempa{\noexpand\float@exts{\the\float@exts \float@do{#3}}}%
  \@tempa
  \floatplacement{#1}{#2}%
  \@ifundefined{fname@#1}{\floatname{#1}{#1}}{}
  \expandafter\edef\csname ftype@#1\endcsname{\value{float@type}}%
  \addtocounter{float@type}{\value{float@type}}
  \restylefloat{#1}%
  \expandafter\edef\csname fnum@#1\endcsname%
    {\expandafter\noexpand\csname fname@#1\endcsname{}
       \expandafter\noexpand\csname the#1\endcsname}
  \@ifnextchar[{\float@newx{#1}}%]
    {\@ifundefined{c@#1}{\newcounter{#1}\@namedef{the#1}{\arabic{#1}}}%
      {}}}
%</float>
%    \end{macrocode}
%
% \subsection{The \pkg{apacite} firstaid}
% The apacite package redefines \cs{@lbibitem} and removes the arguments.
% This means that the patching with a generic hook with arguments fails. So we readd the argument.
% \changes{0.85x}{2026-06-08}{Correct braces around argument.}
%    \begin{macrocode}
%<*package>
\AddToHook{package/apacite/after} 
  {\if@APAC@natbib@apa\def\@lbibitem[#1]#2{\NAT@swatrue\orig@nat@@@@lbibitem[#1]{#2}}\fi}
%    \end{macrocode}
%    \begin{macrocode}
%</package>
%    \end{macrocode}