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diff --git a/macros/latex/base/lttagging.dtx b/macros/latex/base/lttagging.dtx
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+% \iffalse meta-comment
+%
+% Copyright (C) 2023-2024
+% The LaTeX Project and any individual authors listed elsewhere
+% in this file.
+%
+% This file is part of the LaTeX base system.
+% -------------------------------------------
+%
+% It may be distributed and/or modified under the
+% conditions of the LaTeX Project Public License, either version 1.3c
+% of this license or (at your option) any later version.
+% The latest version of this license is in
+%    https://www.latex-project.org/lppl.txt
+% and version 1.3c or later is part of all distributions of LaTeX
+% version 2008 or later.
+%
+% This file has the LPPL maintenance status "maintained".
+%
+% The list of all files belonging to the LaTeX base distribution is
+% given in the file `manifest.txt'. See also `legal.txt' for additional
+% information.
+%
+% The list of derived (unpacked) files belonging to the distribution
+% and covered by LPPL is defined by the unpacking scripts (with
+% extension .ins) which are part of the distribution.
+%
+% \fi
+%
+% \iffalse
+%%% From File: lttagging.dtx
+%
+%<*driver>
+% \fi
+\ProvidesFile{lttagging.dtx}
+             [2023/12/19 v1.0a LaTeX Kernel (tagging support)]
+% \iffalse
+\documentclass{l3doc}
+\GetFileInfo{lttagging.dtx}
+\title{\filename}
+\date{\filedate}
+\author{\LaTeX{} project}
+
+\begin{document}
+% \MaintainedByLaTeXTeam{latex}     % should be added again the moment
+                                    % it is supported by l3doc
+ \maketitle
+ \DocInput{\filename}
+\end{document}
+%</driver>
+% \fi
+%
+% \providecommand\env[1]{\texttt{#1}}
+%
+% \providecommand\hook[1]{\texttt{#1\DescribeHook[noprint]{#1}}}
+% \providecommand\socket[1]{\texttt{#1\DescribeSocket[noprint]{#1}}}
+% \providecommand\plug[1]{\texttt{#1\DescribePlug[noprint]{#1}}}
+%
+% \let\ProvideDocElement\NewDocElement
+%
+% \ProvideDocElement[printtype=\textit{socket},idxtype=socket,idxgroup=Sockets]{Socket}{socketdecl}
+% \ProvideDocElement[printtype=\textit{hook},idxtype=hook,idxgroup=Hooks]{Hook}{hookdecl}
+% \ProvideDocElement[printtype=\textit{plug},idxtype=plug,idxgroup=Plugs]{Plug}{plugdecl}
+%
+%
+% \section{}
+%
+%
+%
+% \MaybeStop{}
+%
+%    \begin{macrocode}
+%<*2ekernel|latexrelease>
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\ExplSyntaxOn
+%    \end{macrocode}
+%
+%
+% \section{General support for tagged output}
+%
+%  \DescribeMacro\SuspendTagging
+%  \DescribeMacro\ResumeTagging
+%  
+%  The are places in code where it is import top stop any tagging
+%  activities, e.g., when we are doing trial typesetting that it is
+%  done several times. In such a case one must tag only the final
+%  version that is actually used, otherwise tagging structures are
+%  allowed which then do not end up in the PDF and confuse the
+%  mechanism. For this we have two commands that can be used in
+%  packages: \cs{SuspendTagging} and \cs{ResumeTagging}. They are
+%  available as part of the \LaTeX{} kernel, so that they can be
+%  safely used in packages whether or not tagging is requested .They
+%  both take string argument that is used for debugging to easily
+%  identify why tagging was suspended or restarted, for example, in
+%  \pkg{tabularx} you find \verb=\SuspendTagging{tabularx}=. By default
+%  they two commands do nothing.
+%
+%  TODO: the corresponding L3 layer commands should also have a dummy
+%  definition in the kernel!
+%
+% \DescribeMacro\UseTaggingSocket
+% \DescribeMacro\tag_socket_use:n
+% \DescribeMacro\tag_socket_use:nn
+%  To support tagging in packages we use sockets with names starting
+%  with \texttt{tagsupport/}. Usually, these sockets have exactly two
+%  plugs defined:
+%  \plug{noop} (when no tagging is requested or tagging is not wanted
+%  for some reason) and a second plug that enables the tagging. There
+%  may be more, e.g., tagging with special debugging, etc., but right
+%  now it is usually just on or off.
+%
+%  Given that we sometimes have to suspend tagging, it would be fairly
+%  inefficient to put different plugs into these sockets whenever that
+%  happens. We therefore offer \cs{UseTaggingSocket} which is like
+%  \cs{UseSocket} except that the socket name is specified without
+%  \texttt{tagsupport/}, i.e.,
+% \begin{quote}
+%   \verb=\UseTaggingSocket{foo}=      $\to$
+%   \verb=\UseSocket{tagsupport/foo}=
+% \end{quote}
+%  Beside being slightly shorter, the big advantage is that this way
+%  we can change \cs{UseTaggingSocket} to do nothing when tagging is
+%  suspended with \cs{SuspendTagging} instead of changing the plugs of
+%  the tagging support sockets back and forth.
+%
+%  It is possible to use the tagging support sockets with
+%  \cs{UseSocket} directly, but in this case the socket remains active
+%  if \cs{SuspendTagging} is in force. There my be reasons for doing
+%  that but in general we expect to always use \cs{UseTaggingSocket}.
+%
+%  The L3 programming layer versions \cs{tag_socket_use:n} and
+%  \cs{tag_socket_use:nn} are slightly more efficient than
+%  \cs{UseTaggingSocket} because they do not have to determine how
+%  many arguments the socket takes when disabling it, so in code that
+%  is using the L3 programming layer we recommend to use them instead
+%  of the CamelCase command.
+%                
+%
+%
+%  \begin{macro}{\SuspendTagging,\ResumeTagging}
+%    
+%    In the kernel, these two commands get dummy definitions so that
+%    they can be used without harm in packages. The real definition is
+%    used when tagging gets enabled.
+%    \begin{macrocode}
+\cs_new_eq:NN \SuspendTagging \use_none:n  
+\cs_new_eq:NN \ResumeTagging  \use_none:n
+%    \end{macrocode}
+%
+%    A simplified version of this defnition should move to
+%    \pkg{tagpdf} and dropped here, eventually.
+%    \begin{macrocode}
+\AddToHook{begindocument/before}{
+  \cs_if_exist:NT \tag_stop:n
+  { 
+    \cs_set:Npn \SuspendTagging #1 {
+%    \end{macrocode}%
+%    This stops tagging and also disables all tagging sockets so we are done.
+%    \begin{macrocode}
+      \tag_stop:n {#1} 
+    }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+    \cs_set:Npn \ResumeTagging #1 { \tag_start:n {#1} }
+  }
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%  \begin{macro}{\tag_socket_use:n,
+%                \tag_socket_use:nn,
+%                \UseTaggingSocket,
+%               }
+%    Again this is not the final definition for the kernel; it is just
+%    a version to get going while some parts of the kernel support are
+%    still missing.
+%    \begin{macrocode}
+\AddToHook{begindocument}[kernel]{
+  \cs_if_exist:NF \tag_if_active:T
+     {
+       \prg_new_conditional:Npnn \tag_if_active: { p , T , TF, F }
+           { \prg_return_false: }
+     }
+}
+%    \end{macrocode}
+%
+%    Dummy definitions in the kernel.
+%    These definitions will get updated in \pkg{tagpdf}.
+%    \begin{macrocode}
+\cs_new_protected:Npn \tag_socket_use:n #1 { }
+\cs_new_protected:Npn \tag_socket_use:nn #1#2 { }
+%    \end{macrocode}
+%    The default in the kernel is just to get rid of the argument:
+%    \begin{macrocode}
+\cs_new_protected:Npn \UseTaggingSocket #1 {
+  \int_case:nnF
+      { \int_use:c { c__socket_tagsupport/#1_args_int } }
+         {
+           0 \prg_do_nothing:
+           1 \use_none:n
+           2 \use_none:nn
+%    \end{macrocode}
+%    We do not expect tagging sockets with more than one or two
+%    arguments, so for now we only provide those.
+%    \begin{macrocode}
+         }
+         \ERRORusetaggingsocket  % that should get a proper error message
+}
+\ExplSyntaxOff
+%    \end{macrocode}
+%
+%  \end{macro}
+%
+%
+%
+%
+%
+%
+% \subsection{Tagging support for table/tabular packages}
+%
+% The code uses a number of sockets to inject the tagging
+% commands. These can be easily set to a noop-plug in case the
+% automated tagging is not wanted. 
+%
+% \begin{socketdecl}{tagsupport/tbl/cell/begin,
+%                    tagsupport/tbl/cell/end,
+%                    tagsupport/tbl/pcell/end,
+%                    tagsupport/tbl/pcell/end,
+%                    tagsupport/tbl/row/begin,
+%                    tagsupport/tbl/row/end,
+%                   }
+%     At first sockets for the begin and end of cells and table rows:
+%    \begin{macrocode}
+\NewSocket{tagsupport/tbl/cell/begin}{0}
+\NewSocket{tagsupport/tbl/cell/end}{0}
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\NewSocket{tagsupport/tbl/row/begin}{0}
+\NewSocket{tagsupport/tbl/row/end}{0}
+%    \end{macrocode}
+%    Multi-line cells have their own sockets (as they start out in
+%    vertical mode and need different treatment).
+%    \begin{macrocode}
+\NewSocket{tagsupport/tbl/pcell/begin}{0}
+\NewSocket{tagsupport/tbl/pcell/end}{0}
+%    \end{macrocode}
+% \end{socketdecl}
+%
+% \begin{socketdecl}{tagsupport/tbl/init}
+%    This socket should be at the begin of the table, inside a group.
+%    It is used for settings such as disabling para-tagging inside the
+%    table.  This socket
+%    can perhaps be merged later into the begin-sockets.
+%    \begin{macrocode}
+\NewSocket{tagsupport/tbl/init}{0}
+%    \end{macrocode}
+% \end{socketdecl}
+%
+%
+% \begin{socketdecl}{tagsupport/tbl/finalize}
+%    To fine tune the structure (change cells to header cells, remove
+%    unwanted structures, move a foot to the end, etc.). We also need a
+%    socket that is executed at the end of the table but \emph{before}
+%    all the variables are restored to the outer or default values.
+%    The code in the socket can make assignments, but probably
+%    shouldn't do typesetting and not write whatsits.
+%    \begin{macrocode}
+\NewSocket{tagsupport/tbl/finalize}{0}
+%    \end{macrocode}
+% \end{socketdecl}
+%
+
+
+% \begin{socketdecl}{tagsupport/tbl/colspan}
+%    This socket is used to manage spanning cells, e.g., a
+%    \cs{multicolumn}. It expects one argument (the number of cells
+%    spanned) and if tagging is enabled set appropriate tag attributes
+%    in the background. We probably need a similar socket for row
+%    spans eventually.
+%    \begin{macrocode}
+\NewSocket{tagsupport/tbl/colspan}{1}
+%    \end{macrocode}
+% \end{socketdecl}
+%
+
+
+% \begin{socketdecl}{tagsupport/tbl/hmode/begin,
+%                    tagsupport/tbl/hmode/end,
+%                    tagsupport/tbl/vmode/begin,
+%                    tagsupport/tbl/vmode/end
+%                   }
+%
+%    These sockets are used in the begin and end code of environments,
+%    to allow a fast enabling and disabling of the tagging. We
+%    distinguish between tables that can be used inside paragraphs and
+%    standalone tables such as \env{longtable} that are always in
+%    vertical mode.
+%    \begin{macrocode}
+\NewSocket{tagsupport/tbl/hmode/begin}{0}
+\NewSocket{tagsupport/tbl/hmode/end}{0}
+\NewSocket{tagsupport/tbl/vmode/begin}{0}
+\NewSocket{tagsupport/tbl/vmode/end}{0}
+%    \end{macrocode}
+% \end{socketdecl}
+%
+%
+%
+% \begin{socketdecl}{tagsupport/tbl/longtable/init,
+%                    tagsupport/tbl/longtable/finalize}
+%    \env{longtable} needs its own sockets to fine tune the structure.
+%    Simply switching the plug in the previous socket interferes with
+%    enabling/disabling the tagging.
+%    \begin{macrocode}
+\NewSocket{tagsupport/tbl/longtable/init}{0}
+\NewSocket{tagsupport/tbl/longtable/finalize}{0}
+%    \end{macrocode}
+% \end{socketdecl}
+%
+% \begin{socketdecl}{tagsupport/tbl/longtable/head,
+%                    tagsupport/tbl/longtable/foot}
+%    Header and footer boxes need special handling because they are repeatedly
+%    used.
+%    \begin{macrocode}
+\NewSocket{tagsupport/tbl/longtable/head}{0}
+\NewSocket{tagsupport/tbl/longtable/foot}{0}
+%    \end{macrocode}
+% \end{socketdecl}
+%
+%
+%
+%
+%
+% \section{For lttab.dtx parked here for now}
+%
+%    
+%    \begin{macrocode}
+%<@@=tbl>
+\ExplSyntaxOn
+%    \end{macrocode}
+%
+%
+% \subsection{Variables for row, column and span counting}
+%
+%  This part needs a decision on names for various integer registers
+%  as well as a decision if those should be also made available for
+%  \LaTeXe{}-style packages in form of 2e names and or as
+%  non-internals for the L3 programming layer.
+%
+%  At the moment they are all internal but this probably has to change.
+%
+%  \begin{macro}{
+%     \g_@@_col_int,
+%     \g_@@_row_int,
+%     \g_@@_span_tl,
+%     \g_@@_table_cols_tl}
+%    
+%    \cs{g_@@_row_int} holds the current row number in the table. The
+%    value \texttt{0} means we haven't yet processed the table
+%    preamble (or in case of longtable are just in front of the next
+%    chunk to be processed). It is incremented by every \cs{cr}
+%    including the one ending the table preamble.
+%
+%    TODO: due to the gymnastics needed inside the longtable code the
+%    row counter is directly exposed there rather than hidden by
+%    interfaces. This needs changing when it is decided how to manage
+%    these counters.
+%
+%    \cs{g_@@_col_int} holds the current column number. The value
+%    \texttt{0} means we have not yet started the table or just finished a table row
+%    (with \verb=\\= typically); any other positive value means we
+%    are currently typesetting a cell in that column in some row
+%    (denoted by the \cs{g_@@_row_int}).
+%
+%    In a \cs{multicolumn} it holds the column number of the first
+%    spanned column and \cs{g_@@_span_tl} the info how many cells are
+%    spanned.
+%
+%    \cs{g_@@_span_tl} is normally \texttt{1} except in a
+%    \cs{multicolumn} cell.
+%    \begin{macrocode}
+\int_new:N \g_@@_col_int
+\int_new:N \g_@@_row_int
+\tl_new:N  \g_@@_span_tl
+\tl_new:N  \g_@@_table_cols_tl
+
+\tl_gset:Nn \g_@@_span_tl {1}
+\tl_gset:Nn \g_@@_table_cols_tl {0}  % indicates outer level
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\l_@@_saved_col_tl,\l_@@_saved_row_tl,
+%                \l_@@_saved_span_tl,\l_@@_saved_table_cols_tl}
+%
+%    Saving the outer values if we are nesting tables is necessary (as
+%    the above variables are globally altered). For this we always use
+%    token lists because they don't change and we do not need to blow
+%    additional integer registers.
+%    \begin{macrocode}
+\tl_new:N \l_@@_saved_col_tl
+\tl_new:N \l_@@_saved_row_tl
+\tl_new:N \l_@@_saved_span_tl
+\tl_new:N \l_@@_saved_table_cols_tl
+
+\tl_set:Nn \l_@@_saved_col_tl{0}
+\tl_set:Nn \l_@@_saved_row_tl{0}
+\tl_set:Nn \l_@@_saved_span_tl{1}
+\tl_set:Nn \l_@@_saved_table_cols_tl{0}  % indicates outer level
+%    \end{macrocode}
+%  \end{macro}
+%
+%  \begin{macro}{\g_@@_missingcells_int}
+% This will contain the number of missing cells in a row:
+%    \begin{macrocode}
+\int_new:N \g_@@_missing_cells_int
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%
+%
+% \subsection{Tracing/debugging}
+%
+%  \begin{macro}{\DebugTablesOn,\DebugTablesOff}
+%    
+%    \begin{macrocode}
+\def\DebugTablesOn{
+  \cs_set_eq:NN \@@_trace:n \typeout
+}  
+\def\DebugTablesOff{
+  \cs_set_eq:NN \@@_trace:n \use_none:n
+}  
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\cs_new_eq:NN \@@_trace:n \use_none:n
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+% \subsection{Interface commands}
+%
+% All interface commands for the cell number determination have to be
+% public on some level because they are needed in other packages as
+%  well, e.g., longtable. We may or may not also want to provide 2e
+%  style names for them.
+%
+%  \begin{macro}{\tbl_update_cell_data:}
+%    Updating cell data in columns after the first means we have to
+%    increment the \cs{g_@@_col_int} by the span count of the previous
+%    cell (in case it was a \cs{multicolumn}) and then reset the
+%    \cs{g_@@_span_tl} to one (as the default).
+%    \begin{macrocode}
+\cs_new_protected:Npn \tbl_update_cell_data: {
+        \int_gadd:Nn \g_@@_col_int { \g_@@_span_tl }
+        \tl_gset:Nn  \g_@@_span_tl {1}
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%  \begin{macro}{\tbl_count_table_cols:}
+%    Current implementation of \cs{@mkpream} uses the scratch counter
+%    \cs{count@} to keep track of the number of toks registers it needs
+%    (2 per column), but this can't be used as it counts also
+%    insertions made with \verb+!{}+ and \verb+@{}+.
+%    So similar as does longtable for \cs{LT@cols} we count the
+%    numbers of ampersands instead.
+%    \begin{macrocode}
+\cs_new:Npn \tbl_count_table_cols:  {
+  \seq_set_split:NnV\l_@@_tmpa_seq {&}\@preamble
+  \tl_gset:Ne \g_@@_table_cols_tl { \seq_count:N \l_@@_tmpa_seq }
+  \@@_trace:n { ==>~ Table~ has~ \g_@@_table_cols_tl \space columns }
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\l_@@_tmpa_seq}
+%    
+%    \begin{macrocode}
+\seq_new:N \l_@@_tmpa_seq
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%  \begin{macro}{\tbl_count_missing_cells:n}
+%    
+%    We might have the situation that some table package has not
+%    implemented the \cs{tbl_count_table_cols:} in which case
+%    \cs{g_@@_table_cols_tl} would always be zero and we would get an
+%    error below when we try to determine the missing cells, so bypass
+%    that calculation if we aren't doing tagging (there the packages
+%    should have the proper code added). Recall that this is code,
+%    that is called by \verb=\\= and an old table packagee might rely
+%    on whatever the \LaTeX{} kernel offers here.
+%    \begin{macrocode}
+\cs_new:Npn \tbl_count_missing_cells:n #1 {
+  \tag_if_active:T {
+    \int_compare:nNnT \g_@@_col_int > 0
+      {
+        \int_gset:Nn \g_@@_missing_cells_int
+            {
+              \g_@@_table_cols_tl
+            - \g_@@_col_int
+            - \g_@@_span_tl
+            + 1
+            }
+        \int_compare:nNnT \g_@@_missing_cells_int < 0 \ERRORmissingcells % should not happen
+        \@@_trace:n{==>~
+          (#1)~
+          This~ row~ needs~
+          \int_use:N \g_@@_missing_cells_int \space
+          additional~ cell(s)
+        }
+      }
+  }
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\tbl_save_outer_table_cols:}
+%    
+%    \begin{macrocode}
+\cs_new_protected:Npn \tbl_save_outer_table_cols: {
+  \tl_set_eq:NN \l_@@_saved_table_cols_tl  \g_@@_table_cols_tl
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\tbl_init_cell_data_for_table:}
+%    
+%    \begin{macrocode}
+\cs_new_protected:Npn \tbl_init_cell_data_for_table: {
+  \tl_set:No \l_@@_saved_col_tl {\int_use:N \g_@@_col_int }
+  \tl_set:No \l_@@_saved_row_tl {\int_use:N \g_@@_row_int }
+  \tl_set_eq:NN \l_@@_saved_span_tl  \g_@@_span_tl
+%
+  \@@_trace:n { ==>~ saved~cell~data:~
+                \l_@@_saved_row_tl,
+                \l_@@_saved_col_tl,
+                \l_@@_saved_span_tl \space
+                (
+                \int_compare:nNnTF \l_@@_saved_table_cols_tl = 0
+                    { outer~ level }
+                    { max:~ \l_@@_saved_table_cols_tl }
+                )
+          }
+%    \end{macrocode}
+%    These are the initial values when starting a table:
+%    \begin{macrocode}
+  \int_gzero:N \g_@@_row_int
+  \int_gzero:N \g_@@_col_int
+  \tl_gset:Nn  \g_@@_span_tl {1}
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%
+%  \begin{macro}{\tbl_update_cell_data_for_next_row:}
+%    \begin{macrocode}
+\cs_new_protected:Npn \tbl_update_cell_data_for_next_row: {
+      \int_gincr:N \g_@@_row_int          % this row about to start
+      \int_gzero:N \g_@@_col_int          % we are before first col
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\tbl_init_cell_data_for_row:}
+%    If we start processing a cell in the first column  we set
+%    \cs{g_@@_col_int} to \texttt{1} as we are no longer "at" but "in"
+%    the first column. We also set \cs{g_@@_span_tl} to its default
+%    value (not spanning cells).
+%    \begin{macrocode}
+\cs_new_protected:Npn \tbl_init_cell_data_for_row: {
+        \int_gset:Nn \g_@@_col_int {1}
+        \tl_gset:Nn  \g_@@_span_tl {1}
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\tbl_if_row_was_started:T,
+%                \tbl_if_row_was_started:TF}
+%    We use \cs{g_@@_col_int} equal zero to indicate that we are just
+%    after a TR (i.e.n between rows or at the very beginning of the
+%    table). Using the row
+%    count is not so good as longtable may split the table in chunks.
+%
+%    These conditionals have to be expandable (i.e., unprotected) as
+%    they are sometimes executed when \TeX{} is scanning inside a table.
+%    \begin{macrocode}
+\cs_new:Npn \tbl_if_row_was_started:T {
+      \int_compare:nNnT \g_@@_col_int > 0
+}
+\cs_new:Npn \tbl_if_row_was_started:TF {
+      \int_compare:nNnTF \g_@@_col_int > 0
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%  \begin{macro}{\tbl_gzero_row_count:,\tbl_gincr_row_count:,\tbl_gdecr_row_count:}
+%    This here is basically a temporary interface. What it will be in
+%    the end depends on what we decide concerning exposing row and
+%    column counters, if they stay internal we need something like
+%    this here (perhaps using \texttt{gincr} etc, or perhaps some
+%    other names in the first place).
+%    \begin{macrocode}
+\cs_new_protected:Npn \tbl_gzero_row_count: {
+  \int_gzero:N \g_@@_row_int
+}
+\cs_new_protected:Npn \tbl_gincr_row_count: {
+  \int_gincr:N \g_@@_row_int
+}
+\cs_new_protected:Npn \tbl_gdecr_row_count: {
+  \int_gdecr:N \g_@@_row_int
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%  \begin{macro}{\tbl_inbetween_rows:}
+%    Again name is not really brilliant so far.
+%    \begin{macrocode}
+\cs_new_protected:Npn \tbl_inbetween_rows: {
+       \int_gzero:N  \g_@@_col_int
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%
+%
+%
+%  \begin{macro}{\tbl_restore_outer_cell_data:}
+%    
+%    \begin{macrocode}
+\cs_new_protected:Npn \tbl_restore_outer_cell_data: {
+  \int_gset:Nn \g_@@_col_int { \l_@@_saved_col_tl }
+  \int_gset:Nn \g_@@_row_int { \l_@@_saved_row_tl }
+  \tl_gset_eq:NN \g_@@_span_tl \l_@@_saved_span_tl
+  \tl_gset_eq:NN \g_@@_table_cols_tl   \l_@@_saved_table_cols_tl
+  \@@_trace:n { ==>~ restored~cell~data:~
+                \int_use:N \g_@@_row_int,
+                \int_use:N \g_@@_col_int,
+                \l_@@_saved_span_tl \space
+                (
+                \int_compare:nNnTF \g_@@_table_cols_tl = 0
+                    { outer~ level }
+                    { max:~ \g_@@_table_cols_tl }
+                )
+              }
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%  \begin{macro}{\tbl_update_multicolumn_cell_data:n}
+%    This macro updates \cs{g_@@_col_int} and \cs{g_@@_span_tl} inside
+%    a \cs{multicolumn} and possibly calls the tagging socket
+%    \texttt{tbl/row/begin}.
+%    \begin{macrocode}
+\cs_new_protected:Npn \tbl_update_multicolumn_cell_data:n #1 {
+%    \end{macrocode}
+%    We execute socket for tagging only if this \cs{multicolumn}
+%    replaces the preamble of the first column. In that case we also have
+%    to set \cs{g_@@_col_int} to 1 because this is no longer done in the
+%    preamble for the cell either.
+%    \begin{macrocode}
+   \int_compare:nNnTF \g_@@_col_int = 0
+       {
+         \UseTaggingSocket{tbl/row/begin}
+         \int_gset:Nn \g_@@_col_int {1}
+       }
+%    \end{macrocode}
+%    If we are in a later column we use \cs{g_@@_span_tl} from the
+%    previous column to update.
+%    \begin{macrocode}
+       {
+         \int_gadd:Nn \g_@@_col_int { \g_@@_span_tl }
+       }
+%    \end{macrocode}
+%    Then we set the span value so that it can be use in the next column.
+%    \begin{macrocode}
+   \tl_gset:Nn \g_@@_span_tl {#1}
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%  \begin{macro}{\tbl_crcr:n}
+%    This macro is used instead of the usual \cs{crcr} at the end of a
+%    table. It is deliberately defined without protection because it
+%    may get expanded by the scanning mechanism of low-level \TeX{}
+%    after a final \cs{cr} (aka \verb=\\=) in the table. In that case
+%    it shouldn't stop the expansion and the conditional inside will
+%    be false, thus it just vanishes without doing anything. If there
+%    are missing cells (in which case we also haven't see \cs{cr} yet)
+%    the macro \cs{tbl_count_missing_cells:n} is executed and
+%    then the row is finished with a final \cs{cr}.
+%    \begin{macrocode}
+\cs_new:Npn \tbl_crcr:n #1 {  
+    \int_compare:nNnT \g_@@_col_int > 0
+        {
+          \tbl_count_missing_cells:n {#1}
+          \cr
+        }
+}
+%    \end{macrocode}
+%  \end{macro}
+%
+%
+%
+%    \begin{macrocode}
+\ExplSyntaxOff
+%<@@=>
+%    \end{macrocode}
+%
+%    This is needed for \pkg{longtable} because \cs{refstepcounter} is
+%    setting up a target when \pkg{hyperref} is loaded and we don't
+%    want that in \pkg{longtable}.
+%
+%    TODO: move to right .dtx file
+%    \begin{macrocode}
+\let\@kernel@refstepcounter\refstepcounter
+%    \end{macrocode}
+%    Prevent longtable patching by hyperref until hyperref does so automatically:
+%    \begin{macrocode}
+\def\hyper@nopatch@longtable{}
+%    \end{macrocode}
+%
+%
+% Should there be a module?
+%
+%    \begin{macrocode}
+%<latexrelease>\NewModuleRelease{2024/06/01}{lttagging}
+%<latexrelease>                 {Tagging support}
+%    \end{macrocode}
+%
+%
+%
+%
+%    \begin{macrocode}
+%<latexrelease>\IncludeInRelease{0000/00/00}{lttagging}%
+%<latexrelease>                 {Undo tagging support}
+%<latexrelease>
+%<latexrelease>
+%<latexrelease>
+%<latexrelease>\EndModuleRelease
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+%</2ekernel|latexrelease>
+%    \end{macrocode}
+%
+% \Finale
+%