CTAN sync 202106210301

4 files changed, 666 insertions, 707 deletions

diff --git a/macros/latex/contrib/nicematrix/nicematrix-french.pdf b/macros/latex/contrib/nicematrix/nicematrix-french.pdf
index 646ec7e301..55b39da0c4 100644
--- a/macros/latex/contrib/nicematrix/nicematrix-french.pdf
+++ b/macros/latex/contrib/nicematrix/nicematrix-french.pdf
diff --git a/macros/latex/contrib/nicematrix/nicematrix-french.tex b/macros/latex/contrib/nicematrix/nicematrix-french.tex
index c80c13f352..5339ea7ac8 100644
--- a/macros/latex/contrib/nicematrix/nicematrix-french.tex
+++ b/macros/latex/contrib/nicematrix/nicematrix-french.tex
@@ -531,11 +531,10 @@ cette clé (la valeur par défaut est 4~pt\footnote{Cette valeur par défaut est
 \item la clé |borders| permet de ne tracer que certaines des bordures du bloc :
 cette clé prend comme valeur une liste d'éléments parmi les suivants : |left|,
 |right|, |top| et |bottom| ;
+\item les clés |t| et |b| réglent la ligne de base qui sera donnée au bloc quand
+celui-ci est constitué de plusieurs lignes (séparées par la commande |\\|) ;
 \item \colorbox{yellow!50}{\bfseries Nouveau 5.15}\enskip la clé |hvlines| trace
-tous les filets horizontaux et verticaux dans le bloc ;
-\item \colorbox{yellow!50}{\bfseries Nouveau 5.14}\enskip les clés |t| et |b|
-réglent la ligne de base qui sera donnée au bloc quand celui-ci est constitué de
-plusieurs lignes (séparées par la commande |\\|).
+tous les filets horizontaux et verticaux dans le bloc.
 \end{itemize}
 
 
@@ -1050,12 +1049,11 @@ A & A & A & A & A & A \\
 
 
 \bigskip
-\colorbox{yellow!50}{\textbf{Nouveau 5.14}}\enskip Quand la clé |corners| est
-utilisée, \pkg{nicematrix} calcule les coins vides et ces coins sont alors pris
-en compte par les outils de tracés de filets (les filets ne seront pas tracés
-dans ces coins vides). \emph{Remarque} : Dans les versions précédentes de
-\pkg{nicematrix}, il n'y avait qu'une clé |hvlines-except-corners| (maintenant
-considérée comme obsolète).
+Quand la clé |corners| est utilisée, \pkg{nicematrix} calcule les coins vides et
+ces coins sont alors pris en compte par les outils de tracés de filets (les
+filets ne seront pas tracés dans ces coins vides). \emph{Remarque} : Dans les
+versions précédentes de \pkg{nicematrix}, il n'y avait qu'une clé
+|hvlines-except-corners| (maintenant considérée comme obsolète).
 
 \bigskip
 \begin{BVerbatim}[boxwidth=11cm,baseline=c]
@@ -3538,28 +3536,23 @@ Dans l'exemple suivant, nous avons surligné tous les nœuds de la matrice (on
 explique plus loin la technique utilisée : cf. p. \pageref{highlight}).
 
 \[\begin{pNiceMatrix}
+\CodeBefore [create-cell-nodes]
+   \begin{tikzpicture}%
+     [every node/.style = { inner sep = 0 pt , fill = red!15 }]
+   \node [fit = (1-1)] {} ;
+   \node [fit = (1-3)] {} ;
+   \node [fit = (2-2)] {} ;
+   \node [fit = (3-1)] {} ;
+   \node [fit = (3-3)] {} ;
+   \node [fit = (1-2)] {} ;
+   \node [fit = (2-1)] {} ;
+   \node [fit = (2-3)] {} ;
+   \node [fit = (3-2)] {} ;
+   \end{tikzpicture}
+\Body
 a & a + b & a + b + c \\
 a & a     & a + b  \\
 a & a     & a 
-\CodeAfter
-\begin{tikzpicture}[ 
-                     every node/.style = 
-                       { 
-                         blend mode = multiply,
-                         inner sep = 0 pt ,
-                         fill = red!15
-                       }
-                   ]
-\node [fit = (1-1)] {} ;
-\node [fit = (1-3)] {} ;
-\node [fit = (2-2)] {} ;
-\node [fit = (3-1)] {} ;
-\node [fit = (3-3)] {} ;
-\node [fit = (1-2)] {} ;
-\node [fit = (2-1)] {} ;
-\node [fit = (2-3)] {} ;
-\node [fit = (3-2)] {} ;
-\end{tikzpicture}
 \end{pNiceMatrix}\]
 
 
@@ -3583,25 +3576,24 @@ nom des nœuds normaux. Dans l'exemple suivant, on a surligné tous les «nœuds
 moyens». Nous considérons que cet exemple se suffit à lui-même comme définition
 de ces nœuds.
 \[\begin{pNiceMatrix}[create-medium-nodes]
+\CodeBefore [create-cell-nodes]
+   \begin{tikzpicture} 
+      [every node/.style = {fill = red!15, inner sep = 0 pt},
+       name suffix = -medium]
+   \node [fit = (1-1)] {} ;
+   \node [fit = (1-2)] {} ;
+   \node [fit = (1-3)] {} ;
+   \node [fit = (2-1)] {} ;
+   \node [fit = (2-2)] {} ;
+   \node [fit = (2-3)] {} ;
+   \node [fit = (3-1)] {} ;
+   \node [fit = (3-2)] {} ;
+   \node [fit = (3-3)] {} ;
+\end{tikzpicture}
+\Body
 a & a + b & a + b + c \\
 a & a     & a + b  \\
 a & a     & a 
-\CodeAfter
-\begin{tikzpicture}
-   [every node/.style = {fill = red!15,
-                         blend mode = multiply,
-                         inner sep = 0 pt},
-    name suffix = -medium]
-\node [fit = (1-1)] {} ;
-\node [fit = (1-2)] {} ;
-\node [fit = (1-3)] {} ;
-\node [fit = (2-1)] {} ;
-\node [fit = (2-2)] {} ;
-\node [fit = (2-3)] {} ;
-\node [fit = (3-1)] {} ;
-\node [fit = (3-2)] {} ;
-\node [fit = (3-3)] {} ;
-\end{tikzpicture}
 \end{pNiceMatrix}\]
 
 
@@ -3614,24 +3606,24 @@ de ces nÅ“uds.\footnote{Il n'y a pas de «nÅ“uds larges» créés dans les rangÃ
   p.~\pageref{exterior}).}
 
 \[\begin{pNiceMatrix}[create-large-nodes]
+\CodeBefore [create-cell-nodes]
+   \begin{tikzpicture}
+      [every node/.style = { inner sep = 0 pt} ,
+       name suffix = -large]
+   \node [fit = (1-1),fill = red!15] {} ;
+   \node [fit = (1-3),fill = red!15] {} ;
+   \node [fit = (2-2),fill = red!15] {} ;
+   \node [fit = (3-1),fill = red!15] {} ;
+   \node [fit = (3-3),fill = red!15] {} ;
+   \node [fit = (1-2),fill = blue!15] {} ;
+   \node [fit = (2-1),fill = blue!15] {} ;
+   \node [fit = (2-3),fill = blue!15] {} ;
+   \node [fit = (3-2),fill = blue!15] {} ;
+   \end{tikzpicture}
+\Body
 a & a + b & a + b + c \\
 a & a     & a + b  \\
 a & a     & a 
-\CodeAfter
-\begin{tikzpicture}
-   [every node/.style = {blend mode = multiply,
-                         inner sep = 0 pt},
-    name suffix = -large]
-\node [fit = (1-1),fill = red!15] {} ;
-\node [fit = (1-3),fill = red!15] {} ;
-\node [fit = (2-2),fill = red!15] {} ;
-\node [fit = (3-1),fill = red!15] {} ;
-\node [fit = (3-3),fill = red!15] {} ;
-\node [fit = (1-2),fill = blue!15] {} ;
-\node [fit = (2-1),fill = blue!15] {} ;
-\node [fit = (2-3),fill = blue!15] {} ;
-\node [fit = (3-2),fill = blue!15] {} ;
-\end{tikzpicture}
 \end{pNiceMatrix}\]
 
 
@@ -3647,24 +3639,24 @@ utilisé les options |left-margin| et |right-margin|.\footnote{Les options
   elle est égale à |\arraycolsep| (valeur initiale : 5~pt). Il existe aussi une
   option |margin| pour fixer à la fois |left-margin| et |right-margin|.}
 \[\begin{pNiceMatrix}[create-large-nodes,left-margin,right-margin]
+\CodeBefore [create-cell-nodes]
+    \begin{tikzpicture}
+       [every node/.style = {inner sep = 0 pt},
+        name suffix = -large]
+    \node [fit = (1-1),fill = red!15] {} ;
+    \node [fit = (1-3),fill = red!15] {} ;
+    \node [fit = (2-2),fill = red!15] {} ;
+    \node [fit = (3-1),fill = red!15] {} ;
+    \node [fit = (3-3),fill = red!15] {} ;
+    \node [fit = (1-2),fill = blue!15] {} ;
+    \node [fit = (2-1),fill = blue!15] {} ;
+    \node [fit = (2-3),fill = blue!15] {} ;
+    \node [fit = (3-2),fill = blue!15] {} ;
+    \end{tikzpicture}
+\Body
 a & a + b & a + b + c \\
 a & a     & a + b  \\
 a & a     & a 
-\CodeAfter
-\begin{tikzpicture}
-   [every node/.style = {blend mode = multiply,
-                         inner sep = 0 pt},
-    name suffix = -large]
-\node [fit = (1-1),fill = red!15] {} ;
-\node [fit = (1-3),fill = red!15] {} ;
-\node [fit = (2-2),fill = red!15] {} ;
-\node [fit = (3-1),fill = red!15] {} ;
-\node [fit = (3-3),fill = red!15] {} ;
-\node [fit = (1-2),fill = blue!15] {} ;
-\node [fit = (2-1),fill = blue!15] {} ;
-\node [fit = (2-3),fill = blue!15] {} ;
-\node [fit = (3-2),fill = blue!15] {} ;
-\end{tikzpicture}
 \end{pNiceMatrix}\]
 
 \medskip
@@ -3674,24 +3666,24 @@ incorporées dans les «nœuds larges». Dans l'exemple suivant, nous avons util
 |extra-left-margin| et |extra-right-margin| avec la valeur $3$~pt.
 \[\begin{pNiceMatrix}%
    [create-large-nodes,left-margin,right-margin,extra-right-margin=3pt,extra-left-margin=3pt]
+\CodeBefore [create-cell-nodes]
+    \begin{tikzpicture}
+       [every node/.style = {inner sep = 0 pt},
+        name suffix = -large]
+    \node [fit = (1-1),fill = red!15] {} ;
+    \node [fit = (1-3),fill = red!15] {} ;
+    \node [fit = (2-2),fill = red!15] {} ;
+    \node [fit = (3-1),fill = red!15] {} ;
+    \node [fit = (3-3),fill = red!15] {} ;
+    \node [fit = (1-2),fill = blue!15] {} ;
+    \node [fit = (2-1),fill = blue!15] {} ;
+    \node [fit = (2-3),fill = blue!15] {} ;
+    \node [fit = (3-2),fill = blue!15] {} ;
+\end{tikzpicture}
+\Body
 a & a + b & a + b + c \\
 a & a     & a + b  \\
 a & a     & a 
-\CodeAfter
-\begin{tikzpicture}
-   [every node/.style = {blend mode = multiply,
-                         inner sep = 0 pt},
-    name suffix = -large]
-\node [fit = (1-1),fill = red!15] {} ;
-\node [fit = (1-3),fill = red!15] {} ;
-\node [fit = (2-2),fill = red!15] {} ;
-\node [fit = (3-1),fill = red!15] {} ;
-\node [fit = (3-3),fill = red!15] {} ;
-\node [fit = (1-2),fill = blue!15] {} ;
-\node [fit = (2-1),fill = blue!15] {} ;
-\node [fit = (2-3),fill = blue!15] {} ;
-\node [fit = (3-2),fill = blue!15] {} ;
-\end{tikzpicture}
 \end{pNiceMatrix}\]
 
 
@@ -3748,28 +3740,38 @@ Voici maintenant tous les «nœuds larges» de ce tableau (sans utilisation de
 \begin{scope}
 \large
 \begin{NiceTabular}[c]{w{l}{2cm}ll}[hvlines,create-large-nodes]
+\CodeBefore [create-cell-nodes]
+    \begin{tikzpicture}
+       [every node/.style = {inner sep = 0 pt},
+        name suffix = -large]
+    \node [fit = (1-1),fill = red!15] {} ;
+    \node [fit = (1-3),fill = red!15] {} ;
+    \node [fit = (2-2),fill = red!15] {} ;
+    \node [fit = (3-1),fill = red!15] {} ;
+    \node [fit = (3-3),fill = red!15] {} ;
+    \node [fit = (1-2),fill = blue!15] {} ;
+    \node [fit = (2-1),fill = blue!15] {} ;
+    \node [fit = (2-3),fill = blue!15] {} ;
+    \node [fit = (3-2),fill = blue!15] {} ;
+    \end{tikzpicture}
+\Body
 fraise & amande & abricot \\
 prune & pêche & poire  \\[1ex]
 noix & noisette & brugnon
-\CodeAfter
-\begin{tikzpicture}
-   [every node/.style = {blend mode = multiply,
-                         inner sep = 0 pt},
-    name suffix = -large]
-\node [fit = (1-1),fill = red!15] {} ;
-\node [fit = (1-3),fill = red!15] {} ;
-\node [fit = (2-2),fill = red!15] {} ;
-\node [fit = (3-1),fill = red!15] {} ;
-\node [fit = (3-3),fill = red!15] {} ;
-\node [fit = (1-2),fill = blue!15] {} ;
-\node [fit = (2-1),fill = blue!15] {} ;
-\node [fit = (2-3),fill = blue!15] {} ;
-\node [fit = (3-2),fill = blue!15] {} ;
-\end{tikzpicture}
 \end{NiceTabular}
 \end{scope}
 
 
+\vspace{1cm}
+Les nœuds que l'on vient de décrire ne sont pas accessibles par défaut dans le
+|\CodeBefore| (décrit p.~\pageref{code-before}). \par\nobreak
+
+\colorbox{yellow!50}{\textbf{Nouveau 5.16}}\enskip On peut rendre ces nœuds
+accessibles dans le |\CodeBefore| en utilisant la clé |create-cell-nodes| du
+mot-clé |\CodeBefore| (dans ce cas-là, les nœuds sont créés une première fois
+avant la construction du tableau en utilisant des informations écrites dans le
+fichier |aux| puis recréés lors de la composition du tableau proprement dit).
+
 
 \subsection{Les nœuds indiquant la position des filets}
 
@@ -3779,11 +3781,8 @@ L'extension \pkg{nicematrix} crée un nœud PGF-Tikz nommé simplement $i$ (pré
 du préfixe habituel) à l'intersection du filet horizontal de numéro $i$ et du
 filet vertical de numéro~$i$ (ou plutôt la position potentielle de ces filets
 car ils ne sont peut-être pas tracés). Le dernier nœud a aussi un alias nommé
-simplement |last|.
-
-\smallskip
-\colorbox{yellow!50}{\textbf{Nouveau 5.14}}\enskip Il existe aussi un nœud nommé
-$i$|.5| à mi-chemin entre le nœud $i$ et le nœud $i+1$.
+simplement |last|. Il existe aussi un nœud nommé $i$|.5| à mi-chemin entre le
+nœud $i$ et le nœud $i+1$.
 
 Ces nœuds sont accessibles dans le
 |\CodeAfter| mais aussi dans le |\CodeBefore|.
@@ -4759,17 +4758,12 @@ suivantes dans le préambule du document :
 
 \medskip
 Nous créons un nœud Tikz rectangulaire qui englobe les nœuds de la deuxième
-rangée en utilisant les outils de la bibliothèque Tikz \pkg{fit}. Ce nœud est
-rempli après la construction de la matrice. Pour que l'on puisse voir le texte
-\emph{sous} le nœud, nous devons utiliser la transparence avec le |blend mode|
-égal à |multiply|. \textbf{Attention} : Certains lecteurs de \textsc{pdf}
-n'affichent pas la transparence.\footnote{Dans Overleaf, the lecteur de
-  \textsc{PDF} «intégré» n'affiche pas la transparence. On peut sélectionner le
-  lecteur «natif» dans ce cas-là.}
+rangée en utilisant les outils de la bibliothèque Tikz \pkg{fit}. Ces nœuds ne
+sont pas créés par défaut dans le |\CodeBefore| (par souci d'efficacité). Il
+faut utiliser la clé |create-cell-nodes| du |\CodeBefore| pour demander leur création.
 
 \tikzset{highlight/.style={rectangle,
                            fill=red!15,
-                           blend mode = multiply, 
                            rounded corners = 0.5 mm, 
                            inner sep=1pt,
                            fit=#1}}
@@ -4778,119 +4772,59 @@ n'affichent pas la transparence.\footnote{Dans Overleaf, the lecteur de
 \begin{Verbatim}
 \tikzset{highlight/.style={rectangle,
                            fill=red!15,
-                           ~emphase#blend mode = multiply@,
                            rounded corners = 0.5 mm, 
                            inner sep=1pt,
                            fit=~#1}}
 
 $\begin{bNiceMatrix}
+~emphase#\CodeBefore [create-cell-nodes] @
+~emphase#  \tikz \node [highlight = (2-1) (2-3)] {} ; @
+~emphase# \Body @
 0 & \Cdots & 0 \\
 1 & \Cdots & 1 \\
 0 & \Cdots & 0 \\
-~emphase#\CodeAfter \tikz \node [highlight = (2-1) (2-3)] {} ;@
 \end{bNiceMatrix}$
 \end{Verbatim}
 
 \[\begin{bNiceMatrix}
+\CodeBefore [create-cell-nodes] 
+  \tikz \node [highlight = (2-1) (2-3)] {} ;
+\Body
 0 & \Cdots & 0 \\
 1 & \Cdots & 1 \\
 0 & \Cdots & 0 \\
-\CodeAfter \tikz \node [highlight = (2-1) (2-3)] {} ; 
 \end{bNiceMatrix}\]
 
 
 
-\vspace{1cm} On rappelle que dans le cas d'un ensemble de cases fusionnées (avec
-la commande |\Block|), un nœud Tikz est créé pour l'ensemble des cases avec pour
-nom $i$|-|$j$|-block| où $i$ et $j$ sont les numéros de ligne et de colonne de
-la case en haut à gauche (où a été utilisée la commande |\Block|). Si on a
-demandé la création des nœuds |medium|, alors un nœud de ce type est aussi créé
-pour ce bloc avec un nom suffixé par |-medium|.
-
-\medskip
-\begin{BVerbatim}[baseline=c,boxwidth=11.6cm]
-$\begin{pNiceMatrix}[margin,create-medium-nodes]
-  \Block{3-3}<\Large>{A} & & & 0 \\
-  & \hspace*{1cm} & & \Vdots \\
-  & & & 0 \\
-  0 & \Cdots& 0 & 0
-\CodeAfter
-  \tikz \node [~emphase#highlight = (1-1-block-medium)@] {} ;
-\end{pNiceMatrix}$
-\end{BVerbatim}
-$\begin{pNiceMatrix}[margin,create-medium-nodes]
-\Block{3-3}<\Large>{A} & & & 0 \\
-& \hspace*{1cm} & & \Vdots \\
-& & & 0 \\
-0 & \Cdots& 0 & 0
-\CodeAfter
-\tikz \node [highlight = (1-1-block-medium)] {} ;
-\end{pNiceMatrix}$
-
-
 
 \vspace{1cm}
-On considère maintenant la matrice suivante que l'on a appelée |exemple|.
+On considère maintenant la matrice suivante. Si on veut surligner chaque rangée
+de la matrice, on peut utiliser la technique précédente trois fois. 
 
-\medskip
 \begin{Verbatim}
-$\begin{pNiceArray}{ccc}[~emphase#name=exemple@,last-col,create-medium-nodes]
-a & a + b & a + b + c & L_1 \\
-a & a     & a + b     & L_2 \\
-a & a     & a         & L_3
-\end{pNiceArray}$
-\end{Verbatim}
-                          
 \[\begin{pNiceArray}{ccc}[last-col]
+\CodeBefore [create-cell-nodes]
+  \begin{tikzpicture}
+~emphase#  \node [highlight = (1-1) (1-3)] {} ;@
+~emphase#  \node [highlight = (2-1) (2-3)] {} ;@
+~emphase#  \node [highlight = (3-1) (3-3)] {} ;@
+  \end{tikzpicture}
+\Body
 a & a + b & a + b + c & L_1 \\
 a & a     & a + b     & L_2 \\
 a & a     & a         & L_3
 \end{pNiceArray}\]
-
-\bigskip
-Si on veut surligner chaque rangée de la matrice, on peut utiliser la technique précédente trois fois.
-
-\begin{Verbatim}
-\tikzset{mes-options/.style={remember picture, 
-                             overlay,
-                             name prefix = exemple-,
-                             highlight/.style = {fill = red!15,
-                                                 blend mode = multiply,
-                                                 inner sep = 0pt,
-                                                 fit = ~#1}}}
 \end{Verbatim}
 
-
-\tikzset{mes-options/.style={remember picture, 
-                             overlay,
-                             name prefix = exemple-,
-                             highlight/.style = {fill = red!15,
-                                                 blend mode = multiply,
-                                                 inner sep = 0pt,
-                                                 fit = #1}}}
-
-
-\begin{Verbatim}
-\begin{tikzpicture}[mes-options]
-\node [highlight = (1-1) (1-3)] {} ;
-\node [highlight = (2-1) (2-3)] {} ;
-\node [highlight = (3-1) (3-3)] {} ;
-\end{tikzpicture}
-\end{Verbatim}
-
-\medskip
-On obtient la matrice suivante.
-
-\[\begin{pNiceArray}{ccc}[
-     last-col,
-     code-after = {\begin{tikzpicture}[highlight/.style = {fill = red!15,
-                                                           blend mode = multiply,
-                                                           inner sep = 0pt,
-                                                           fit = #1}]
-                   \node [highlight = (1-1) (1-3)] {} ;
-                   \node [highlight = (2-1) (2-3)] {} ;
-                   \node [highlight = (3-1) (3-3)] {} ;
-                   \end{tikzpicture}}]
+\[\begin{pNiceArray}{ccc}[last-col]
+\CodeBefore [create-cell-nodes]
+  \begin{tikzpicture}
+  \node [highlight = (1-1) (1-3)] {} ;
+  \node [highlight = (2-1) (2-3)] {} ;
+  \node [highlight = (3-1) (3-3)] {} ;
+  \end{tikzpicture}
+\Body
 a & a + b & a + b + c & L_1 \\
 a & a     & a + b     & L_2 \\
 a & a     & a         & L_3
@@ -4901,46 +4835,44 @@ Le résultat peut paraître décevant. On peut l'améliorer en utilisant les «n
 moyens» au lieu des «nœuds normaux».
 
 \begin{Verbatim}
-\begin{tikzpicture}[mes-options, ~emphase#name suffix = -medium@]
-\node [highlight = (1-1) (1-3)] {} ;
-\node [highlight = (2-1) (2-3)] {} ;
-\node [highlight = (3-1) (3-3)] {} ;
-\end{tikzpicture}
+\[\begin{pNiceArray}{ccc}[last-col,create-medium-nodes]
+\CodeBefore [create-cell-nodes]
+  \begin{tikzpicture} ~emphase#[name suffix = -medium]@
+  \node [highlight = (1-1) (1-3)] {} ;
+  \node [highlight = (2-1) (2-3)] {} ;
+  \node [highlight = (3-1) (3-3)] {} ;
+  \end{tikzpicture}
+\Body
+a & a + b & a + b + c & L_1 \\
+a & a     & a + b     & L_2 \\
+a & a     & a         & L_3
+\end{pNiceArray}\]
 \end{Verbatim}
 
-\medskip
-On obtient la matrice suivante.
 
 \[\begin{pNiceArray}{ccc}[last-col,create-medium-nodes]
+\CodeBefore [create-cell-nodes]
+  \begin{tikzpicture} [name suffix = -medium]
+  \node [highlight = (1-1) (1-3)] {} ;
+  \node [highlight = (2-1) (2-3)] {} ;
+  \node [highlight = (3-1) (3-3)] {} ;
+  \end{tikzpicture}
+\Body
 a & a + b & a + b + c & L_1 \\
 a & a     & a + b     & L_2 \\
-a & a     & a         & L_3 \\
-\CodeAfter
-\begin{tikzpicture}[highlight/.style = {fill = red!15,
-                                        blend mode = multiply,
-                                        inner sep = 0pt,
-                                        fit = #1},
-                    name suffix = -medium]
-\node [highlight = (1-1) (1-3)] {} ;
-\node [highlight = (2-1) (2-3)] {} ;
-\node [highlight = (3-1) (3-3)] {} ;
-\end{tikzpicture}
+a & a     & a         & L_3
 \end{pNiceArray}\]
 
                           
 
-\subsection{Utilisation de \textbackslash SubMatrix dans le code-before}
+\subsection{Utilisation de \textbackslash SubMatrix dans le \textbackslash CodeBefore}
 
 Dans l'exemple suivant, on illustre le produit mathématique de deux matrices. 
 
 L'ensemble de la figure est un environnement |{NiceArray}| et les trois paires
-de parenthèses ont été rajoutées avec |\SubMatrix| dans le |code-before|.
+de parenthèses ont été rajoutées avec |\SubMatrix| dans le |\CodeBefore|.
+
 
-Ceux qui sont intéressés par le code correspondant le trouveront dans le fichier
-source de ce document.
-%
-%
-%
 \tikzset{highlight/.style={rectangle,
                            fill=red!15,
                            rounded corners = 0.5 mm, 
@@ -4975,6 +4907,43 @@ source de ce document.
 \end{NiceArray}\]
 
 
+\vspace{1cm}
+\begin{Verbatim}
+\tikzset{highlight/.style={rectangle,
+                           fill=red!15,
+                           rounded corners = 0.5 mm, 
+                           inner sep=1pt,
+                           fit=~#1}}
+\end{Verbatim}
+
+\begin{Verbatim}[formatcom = \small\color{gray}]
+\[\begin{NiceArray}{*{6}{c}~LetterAt{\hspace{6mm}}*{5}{c}}[nullify-dots]
+\CodeBefore [create-cell-nodes]
+  \SubMatrix({2-7}{6-11})
+  \SubMatrix({7-2}{11-6})
+  \SubMatrix({7-7}{11-11})
+  \begin{tikzpicture}
+    \node [highlight = (9-2) (9-6)] { } ; 
+    \node [highlight = (2-9) (6-9)] { } ;
+  \end{tikzpicture}
+\Body
+    &        &        &        &        &        &        &        & \color{blue}\scriptstyle C_j \\
+    &        &        &        &        &        & b_{11} & \Cdots & b_{1j} & \Cdots & b_{1n} \\
+    &        &        &        &        &        & \Vdots &        & \Vdots &        & \Vdots \\
+    &        &        &        &        &        &        &        & b_{kj} \\
+    &        &        &        &        &        &        &        & \Vdots \\
+    &        &        &        &        &        & b_{n1} & \Cdots & b_{nj} & \Cdots & b_{nn} \\[3mm]
+    & a_{11} & \Cdots &        &        & a_{1n} \\
+    & \Vdots &        &        &        & \Vdots &        &        & \Vdots \\
+\color{blue}\scriptstyle L_i 
+    & a_{i1} & \Cdots & a_{ik} & \Cdots & a_{in} & \Cdots &        & c_{ij} \\
+    & \Vdots &        &        &        & \Vdots \\
+    & a_{n1} & \Cdots &        &        & a_{nn}  \\
+\CodeAfter
+\tikz \draw [gray,shorten > = 1mm, shorten < = 1mm] (9-4.north) to [bend left] (4-9.west) ;
+\end{NiceArray}\]
+\end{Verbatim}
+
 
 
 \section*{Autre documentation}
diff --git a/macros/latex/contrib/nicematrix/nicematrix.dtx b/macros/latex/contrib/nicematrix/nicematrix.dtx
index 32206348c0..43fb1accbd 100644
--- a/macros/latex/contrib/nicematrix/nicematrix.dtx
+++ b/macros/latex/contrib/nicematrix/nicematrix.dtx
@@ -15,8 +15,8 @@
 %
 % \fi
 % \iffalse
-\def\myfileversion{5.15b}
-\def\myfiledate{2021/06/05}
+\def\myfileversion{5.16}
+\def\myfiledate{2021/06/20}
 %
 %
 %<*batchfile>
@@ -386,7 +386,9 @@ version 2005/12/01 or later.
 % \end{minipage}
 % 
 % \medskip
-% However, it's also possible to use the tools of \pkg{booktabs}: |\toprule|,
+% However, it's also possible to use the tools of
+% \pkg{booktabs}\footnote{The extension \pkg{booktabs} is \emph{not} loaded
+% by \pkg{nicematrix}.}: |\toprule|,
 % |\bottomrule|, |\midrule|, etc.\par\nobreak
 %
 % \smallskip
@@ -577,11 +579,10 @@ version 2005/12/01 or later.
 % \item the key |borders| provides the ability to draw only some borders of the
 % blocks; the value of that key is a (comma-separated) list of elements covered
 % by |left|, |right|, |top| and |bottom|;
+% \item the keys |t| and |b| fix the base line that will be given to the block
+% when it has a multi-line content (the lines are separated by |\\|);
 % \item \colorbox{yellow!50}{\bfseries New 5.15}\enskip the keys |hvlines| draws
-% all the vertical and horizontal rules in the block;
-% \item \colorbox{yellow!50}{\bfseries New 5.14}\enskip the keys |t| and |b| fix
-% the base line that will be given to the block when it has a multi-line content
-% (the lines are separated by |\\|). 
+% all the vertical and horizontal rules in the block.
 % \end{itemize}
 % 
 % \interitem
@@ -1067,11 +1068,11 @@ version 2005/12/01 or later.
 % \end{NiceTabular}
 %
 % \bigskip
-% \colorbox{yellow!50}{\textbf{New 5.14}}\enskip When the key |corners| is used,
-% \pkg{nicematrix} computes the (empty) corners and these corners will be taken
-% into account by the tools for drawing the rules (the rules won't be drawn in
-% the corners). \emph{Remark}: In the previous versions of \pkg{nicematrix},
-% there was only a key |hvlines-except-corners| (now considered as obsolete).
+% When the key |corners| is used, \pkg{nicematrix} computes the (empty) corners
+% and these corners will be taken into account by the tools for drawing the
+% rules (the rules won't be drawn in the corners). \emph{Remark}: In the
+% previous versions of \pkg{nicematrix}, there was only a key
+% |hvlines-except-corners| (now considered as obsolete).
 %
 % \bigskip
 % \begin{BVerbatim}[boxwidth=11cm,baseline=c]
@@ -3252,7 +3253,7 @@ version 2005/12/01 or later.
 % exists) has also the number~$0$.}. Of course, the user must not change the
 % value of these counters which are used internally by \pkg{nicematrix}.
 %
-% In the |code-before| (cf. p. \pageref{code-before}) and in the |\CodeAfter|
+% In the |\CodeBefore| (cf. p. \pageref{code-before}) and in the |\CodeAfter|
 % (cf. p. \pageref{code-after}), |iRow| represents the total number of rows
 % (excepted the potential exterior rows) and |jCol| represents the total number
 % of columns (excepted the potential exterior columns).
@@ -3489,26 +3490,26 @@ version 2005/12/01 or later.
 % In the following example, we have underlined all the nodes of the matrix (we
 % explain below the technic used : cf. p. \pageref{highlight}). 
 %
-% \[\begin{pNiceMatrix}[
-%  code-after = {\begin{tikzpicture}
-%                   [every node/.style = {blend mode = multiply,
-%                                         fill = red!15,
-%                                         inner sep = 0 pt }]
-%                \node [fit = (1-1)] {} ;
-%                \node [fit = (1-3)] {} ;
-%                \node [fit = (2-2)] {} ;
-%                \node [fit = (3-1)] {} ;
-%                \node [fit = (3-3)] {} ;
-%                \node [fit = (1-2)] {} ;
-%                \node [fit = (2-1)] {} ;
-%                \node [fit = (2-3)] {} ;
-%                \node [fit = (3-2)] {} ;
-%                \end{tikzpicture}}]
+% 
+% \[\begin{pNiceMatrix}
+% \CodeBefore [create-cell-nodes]
+%    \begin{tikzpicture}%
+%      [every node/.style = { inner sep = 0 pt , fill = red!15 }]
+%    \node [fit = (1-1)] {} ;
+%    \node [fit = (1-3)] {} ;
+%    \node [fit = (2-2)] {} ;
+%    \node [fit = (3-1)] {} ;
+%    \node [fit = (3-3)] {} ;
+%    \node [fit = (1-2)] {} ;
+%    \node [fit = (2-1)] {} ;
+%    \node [fit = (2-3)] {} ;
+%    \node [fit = (3-2)] {} ;
+%    \end{tikzpicture}
+% \Body
 % a & a + b & a + b + c \\
 % a & a     & a + b  \\
 % a & a     & a 
 % \end{pNiceMatrix}\]
-% 
 %
 % 
 % \subsection{The ``medium nodes'' and the ``large nodes''}
@@ -3529,23 +3530,22 @@ version 2005/12/01 or later.
 % ``|-medium|'' to the names of the ``normal nodes''. In the following example,
 % we have underlined the ``medium nodes''. We consider that this example is
 % self-explanatory.
-% \[\begin{pNiceMatrix}[
-%  create-medium-nodes,
-%  code-after = {\begin{tikzpicture}
-%                   [every node/.style = {fill = red!15,
-%                                         blend mode = multiply,
-%                                         inner sep = 0pt},
-%                    name suffix = -medium]
-%                \node [fit = (1-1)] {} ;
-%                \node [fit = (1-2)] {} ;
-%                \node [fit = (1-3)] {} ;
-%                \node [fit = (2-1)] {} ;
-%                \node [fit = (2-2)] {} ;
-%                \node [fit = (2-3)] {} ;
-%                \node [fit = (3-1)] {} ;
-%                \node [fit = (3-2)] {} ;
-%                \node [fit = (3-3)] {} ;
-%                \end{tikzpicture}}]
+% \[\begin{pNiceMatrix}[create-medium-nodes]
+% \CodeBefore [create-cell-nodes]
+%    \begin{tikzpicture} 
+%       [every node/.style = {fill = red!15, inner sep = 0 pt},
+%        name suffix = -medium]
+%    \node [fit = (1-1)] {} ;
+%    \node [fit = (1-2)] {} ;
+%    \node [fit = (1-3)] {} ;
+%    \node [fit = (2-1)] {} ;
+%    \node [fit = (2-2)] {} ;
+%    \node [fit = (2-3)] {} ;
+%    \node [fit = (3-1)] {} ;
+%    \node [fit = (3-2)] {} ;
+%    \node [fit = (3-3)] {} ;
+% \end{tikzpicture}
+% \Body
 % a & a + b & a + b + c \\
 % a & a     & a + b  \\
 % a & a     & a 
@@ -3558,27 +3558,27 @@ version 2005/12/01 or later.
 % we have underlined the ``large nodes''. We consider that this example is
 % self-explanatory.\footnote{There is no ``large nodes'' created in the exterior
 % rows and columns (for these rows and columns, cf. p.~\pageref{exterior}).}
-%
-% \[\begin{pNiceMatrix}[
-%  create-large-nodes,
-%  code-after = {\begin{tikzpicture}
-%                   [every node/.style = {blend mode = multiply,
-%                                         inner sep = 0pt},
-%                    name suffix = -large]
-%                \node [fit = (1-1),fill = red!15] {} ;
-%                \node [fit = (1-3),fill = red!15] {} ;
-%                \node [fit = (2-2),fill = red!15] {} ;
-%                \node [fit = (3-1),fill = red!15] {} ;
-%                \node [fit = (3-3),fill = red!15] {} ;
-%                \node [fit = (1-2),fill = blue!15] {} ;
-%                \node [fit = (2-1),fill = blue!15] {} ;
-%                \node [fit = (2-3),fill = blue!15] {} ;
-%                \node [fit = (3-2),fill = blue!15] {} ;
-%                \end{tikzpicture}}]
+% \[\begin{pNiceMatrix}[create-large-nodes]
+% \CodeBefore [create-cell-nodes]
+%    \begin{tikzpicture}
+%       [every node/.style = { inner sep = 0 pt} ,
+%        name suffix = -large]
+%    \node [fit = (1-1),fill = red!15] {} ;
+%    \node [fit = (1-3),fill = red!15] {} ;
+%    \node [fit = (2-2),fill = red!15] {} ;
+%    \node [fit = (3-1),fill = red!15] {} ;
+%    \node [fit = (3-3),fill = red!15] {} ;
+%    \node [fit = (1-2),fill = blue!15] {} ;
+%    \node [fit = (2-1),fill = blue!15] {} ;
+%    \node [fit = (2-3),fill = blue!15] {} ;
+%    \node [fit = (3-2),fill = blue!15] {} ;
+%    \end{tikzpicture}
+% \Body
 % a & a + b & a + b + c \\
 % a & a     & a + b  \\
 % a & a     & a 
 % \end{pNiceMatrix}\]
+%
 % 
 %
 % \medskip
@@ -3591,26 +3591,27 @@ version 2005/12/01 or later.
 % value is given, the default value is used, which is |\arraycolsep| (by
 % default: 5~pt). There is also an option |margin| to fix both |left-margin| and
 % |right-margin| to the same value.}
-% \[\begin{pNiceMatrix}[
-%  create-large-nodes,left-margin,right-margin,
-%  code-after = {\begin{tikzpicture}
-%                   [every node/.style = {blend mode = multiply,
-%                                         inner sep = 0pt},
-%                    name suffix = -large]
-%                \node [fit = (1-1),fill = red!15] {} ;
-%                \node [fit = (1-3),fill = red!15] {} ;
-%                \node [fit = (2-2),fill = red!15] {} ;
-%                \node [fit = (3-1),fill = red!15] {} ;
-%                \node [fit = (3-3),fill = red!15] {} ;
-%                \node [fit = (1-2),fill = blue!15] {} ;
-%                \node [fit = (2-1),fill = blue!15] {} ;
-%                \node [fit = (2-3),fill = blue!15] {} ;
-%                \node [fit = (3-2),fill = blue!15] {} ;
-%                \end{tikzpicture}}]
+% \[\begin{pNiceMatrix}[create-large-nodes,left-margin,right-margin]
+% \CodeBefore [create-cell-nodes]
+%     \begin{tikzpicture}
+%        [every node/.style = {inner sep = 0 pt},
+%         name suffix = -large]
+%     \node [fit = (1-1),fill = red!15] {} ;
+%     \node [fit = (1-3),fill = red!15] {} ;
+%     \node [fit = (2-2),fill = red!15] {} ;
+%     \node [fit = (3-1),fill = red!15] {} ;
+%     \node [fit = (3-3),fill = red!15] {} ;
+%     \node [fit = (1-2),fill = blue!15] {} ;
+%     \node [fit = (2-1),fill = blue!15] {} ;
+%     \node [fit = (2-3),fill = blue!15] {} ;
+%     \node [fit = (3-2),fill = blue!15] {} ;
+%     \end{tikzpicture}
+% \Body
 % a & a + b & a + b + c \\
 % a & a     & a + b  \\
 % a & a     & a 
 % \end{pNiceMatrix}\]
+%
 % 
 % \medskip
 % It's also possible to add more space on both side of the array with the
@@ -3618,22 +3619,22 @@ version 2005/12/01 or later.
 % incorporated in the ``large nodes''. It's possible to fix both values with the
 % option |extra-margin| and, in the following example, we use |extra-margin|
 % with the value $3$~pt.
-% \[\begin{pNiceMatrix}[
-%  create-large-nodes,margin,extra-margin=3pt,
-%  code-after = {\begin{tikzpicture}
-%                   [every node/.style = {blend mode = multiply,
-%                                         inner sep = 0 pt},
-%                    name suffix = -large]
-%                \node [fit = (1-1),fill = red!15] {} ;
-%                \node [fit = (1-3),fill = red!15] {} ;
-%                \node [fit = (2-2),fill = red!15] {} ;
-%                \node [fit = (3-1),fill = red!15] {} ;
-%                \node [fit = (3-3),fill = red!15] {} ;
-%                \node [fit = (1-2),fill = blue!15] {} ;
-%                \node [fit = (2-1),fill = blue!15] {} ;
-%                \node [fit = (2-3),fill = blue!15] {} ;
-%                \node [fit = (3-2),fill = blue!15] {} ;
-%                \end{tikzpicture}}]
+% \[\begin{pNiceMatrix}[create-large-nodes,left-margin,right-margin,extra-right-margin=3pt,extra-left-margin=3pt]
+% \CodeBefore [create-cell-nodes]
+%     \begin{tikzpicture}
+%        [every node/.style = {inner sep = 0 pt},
+%         name suffix = -large]
+%     \node [fit = (1-1),fill = red!15] {} ;
+%     \node [fit = (1-3),fill = red!15] {} ;
+%     \node [fit = (2-2),fill = red!15] {} ;
+%     \node [fit = (3-1),fill = red!15] {} ;
+%     \node [fit = (3-3),fill = red!15] {} ;
+%     \node [fit = (1-2),fill = blue!15] {} ;
+%     \node [fit = (2-1),fill = blue!15] {} ;
+%     \node [fit = (2-3),fill = blue!15] {} ;
+%     \node [fit = (3-2),fill = blue!15] {} ;
+%     \end{tikzpicture}
+% \Body
 % a & a + b & a + b + c \\
 % a & a     & a + b  \\
 % a & a     & a 
@@ -3693,22 +3694,22 @@ version 2005/12/01 or later.
 % \hspace{1.5cm}
 % \begin{scope}
 % \large
-% \begin{NiceTabular}[c]{wl{2cm}ll}[hvlines,
-%  create-large-nodes,
-%  code-after = {\begin{tikzpicture}
-%                   [every node/.style = {blend mode = multiply,
-%                                         inner sep = 0 pt},
-%                    name suffix = -large]
-%                \node [fit = (1-1),fill = red!15] {} ;
-%                \node [fit = (1-3),fill = red!15] {} ;
-%                \node [fit = (2-2),fill = red!15] {} ;
-%                \node [fit = (3-1),fill = red!15] {} ;
-%                \node [fit = (3-3),fill = red!15] {} ;
-%                \node [fit = (1-2),fill = blue!15] {} ;
-%                \node [fit = (2-1),fill = blue!15] {} ;
-%                \node [fit = (2-3),fill = blue!15] {} ;
-%                \node [fit = (3-2),fill = blue!15] {} ;
-%                \end{tikzpicture}}]
+% \begin{NiceTabular}[c]{w{l}{2cm}ll}[hvlines,create-large-nodes]
+% \CodeBefore [create-cell-nodes]
+%     \begin{tikzpicture}
+%        [every node/.style = {inner sep = 0 pt},
+%         name suffix = -large]
+%     \node [fit = (1-1),fill = red!15] {} ;
+%     \node [fit = (1-3),fill = red!15] {} ;
+%     \node [fit = (2-2),fill = red!15] {} ;
+%     \node [fit = (3-1),fill = red!15] {} ;
+%     \node [fit = (3-3),fill = red!15] {} ;
+%     \node [fit = (1-2),fill = blue!15] {} ;
+%     \node [fit = (2-1),fill = blue!15] {} ;
+%     \node [fit = (2-3),fill = blue!15] {} ;
+%     \node [fit = (3-2),fill = blue!15] {} ;
+%     \end{tikzpicture}
+% \Body
 % fraise & amande & abricot \\
 % prune & pêche & poire  \\[1ex]
 % noix & noisette & brugnon
@@ -3716,7 +3717,15 @@ version 2005/12/01 or later.
 % \end{scope}
 %
 %
+% \vspace{1cm}
+% The nodes we have described are not available by default in the |\CodeBefore|
+% (described p.~\pageref{code-before}).\par\nobreak
 %
+% \colorbox{yellow!50}{\textbf{New 5.16}}\enskip It's possible to have these
+% nodes available in the |\CodeBefore| by using the key |create-cell-nodes| of
+% the keyword |\CodeBefore| (in that case, the nodes are created first before
+% the construction of the array by using informations written on the |aux| file
+% and created a second time during the contruction of the array itself).
 % 
 % \subsection{The nodes which indicate the position of the rules}
 %
@@ -3725,10 +3734,8 @@ version 2005/12/01 or later.
 % the classical prefix) at the intersection of the horizontal rule of number~$i$
 % and the vertical rule of number~$i$ (more specifically the potential position
 % of those rules because maybe there are not actually drawn). The last node has
-% also an alias called |last|.
-% 
-% \colorbox{yellow!50}{\textbf{New 5.14}}\enskip There is also a node called
-% $i$|.5| midway between the node $i$ and the node $i+1$. 
+% also an alias called |last|. There is also a node called $i$|.5| midway
+% between the node $i$ and the node $i+1$.
 %
 % These nodes are available in the |\CodeBefore| and the |\CodeAfter|.
 % 
@@ -4690,9 +4697,14 @@ version 2005/12/01 or later.
 % \usetikzlibrary{fit}
 % \end{verbatim}
 %
+% \medskip 
+% We create a rectangular Tikz node which encompasses the nodes of the second
+% row by using the tools of the Tikz library \pkg{fit}. Those nodes are not
+% available by default in the |\CodeBefore| (for efficiency). We have to require
+% their creation with the key |create-cell-nodes| of the keyword |\CodeBefore|.
+%
 % \tikzset{highlight/.style={rectangle,
 %                            fill=red!15,
-%                            blend mode = multiply, 
 %                            rounded corners = 0.5 mm, 
 %                            inner sep=1pt,
 %                            fit = #1}}
@@ -4701,120 +4713,58 @@ version 2005/12/01 or later.
 % \begin{Verbatim}
 % \tikzset{highlight/.style={rectangle,
 %                            fill=red!15,
-%                            ~emphase#blend mode = multiply@,
 %                            rounded corners = 0.5 mm, 
 %                            inner sep=1pt,
-%                            fit = ~#1}}
+%                            fit=~#1}}
 %
-% 
 % $\begin{bNiceMatrix}
+% ~emphase#\CodeBefore [create-cell-nodes] @
+% ~emphase#  \tikz \node [highlight = (2-1) (2-3)] {} ; @
+% ~emphase# \Body @
 % 0 & \Cdots & 0 \\
 % 1 & \Cdots & 1 \\
 % 0 & \Cdots & 0 \\
-% ~emphase#\CodeAfter \tikz \node [highlight = (2-1) (2-3)] {} ;@
 % \end{bNiceMatrix}$
 % \end{Verbatim}
 % \[\begin{bNiceMatrix}
+% \CodeBefore [create-cell-nodes] 
+%   \tikz \node [highlight = (2-1) (2-3)] {} ;
+% \Body
 % 0 & \Cdots & 0 \\
 % 1 & \Cdots & 1 \\
 % 0 & \Cdots & 0 \\
-% \CodeAfter \tikz \node [highlight = (2-1) (2-3)] {} ; 
 % \end{bNiceMatrix}\]
 %
-%
-%
-% \vspace{1cm} 
-% We recall that, for a rectangle of merged cells (with the command |\Block|), a
-% Tikz node is created for the set of merged cells with the name
-% $i$|-|$j$-|block| where $i$ and $j$ are the number of the row and the number
-% of the column of the upper left cell (where the command |\Block| has been
-% issued). If the user has required the creation of the |medium| nodes, a node
-% of this type is also created with a name suffixed by |-medium|.
-%
-% \medskip
-% \begin{BVerbatim}[baseline=c,boxwidth=11.6cm]
-% $\begin{pNiceMatrix}[margin,create-medium-nodes]
-%   \Block{3-3}<\Large>{A} & & & 0 \\
-%   & \hspace*{1cm} & & \Vdots \\
-%   & & & 0 \\
-%   0 & \Cdots& 0 & 0
-% \CodeAfter
-%   \tikz \node [~emphase#highlight = (1-1-block-medium)@] {} ;
-% \end{pNiceMatrix}$
-% \end{BVerbatim}
-% $\begin{pNiceMatrix}[margin,create-medium-nodes]
-% \Block{3-3}<\Large>{A} & & & 0 \\
-% & \hspace*{1cm} & & \Vdots \\
-% & & & 0 \\
-% 0 & \Cdots& 0 & 0
-% \CodeAfter
-%   \tikz \node [highlight = (1-1-block-medium)] {} ;
-% \end{pNiceMatrix}$
-%
 % 
 % \vspace{1cm}
-% Consider now the following matrix which we have named |example|.
+% We consider now the following matrix. If we want to highlight each row of
+% this matrix, we can use the previous technique three times.
 %
-% \medskip
 % \begin{Verbatim}
-% $\begin{pNiceArray}{ccc}[~emphase#name=example@,last-col,create-medium-nodes]
-% a & a + b & a + b + c & L_1 \\
-% a & a     & a + b     & L_2 \\
-% a & a     & a         & L_3
-% \end{pNiceArray}$
-% \end{Verbatim}
-%                           
 % \[\begin{pNiceArray}{ccc}[last-col]
+% \CodeBefore [create-cell-nodes]
+%   \begin{tikzpicture}
+% ~emphase#  \node [highlight = (1-1) (1-3)] {} ;@
+% ~emphase#  \node [highlight = (2-1) (2-3)] {} ;@
+% ~emphase#  \node [highlight = (3-1) (3-3)] {} ;@
+%   \end{tikzpicture}
+% \Body
 % a & a + b & a + b + c & L_1 \\
 % a & a     & a + b     & L_2 \\
 % a & a     & a         & L_3
 % \end{pNiceArray}\]
-% 
-% \bigskip
-% If we want to highlight each row of this matrix, we can use the previous
-% technique three times. 
-%
-% \begin{Verbatim}
-% \tikzset{mes-options/.style={remember picture, 
-%                              overlay,
-%                              name prefix = exemple-,
-%                              highlight/.style = {fill = red!15,
-%                                                  blend mode = multiply,
-%                                                  inner sep = 0pt,
-%                                                  fit = ~#1}}}
-% \end{Verbatim}
-% 
-%
-% \tikzset{mes-options/.style={remember picture, 
-%                              overlay,
-%                              name prefix = exemple-,
-%                              highlight/.style = {fill = red!15,
-%                                                  blend mode = multiply,
-%                                                  inner sep = 0pt,
-%                                                  fit = #1}}}
-%
-% \begin{Verbatim}
-% \begin{tikzpicture}[mes-options]
-% \node [highlight = (1-1) (1-3)] {} ;
-% \node [highlight = (2-1) (2-3)] {} ;
-% \node [highlight = (3-1) (3-3)] {} ;
-% \end{tikzpicture}
 % \end{Verbatim}
 %
 %
-% \medskip
-% We obtain the following matrix.
-% 
-% \[\begin{pNiceArray}{ccc}[
-%      last-col,
-%      code-after = {\begin{tikzpicture}[every node/.style = {fill = red!15,
-%                                                             blend mode = multiply,
-%                                                             inner sep = 0pt}]
-%                    \node [fit = (1-1) (1-3)] {} ;
-%                    \node [fit = (2-1) (2-3)] {} ;
-%                    \node [fit = (3-1) (3-3)] {} ;
-%                    \end{tikzpicture}}]
-% a & a + b & a + b + c & L_1\\
+% \[\begin{pNiceArray}{ccc}[last-col]
+% \CodeBefore [create-cell-nodes]
+%   \begin{tikzpicture}
+%   \node [highlight = (1-1) (1-3)] {} ;
+%   \node [highlight = (2-1) (2-3)] {} ;
+%   \node [highlight = (3-1) (3-3)] {} ;
+%   \end{tikzpicture}
+% \Body
+% a & a + b & a + b + c & L_1 \\
 % a & a     & a + b     & L_2 \\
 % a & a     & a         & L_3
 % \end{pNiceArray}\]
@@ -4824,28 +4774,29 @@ version 2005/12/01 or later.
 % nodes'' instead of the ``normal nodes''. 
 %
 % \begin{Verbatim}
-% \begin{tikzpicture}[mes-options, ~emphase#name suffix = -medium@]
-% \node [highlight = (1-1) (1-3)] {} ;
-% \node [highlight = (2-1) (2-3)] {} ;
-% \node [highlight = (3-1) (3-3)] {} ;
-% \end{tikzpicture}
+% \[\begin{pNiceArray}{ccc}[last-col,create-medium-nodes]
+% \CodeBefore [create-cell-nodes]
+%   \begin{tikzpicture} ~emphase#[name suffix = -medium]@
+%   \node [highlight = (1-1) (1-3)] {} ;
+%   \node [highlight = (2-1) (2-3)] {} ;
+%   \node [highlight = (3-1) (3-3)] {} ;
+%   \end{tikzpicture}
+% \Body
+% a & a + b & a + b + c & L_1 \\
+% a & a     & a + b     & L_2 \\
+% a & a     & a         & L_3
+% \end{pNiceArray}\]
 % \end{Verbatim}
 %
-% \medskip
-% We obtain the following matrix.
-% 
-% \[\begin{pNiceArray}{ccc}[
-%      last-col,
-%      create-medium-nodes,
-%      code-after = {\begin{tikzpicture}[highlight/.style = {fill = red!15,
-%                                                            blend mode = multiply,
-%                                                            inner sep = 0pt,
-%                                                            fit = #1},
-%                                        name suffix = -medium]
-%                    \node [highlight = (1-1) (1-3)] {} ;
-%                    \node [highlight = (2-1) (2-3)] {} ;
-%                    \node [highlight = (3-1) (3-3)] {} ;
-%                    \end{tikzpicture}}]
+% 
+%\[\begin{pNiceArray}{ccc}[last-col,create-medium-nodes]
+% \CodeBefore [create-cell-nodes]
+%   \begin{tikzpicture} [name suffix = -medium]
+%   \node [highlight = (1-1) (1-3)] {} ;
+%   \node [highlight = (2-1) (2-3)] {} ;
+%   \node [highlight = (3-1) (3-3)] {} ;
+%   \end{tikzpicture}
+% \Body
 % a & a + b & a + b + c & L_1 \\
 % a & a     & a + b     & L_2 \\
 % a & a     & a         & L_3
@@ -4858,10 +4809,8 @@ version 2005/12/01 or later.
 % matrices. 
 %
 % The whole figure is an environment |{NiceArray}| and the three pairs of
-% parenthesis have been added with |\SubMatrix| in the |code-before|.
+% parenthesis have been added with |\SubMatrix| in the |\CodeBefore|.
 %
-% You will find the LaTeX code of that figure in the source file of this
-% document.
 % \tikzset{highlight/.style={rectangle,
 %                            fill=red!15,
 %                            rounded corners = 0.5 mm, 
@@ -4893,6 +4842,44 @@ version 2005/12/01 or later.
 % \tikz \draw [gray,shorten > = 1mm, shorten < = 1mm] (9-4.north) to [bend left] (4-9.west) ;
 % \end{NiceArray}\]
 %
+%
+% \vspace{1cm}
+% \begin{Verbatim}
+% \tikzset{highlight/.style={rectangle,
+%                            fill=red!15,
+%                            rounded corners = 0.5 mm, 
+%                            inner sep=1pt,
+%                            fit=~#1}}
+% \end{Verbatim}
+%
+% \begin{Verbatim}[formatcom = \small\color{gray}]
+% \[\begin{NiceArray}{*{6}{c}~LetterAt{\hspace{6mm}}*{5}{c}}[nullify-dots]
+% \CodeBefore [create-cell-nodes]
+%   \SubMatrix({2-7}{6-11})
+%   \SubMatrix({7-2}{11-6})
+%   \SubMatrix({7-7}{11-11})
+%   \begin{tikzpicture}
+%     \node [highlight = (9-2) (9-6)] { } ; 
+%     \node [highlight = (2-9) (6-9)] { } ;
+%   \end{tikzpicture}
+% \Body
+%     &        &        &        &        &        &        &        & \color{blue}\scriptstyle C_j \\
+%     &        &        &        &        &        & b_{11} & \Cdots & b_{1j} & \Cdots & b_{1n} \\
+%     &        &        &        &        &        & \Vdots &        & \Vdots &        & \Vdots \\
+%     &        &        &        &        &        &        &        & b_{kj} \\
+%     &        &        &        &        &        &        &        & \Vdots \\
+%     &        &        &        &        &        & b_{n1} & \Cdots & b_{nj} & \Cdots & b_{nn} \\[3mm]
+%     & a_{11} & \Cdots &        &        & a_{1n} \\
+%     & \Vdots &        &        &        & \Vdots &        &        & \Vdots \\
+% \color{blue}\scriptstyle L_i 
+%     & a_{i1} & \Cdots & a_{ik} & \Cdots & a_{in} & \Cdots &        & c_{ij} \\
+%     & \Vdots &        &        &        & \Vdots \\
+%     & a_{n1} & \Cdots &        &        & a_{nn}  \\
+% \CodeAfter
+% \tikz \draw [gray,shorten > = 1mm, shorten < = 1mm] (9-4.north) to [bend left] (4-9.west) ;
+% \end{NiceArray}\]
+% \end{Verbatim}
+%
 % 
 %\section{Implementation}
 %
@@ -5048,10 +5035,38 @@ version 2005/12/01 or later.
 \cs_if_exist:NT \rvtx@ifformat@geq { \bool_set_true:N \c_@@_revtex_bool }
 %    \end{macrocode}
 %
-%
+% \bigskip
 %    \begin{macrocode}
 \cs_generate_variant:Nn \tl_if_single_token_p:n { V }
 %    \end{macrocode}
+%
+% \bigskip
+% The following regex will be used to modify the preamble of the array when the
+% key |colortbl-like| is used.
+%    \begin{macrocode}
+\regex_const:Nn \c_@@_columncolor_regex { \c { columncolor } } 
+%    \end{macrocode}
+% 
+% \bigskip
+% If the final user uses \pkg{nicematrix}, PGF/Tikz will write instruction
+% |\pgfsyspdfmark| in the |aux| file. If he changes its mind and no longer loads
+% \pkg{nicematrix}, an error may occur at the next compilation because of
+% remanent instructions |\pgfsyspdfmark| in the |aux| file. With the following
+% code, we try to avoid that situation.
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_provide_pgfsyspdfmark:
+  {
+    \iow_now:Nn \@mainaux 
+      {
+        \ExplSyntaxOn
+        \cs_if_free:NT \pgfsyspdfmark
+          { \cs_set_eq:NN \pgfsyspdfmark \@gobblethree }
+        \ExplSyntaxOff
+      }
+    \cs_gset_eq:NN \@@_provide_pgfsyspdfmark: \prg_do_nothing:
+  }
+%    \end{macrocode}
+%
 % 
 % \bigskip
 % We define a command |\iddots| similar to |\ddots| ($\ddots$) but with dots
@@ -5342,53 +5357,33 @@ version 2005/12/01 or later.
 % |\c_@@_table_print_tl| when the version of \pkg{siunitx} is prior to 3.0. The
 % command |\@@_adapt_S_column| is used in the environment |{NiceArrayWithDelims}|.
 %    \begin{macrocode}
-\cs_set_protected:Npn \@@_adapt_S_column:
+\AtBeginDocument
   {
-    \bool_if:NT \c_@@_siunitx_loaded_bool
-      { 
-        \group_begin:
-        \@temptokena = { }
-        \cs_set_eq:NN \NC@find \prg_do_nothing:
-        \NC@rewrite@S { }
-        \tl_gset:NV \g_tmpa_tl \@temptokena 
-        \group_end:
-        \tl_new:N \c_@@_table_collect_begin_tl
-        \tl_set:Nx \l_tmpa_tl { \tl_item:Nn \g_tmpa_tl 2 }
-        \tl_gset:Nx \c_@@_table_collect_begin_tl { \tl_item:Nn \l_tmpa_tl 1 }
-        \tl_new:N \c_@@_table_print_tl
-        \tl_gset:Nx \c_@@_table_print_tl { \tl_item:Nn \g_tmpa_tl { -1 } }
-        \cs_gset_eq:NN \@@_adapt_S_column: \prg_do_nothing:
+    \cs_set_eq:NN \@@_adapt_S_column: \prg_do_nothing:
+    \bool_lazy_and:nnT 
+      { \c_@@_siunitx_loaded_bool }
+      { ! \cs_if_exist_p:N \siunitx_cell_begin:w }
+      {
+        \cs_set_protected:Npn \@@_adapt_S_column:
+          {
+            \group_begin:
+            \@temptokena = { }
+            \cs_set_eq:NN \NC@find \prg_do_nothing:
+            \NC@rewrite@S { }
+            \tl_gset:NV \g_tmpa_tl \@temptokena 
+            \group_end:
+            \tl_new:N \c_@@_table_collect_begin_tl
+            \tl_set:Nx \l_tmpa_tl { \tl_item:Nn \g_tmpa_tl 2 }
+            \tl_gset:Nx \c_@@_table_collect_begin_tl { \tl_item:Nn \l_tmpa_tl 1 }
+            \tl_new:N \c_@@_table_print_tl
+            \tl_gset:Nx \c_@@_table_print_tl { \tl_item:Nn \g_tmpa_tl { -1 } }
+            \cs_gset_eq:NN \@@_adapt_S_column: \prg_do_nothing:
+          }
       }
   }
 %    \end{macrocode}
 %
 %
-% \bigskip
-% The following regex will be used to modify the preamble of the array when the
-% key |colortbl-like| is used.
-%    \begin{macrocode}
-\regex_const:Nn \c_@@_columncolor_regex { \c { columncolor } } 
-%    \end{macrocode}
-% 
-% \bigskip
-% If the final user uses \pkg{nicematrix}, PGF/Tikz will write instruction
-% |\pgfsyspdfmark| in the |aux| file. If he changes its mind and no longer loads
-% \pkg{nicematrix}, an error may occur at the next compilation because of
-% remanent instructions |\pgfsyspdfmark| in the |aux| file. With the following
-% code, we try to avoid that situation.
-%    \begin{macrocode}
-\cs_new_protected:Npn \@@_provide_pgfsyspdfmark:
-  {
-    \iow_now:Nn \@mainaux 
-      {
-        \ExplSyntaxOn
-        \cs_if_free:NT \pgfsyspdfmark
-          { \cs_set_eq:NN \pgfsyspdfmark \@gobblethree }
-        \ExplSyntaxOff
-      }
-    \cs_gset_eq:NN \@@_provide_pgfsyspdfmark: \prg_do_nothing:
-  }
-%    \end{macrocode}
 %
 % \bigskip
 % \subsection*{Parameters}
@@ -5550,6 +5545,15 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \bigskip
+% We will write in |\g_@@_aux_tl| all the instructions that we have to write on
+% the |aux| file for the current environment. The contain of that token list
+% will be written on the |aux| file at the end of the environment (in an
+% instruction |\tl_gset:cn { c_@@_ \int_use:N \g_@@_env_int _ tl }|).
+%    \begin{macrocode}
+\tl_new:N \g_@@_aux_tl
+%    \end{macrocode}  
+% 
+% \bigskip
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_test_if_math_mode:
   { 
@@ -5795,6 +5799,17 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \medskip
+% The sequence |\g_@@_multicolumn_cells_seq| will contain the list of the cells
+% of the array where a command |\multicolumn{|$n$|}{...}{...}| with $n>1$ is
+% issued. In |\g_@@_multicolumn_sizes_seq|, the ``sizes'' (that is to say the
+% values of $n$) correspondant will be stored. These lists will be used for the
+% creation of the ``medium nodes'' (if they are created). 
+%    \begin{macrocode}
+\seq_new:N \g_@@_multicolumn_cells_seq
+\seq_new:N \g_@@_multicolumn_sizes_seq
+%    \end{macrocode}
+%
+% \medskip
 % The following counters will be used when searching the extremities of a dotted
 % line (we need these counters because of the potential ``open'' lines in the
 % |\SubMatrix|---the |\SubMatrix| in the |code-before|).
@@ -5854,7 +5869,7 @@ version 2005/12/01 or later.
 % \medskip
 % The parameters of position of the label of a block. For the horizontal
 % position, the possible values are |c|, |r| and |l|. For the vertical position,
-% the possible values are |c|, |t| and |b|. Of course, it would be intesting to
+% the possible values are |c|, |t| and |b|. Of course, it would be interesting to
 % program a key |T| and a key |B|.
 %    \begin{macrocode}
 \tl_new:N \l_@@_hpos_of_block_tl
@@ -7075,6 +7090,8 @@ version 2005/12/01 or later.
     \endpgfpicture
   }
 %    \end{macrocode}
+% Remark: If the key |recreate-cell-nodes| of the |\CodeBefore| is used, then we
+% will add some lines to that command.
 % 
 %
 % \interitem
@@ -7244,7 +7261,7 @@ version 2005/12/01 or later.
 % \medskip
 % As its name says, the following command is a patch for the command
 % |\@@_node_for_cell:|. This patch will be appended on the left of 
-% |\@@_noce_for_the_cell:| when the construction of the cell nodes (of the forme
+% |\@@_node_for_the_cell:| when the construction of the cell nodes (of the form
 % |(i-j)|) in the |\CodeBefore| is required.
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_patch_node_for_cell:n #1
@@ -7278,6 +7295,8 @@ version 2005/12/01 or later.
   } 
 %    \end{macrocode}
 %
+% \bigskip
+% We have no explanation for the different behaviour between the TeX engines...
 %    \begin{macrocode}
 \bool_lazy_or:nnTF \sys_if_engine_xetex_p: \sys_if_output_dvi_p:
   {
@@ -7546,12 +7565,6 @@ version 2005/12/01 or later.
     \bool_if:NT \c_@@_booktabs_loaded_bool
       { \tl_put_left:Nn \@BTnormal \@@_create_row_node: }
     \box_clear_new:N \l_@@_cell_box
-    \cs_if_exist:NT \theiRow
-      { \int_set_eq:NN \l_@@_old_iRow_int \c@iRow }
-    \int_gzero_new:N \c@iRow
-    \cs_if_exist:NT \thejCol
-      { \int_set_eq:NN \l_@@_old_jCol_int \c@jCol }
-    \int_gzero_new:N \c@jCol
     \normalbaselines
 %    \end{macrocode}
 % If the option |small| is used, we have to do some tuning. In particular, we
@@ -7567,6 +7580,17 @@ version 2005/12/01 or later.
       }
 %    \end{macrocode}
 %
+% \bigskip
+%    \begin{macrocode}
+    \bool_if:NT \g_@@_recreate_cell_nodes_bool
+      {
+        \tl_put_right:Nn \@@_begin_of_row:
+          {
+            \pgfsys@markposition 
+              { \@@_env: - row - \int_use:N \c@iRow - base } 
+          }
+      }
+%    \end{macrocode}
 % 
 % \bigskip
 % The environment |{array}| uses internally the command |\ialign|. We change the
@@ -7662,8 +7686,8 @@ version 2005/12/01 or later.
 % values of $n$) correspondant will be stored. These lists will be used for the
 % creation of the ``medium nodes'' (if they are created). 
 %    \begin{macrocode}
-    \seq_gclear_new:N \g_@@_multicolumn_cells_seq
-    \seq_gclear_new:N \g_@@_multicolumn_sizes_seq
+    \seq_gclear:N \g_@@_multicolumn_cells_seq
+    \seq_gclear:N \g_@@_multicolumn_sizes_seq
 %    \end{macrocode}
 % 
 %
@@ -7724,18 +7748,45 @@ version 2005/12/01 or later.
 %
 %
 % \bigskip
+% The command |\@@_pre_array:| will be executed after analyse of the keys of the
+% environment. 
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_pre_array:
   {
-    \seq_gclear:N \g_@@_submatrix_seq
-    \bool_if:NT \l_@@_code_before_bool \@@_exec_code_before:
 %    \end{macrocode}
 % 
-% A value of $-1$ for the counter |\l_@@_last_row_int| means that the user has
-% used the option |last-row| without value, that is to say without specifying
-% the number of that last row. In this case, we try to read that value from the
-% |aux| file (if it has been written on a previous run). 
+%    \begin{macrocode}
+    \cs_if_exist:NT \theiRow { \int_set_eq:NN \l_@@_old_iRow_int \c@iRow }
+    \int_gzero_new:N \c@iRow
+    \cs_if_exist:NT \thejCol { \int_set_eq:NN \l_@@_old_jCol_int \c@jCol }
+    \int_gzero_new:N \c@jCol
+%    \end{macrocode}
+% 
+% \bigskip
+% We recall that |\l_@@_last_row_int| and |\l_@@_last_column_int| are \emph{not}
+% the numbers of the last row and last column of the array. There are only the
+% values of the keys |last-row| and |last-column| (maybe the user has provided
+% erroneous values). The meaning of that counters does not change during the
+% environment of \pkg{nicematrix}. There is only a slight adjustment: if the
+% user have used one of those keys without value, we provide now the right value
+% as read on the |aux| file (of course, it's possible only after the first compilation).
+%    \begin{macrocode}
+    \int_compare:nNnT \l_@@_last_row_int = { -1 }
+      {
+        \bool_set_true:N \l_@@_last_row_without_value_bool
+        \bool_if:NT \g_@@_aux_found_bool
+          { \int_set:Nn \l_@@_last_row_int { \seq_item:Nn \c_@@_size_seq 3 } }   
+      }
+    \int_compare:nNnT \l_@@_last_col_int = { -1 }
+      {
+        \bool_if:NT \g_@@_aux_found_bool
+          { \int_set:Nn \l_@@_last_col_int { \seq_item:Nn \c_@@_size_seq 6 } }   
+      }
+%    \end{macrocode}
 %
+% \bigskip
+% If there is a exterior row, we patch a command used in |\@@_Cell:| in order to
+% keep track of some dimensions needed to the construction of that ``last row''.
 %    \begin{macrocode}
     \int_compare:nNnT \l_@@_last_row_int > { -2 }
       {
@@ -7747,58 +7798,36 @@ version 2005/12/01 or later.
               { \dim_max:nn \g_@@_dp_last_row_dim { \box_dp:N \l_@@_cell_box } }  
           }
       }
-    \int_compare:nNnT \l_@@_last_row_int = { -1 }
-      {
-        \bool_set_true:N \l_@@_last_row_without_value_bool
 %    \end{macrocode}
-% A value based on the name is more reliable than a value based on the number of
-% the environment.
+%
+% \bigskip
 %    \begin{macrocode}
-        \str_if_empty:NTF \l_@@_name_str
-          {
-            \cs_if_exist:cT { @@_last_row_ \int_use:N \g_@@_env_int } 
-              { 
-                \int_set:Nn \l_@@_last_row_int 
-                  { \use:c { @@_last_row_ \int_use:N \g_@@_env_int } }
-              }  
-          }
-          {
-            \cs_if_exist:cT { @@_last_row_ \l_@@_name_str } 
-              { 
-                \int_set:Nn \l_@@_last_row_int 
-                  { \use:c { @@_last_row_ \l_@@_name_str } }
-              }  
-          }
-      }
+    \seq_gclear:N \g_@@_submatrix_seq
 %    \end{macrocode}
-%
-% A value of $-1$ for the counter |\l_@@_last_col_int| means that the user has
-% used the option |last-col| without value, that is to say without specifying
-% the number of that last column. In this case, we try to read that value from
-% the |aux| file (if it has been written on a previous run).
+% 
+% \bigskip
+% Now the |\CodeBefore|.
+%   \begin{macrocode}
+    \bool_if:NT \l_@@_code_before_bool \@@_exec_code_before:
+%    \end{macrocode}
+% 
+% \bigskip
+% The value of |\g_@@_pos_of_blocks_seq| has been written on the |aux| file and
+% loaded before the (potential) execution of the |\CodeBefore|. Now, we clear
+% that variable because it will be reconstructed during the creation of the
+% array.
 %    \begin{macrocode}
-    \int_compare:nNnT \l_@@_last_col_int = { -1 }
-      {
-        \str_if_empty:NTF \l_@@_name_str
-          {
-            \cs_if_exist:cT { @@_last_col_ \int_use:N \g_@@_env_int } 
-              { 
-                \int_set:Nn \l_@@_last_col_int 
-                  { \use:c { @@_last_col_ \int_use:N \g_@@_env_int } }
-              }  
-          }
-          {
-            \cs_if_exist:cT { @@_last_col_ \l_@@_name_str } 
-              { 
-                \int_set:Nn \l_@@_last_col_int 
-                  { \use:c { @@_last_col_ \l_@@_name_str } }
-              }  
-          }
-      }
+    \seq_gclear:N \g_@@_pos_of_blocks_seq
 %    \end{macrocode}
+% Idem for other sequences written on the |aux| file.
+%    \begin{macrocode}
+    \seq_gclear_new:N \g_@@_multicolumn_cells_seq
+    \seq_gclear_new:N \g_@@_multicolumn_sizes_seq
+%    \end{macrocode}
+% 
 % 
 % \interitem
-% The code in |\@@_pre_array_ii:| is used only by |{NiceArrayWithDelims}|. 
+% The code in |\@@_pre_array_ii:| is used only here.
 %    \begin{macrocode}
     \@@_pre_array_ii:
 %    \end{macrocode}
@@ -7896,24 +7925,17 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 % First, we give values to the LaTeX counters |iRow| and |jCol|. We remind that,
 % in the |code-before| (and in the |\CodeAfter|) they represent the numbers of
-% rows and columns of the array (without the potential last row and last column).
+% rows and columns of the array (without the potential last row and last
+% column). The value of |\g_@@_row_total_int| is the number of the last row
+% (with potentially a last exterior row) and |\g_@@_col_total_int| is the number
+% of the last column (with potentially a last exterior column).
 %    \begin{macrocode}
-    \int_zero_new:N \c@iRow
-    \int_set:Nn \c@iRow
-      { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 2 }
-    \int_zero_new:N \c@jCol
-    \int_set:Nn \c@jCol
-      { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 4 }
-%    \end{macrocode}
-% We have to adjust the values of |\c@iRow| and |\c@jCol| to take into account
-% the potential last row and last column. A value of $-2$ for
-% |\l_@@_last_row_int| means that there is no last row. Idem for the columns.
-%    \begin{macrocode}
-    \int_compare:nNnF \l_@@_last_row_int = { -2 } 
-      { \int_decr:N \c@iRow } 
-    \int_compare:nNnF \l_@@_last_col_int = { -2 } 
-      { \int_decr:N \c@jCol } 
+    \int_set:Nn \c@iRow { \seq_item:Nn \c_@@_size_seq 2 }
+    \int_set:Nn \c@jCol { \seq_item:Nn \c_@@_size_seq 5 }
+    \int_set_eq:NN \g_@@_row_total_int { \seq_item:Nn \c_@@_size_seq 3 }
+    \int_set_eq:NN \g_@@_col_total_int { \seq_item:Nn \c_@@_size_seq 6 }
 %    \end{macrocode}
+% 
 %
 % Now, we will create all the |col| nodes and |row| nodes with the informations
 % written in the |aux| file. You use the technique described in the page~1229 of
@@ -7926,9 +7948,7 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 % First, the recreation of the |row| nodes.
 %    \begin{macrocode}
-    \int_step_inline:nnn 
-      { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 1 }
-      { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 2 + 1 }
+    \int_step_inline:nnn \l_@@_first_row_int { \g_@@_row_total_int + 1 }
       {
         \pgfsys@getposition { \@@_env: - row - ##1 } \@@_node_position:
         \pgfcoordinate { \@@_env: - row - ##1 }
@@ -7937,9 +7957,7 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 % Now, the recreation of the |col| nodes.
 %    \begin{macrocode}
-    \int_step_inline:nnn 
-      { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 3 }
-      { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 4 + 1 }
+    \int_step_inline:nnn \l_@@_first_col_int { \g_@@_col_total_int + 1 }
       {
         \pgfsys@getposition { \@@_env: - col - ##1 } \@@_node_position:
         \pgfcoordinate { \@@_env: - col - ##1 }
@@ -7952,8 +7970,9 @@ version 2005/12/01 or later.
     \@@_create_diag_nodes:
 %    \end{macrocode}
 %
-% \medskip
-% Now, the creation of the cell nodes |(i-j)|.
+% \medskip 
+% Now, the creation of the cell nodes |(i-j)|, and, maybe also the ``medium
+% nodes'' and the ``large nodes''.
 %    \begin{macrocode}
     \bool_if:NT \g_@@_recreate_cell_nodes_bool \@@_recreate_cell_nodes:
     \endpgfpicture
@@ -7977,18 +7996,6 @@ version 2005/12/01 or later.
     \cs_set_eq:NN \columncolor \@@_columncolor
     \cs_set_eq:NN \chessboardcolors \@@_chessboardcolors
     \cs_set_eq:NN \SubMatrix \@@_SubMatrix_in_code_before
-%    \end{macrocode}
-% The list of the cells which are in the (empty) corners is stored in the |aux|
-% file because we have to know it before the execution of the |\CodeBefore| (the
-% commands which color the cells, rows and columns won't color the cells which
-% are in the corners).
-%    \begin{macrocode}
-    \seq_if_exist:cT
-      { c_@@_corners_cells_ \int_use:N \g_@@_env_int _ seq }   
-      { 
-        \seq_set_eq:Nc \l_@@_corners_cells_seq
-          { c_@@_corners_cells_ \int_use:N \g_@@_env_int _ seq }
-      }
   }
 %    \end{macrocode}
 % 
@@ -8058,7 +8065,7 @@ version 2005/12/01 or later.
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_CodeBefore:w #1 \q_stop
   { 
-    \seq_if_exist:cT { @@_size_ \int_use:N \g_@@_env_int _ seq } 
+    \bool_if:NT \g_@@_aux_found_bool
       { 
         \@@_pre_code_before: 
         #1 
@@ -8074,17 +8081,16 @@ version 2005/12/01 or later.
 % nodes and |diag| nodes are available in that |\CodeBefore|. With the key
 % |create-cell-nodes|, the cell nodes, that is to say the nodes of the form
 % |(i-j)| (but not the extra nodes) are also available because those nodes also
-% are recreated and that recreation is done by the following command.
+% are recreated and that recreation is done by the following command. 
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_recreate_cell_nodes:
   {
-    \int_step_inline:nnn 
-      { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 1 }
-      { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 2 }
+    \int_step_inline:nnn \l_@@_first_row_int \g_@@_row_total_int
       {
-        \int_step_inline:nnn 
-          { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 3 }
-          { \seq_item:cn { @@_size_ \int_use:N \g_@@_env_int _ seq } 4 }
+        \pgfsys@getposition { \@@_env: - ##1 - base } \@@_node_position: 
+        \pgfcoordinate { \@@_env: - row - ##1 - base }
+          { \pgfpointdiff \@@_picture_position: \@@_node_position: }
+        \int_step_inline:nnn \l_@@_first_col_int \g_@@_col_total_int
           {
             \cs_if_exist:cT
               { pgf @ sys @ pdf @ mark @ pos @ \@@_env: - ##1 - ####1 - NW }
@@ -8102,6 +8108,7 @@ version 2005/12/01 or later.
               }
           }
       }
+    \@@_create_extra_nodes:
   }
 %    \end{macrocode}
 %
@@ -8116,6 +8123,7 @@ version 2005/12/01 or later.
     \@@_provide_pgfsyspdfmark:
     \bool_if:NT \c_@@_footnote_bool \savenotes 
 %    \end{macrocode}
+% 
 % The aim of the following |\bgroup| (the corresponding |\egroup| is, of course,
 % at the end of the environment) is to be able to put an exposant to a matrix in
 % a mathematical formula.
@@ -8198,14 +8206,31 @@ version 2005/12/01 or later.
 %    \begin{macrocode}
     \seq_gclear:N \g_@@_pos_of_stroken_blocks_seq
     \seq_gclear:N \g_@@_pos_of_xdots_seq
+    \tl_gclear_new:N \g_@@_code_before_tl 
+%    \end{macrocode}
+%
+% \bigskip
+% We load all the informations written in the |aux| file during previous
+% compilations corresponding to the current environment.
+%    \begin{macrocode}
+    \bool_gset_false:N \g_@@_aux_found_bool
+    \tl_if_exist:cT { c_@@ _ \int_use:N \g_@@_env_int _ tl }
+      { 
+        \bool_gset_true:N \g_@@_aux_found_bool
+        \use:c { c_@@ _ \int_use:N \g_@@_env_int _ tl } 
+      }
+%    \end{macrocode}
+% Now, we prepare the token list for the instructions that we will have to write
+% on the |aux| file at the end of the environment.
+%    \begin{macrocode}
+     \tl_gclear:N \g_@@_aux_tl
 %    \end{macrocode}
 % 
 %    \begin{macrocode}
-    \tl_if_exist:cT { g_@@_code_before_ \int_use:N \g_@@_env_int _ tl }
+    \tl_if_empty:NF \g_@@_code_before_tl 
       { 
         \bool_set_true:N \l_@@_code_before_bool
-        \exp_args:NNv \tl_put_right:Nn \l_@@_code_before_tl 
-          { g_@@_code_before_ \int_use:N \g_@@_env_int _ tl }
+        \tl_put_right:NV \l_@@_code_before_tl \g_@@_code_before_tl 
       }
 %    \end{macrocode}
 % 
@@ -8431,6 +8456,23 @@ version 2005/12/01 or later.
 % a mathematical formula.
 %    \begin{macrocode}
     \egroup 
+%    \end{macrocode}
+% 
+% \bigskip
+% We want to write on the |aux| file all the informations corresponding to the
+% current environment.
+%    \begin{macrocode}
+    \iow_now:Nn \@mainaux { \ExplSyntaxOn }
+    \iow_now:Nx \@mainaux 
+      {
+        \tl_gset:cn { c_@@_ \int_use:N \g_@@_env_int _ tl } 
+          \iow_newline: { \iow_newline: \exp_not:V \g_@@_aux_tl } 
+      }
+    \iow_now:Nn \@mainaux { \ExplSyntaxOff }
+%    \end{macrocode}
+%
+% \bigskip
+%    \begin{macrocode}
     \bool_if:NT \c_@@_footnote_bool \endsavenotes 
   }
 %    \end{macrocode}
@@ -8490,7 +8532,7 @@ version 2005/12/01 or later.
         \@tempswatrue
 %    \end{macrocode}
 % The following line actually does the expansion (it's has been copied from
-% |array.sty|). 
+% |array.sty|). The expanded version is still in |\@temptokena|.
 %    \begin{macrocode}
         \@whilesw \if@tempswa \fi { \@tempswafalse \the \NC@list }
 %    \end{macrocode}
@@ -8505,7 +8547,7 @@ version 2005/12/01 or later.
 % |\@@_patch_preamble:n|. In the same time, we will count the columns with the
 % counter |\c@jCol|.
 %    \begin{macrocode}
-        \int_gzero_new:N \c@jCol
+        \int_gzero:N \c@jCol
         \tl_gclear:N \g_@@_preamble_tl 
         \tl_if_eq:NnTF \l_@@_vlines_clist { all } 
           { 
@@ -9892,102 +9934,58 @@ version 2005/12/01 or later.
 %
 % If we are in an environment without preamble (like |{NiceMatrix}| or
 % |{pNiceMatrix}|) and if the option |last-col| has been used without value
-% we fix the real value of |\l_@@_last_col_int|.
+% we also fix the real value of |\l_@@_last_col_int|.
 %    \begin{macrocode}
     \bool_if:NT \l_@@_last_col_without_value_bool
-      {
-        \dim_set_eq:NN \l_@@_last_col_int \g_@@_col_total_int 
-        \iow_shipout:Nn \@mainaux \ExplSyntaxOn 
-        \iow_shipout:Nx \@mainaux 
-          { 
-            \cs_gset:cpn { @@_last_col_ \int_use:N \g_@@_env_int } 
-              { \int_use:N \g_@@_col_total_int }
-          }   
-        \str_if_empty:NF \l_@@_name_str
-          { 
-            \iow_shipout:Nx \@mainaux 
-              { 
-                \cs_gset:cpn { @@_last_col_ \l_@@_name_str } 
-                  { \int_use:N \g_@@_col_total_int }
-              }  
-          }
-        \iow_shipout:Nn \@mainaux \ExplSyntaxOff 
-      }
+      { \int_set_eq:NN \l_@@_last_col_int \g_@@_col_total_int }
 %    \end{macrocode}
 % 
-% It's also time to give to |\l_@@_last_row_int| its real value. But, if the
-% user had used the option |last-row| without value, we write in the |aux| file
-% the number of that last row for the next run.
+% \medskip
+% It's also time to give to |\l_@@_last_row_int| its real value. 
 %    \begin{macrocode}
     \bool_if:NT \l_@@_last_row_without_value_bool
-      {
-        \dim_set_eq:NN \l_@@_last_row_int \g_@@_row_total_int
-%    \end{macrocode}
-% If the option |light-syntax| is used, we have nothing to write since, in this
-% case, the number of rows is directly determined.
-%    \begin{macrocode}
-        \bool_if:NF \l_@@_light_syntax_bool
-          {
-            \iow_shipout:Nn \@mainaux \ExplSyntaxOn 
-            \iow_shipout:Nx \@mainaux 
-              { 
-                \cs_gset:cpn { @@_last_row_ \int_use:N \g_@@_env_int } 
-                  { \int_use:N \g_@@_row_total_int }
-              }   
+      { \int_set_eq:NN \l_@@_last_row_int \g_@@_row_total_int }
 %    \end{macrocode}
-% If the environment has a name, we also write a value based on the name
-% because it's more reliable than a value based on the number of the
-% environment. 
+% 
+% \medskip
 %    \begin{macrocode}
-            \str_if_empty:NF \l_@@_name_str
-              { 
-                \iow_shipout:Nx \@mainaux 
-                  { 
-                    \cs_gset:cpn { @@_last_row_ \l_@@_name_str } 
-                      { \int_use:N \g_@@_row_total_int }
-                  }  
-              }
-            \iow_shipout:Nn \@mainaux \ExplSyntaxOff 
+    \tl_gput_right:Nx \g_@@_aux_tl
+      { 
+        \seq_gset_from_clist:Nn \exp_not:N \c_@@_size_seq 
+          { 
+            \int_use:N \l_@@_first_row_int ,
+            \int_use:N \c@iRow , 
+            \int_use:N \g_@@_row_total_int ,
+            \int_use:N \l_@@_first_col_int ,
+            \int_use:N \c@jCol ,
+            \int_use:N \g_@@_col_total_int 
           }
+        \iow_newline:
       }
 %    \end{macrocode}
-% 
-% If the key |code-before| is used, we have to write on the |aux| file the actual
-% size of the array and other informations.
-%    \begin{macrocode}
-    \bool_if:NT \l_@@_code_before_bool
-      {
-        \iow_now:Nn \@mainaux \ExplSyntaxOn
-        \iow_now:Nx \@mainaux
-          { \seq_clear_new:c { @@_size _ \int_use:N \g_@@_env_int _ seq } }
-        \iow_now:Nx \@mainaux
-          {
-            \seq_gset_from_clist:cn { @@_size _ \int_use:N \g_@@_env_int _ seq }
-              { 
-                \int_use:N \l_@@_first_row_int , 
-                \int_use:N \g_@@_row_total_int ,
-                \int_use:N \l_@@_first_col_int ,
-%    \end{macrocode}
-% If the user has used a key |last-row| in an environment with preamble (like
-% |{pNiceArray}|) and that that last row has not been found, we have to
-% increment the value because it will be decreased when used in the |code-before|.
-%    \begin{macrocode}
-                \bool_lazy_and:nnTF
-                  { \int_compare_p:nNn \l_@@_last_col_int > { -2 } }
-                  { \bool_not_p:n \g_@@_last_col_found_bool }
-                  \@@_succ:n 
-                  \int_use:N 
-                \g_@@_col_total_int 
-              }
-%    \end{macrocode}
 % We write also the potential content of |\g_@@_pos_of_blocks_seq| (it will be
 % useful if the command |\rowcolors| is used with the key |respect-blocks|).
 %    \begin{macrocode}
-            \seq_gset_from_clist:cn
-              { c_@@_pos_of_blocks_ \int_use:N \g_@@_env_int _ seq }
+    \seq_if_empty:NF \g_@@_pos_of_blocks_seq
+      {
+        \tl_gput_right:Nx \g_@@_aux_tl
+          { 
+            \seq_gset_from_clist:Nn \exp_not:N \g_@@_pos_of_blocks_seq
               { \seq_use:Nnnn \g_@@_pos_of_blocks_seq , , , }
+            \iow_newline:
+          }
+      }
+    \seq_if_empty:NF \g_@@_multicolumn_cells_seq
+      {
+        \tl_gput_right:Nx \g_@@_aux_tl
+          { 
+            \seq_gset_from_clist:Nn \exp_not:N \g_@@_multicolumn_cells_seq
+              { \seq_use:Nnnn \g_@@_multicolumn_cells_seq , , , }
+            \iow_newline:
+            \seq_gset_from_clist:Nn \exp_not:N \g_@@_multicolumn_sizes_seq
+              { \seq_use:Nnnn \g_@@_multicolumn_sizes_seq , , , }
+            \iow_newline:
           }
-        \iow_now:Nn \@mainaux \ExplSyntaxOff
       }
 %    \end{macrocode}
 %
@@ -10166,14 +10164,12 @@ version 2005/12/01 or later.
 %    \begin{macrocode}
         \cs_set_protected:Npn \rectanglecolor { }
         \cs_set_protected:Npn \columncolor { }
-        \iow_now:Nn \@mainaux \ExplSyntaxOn
-        \iow_now:Nx \@mainaux
+        \tl_gput_right:Nx \g_@@_aux_tl
           {
-            \tl_gset:cn 
-              { g_@@_code_before_ \int_use:N \g_@@_env_int _ tl }
+            \tl_gset:Nn \exp_not:N \g_@@_code_before_tl 
               { \exp_not:V \g_nicematrix_code_before_tl }
+            \iow_newline:
           }
-        \iow_now:Nn \@mainaux \ExplSyntaxOff
         \bool_set_true:N \l_@@_code_before_bool
       }
 %    \end{macrocode}
@@ -12400,19 +12396,14 @@ version 2005/12/01 or later.
 % color or of the second color.
 %    \begin{macrocode}
     \bool_set_true:N \l_tmpa_bool
-    \bool_lazy_and:nnT
-      \l_@@_respect_blocks_bool
-      { 
-        \cs_if_exist_p:c 
-         { c_@@_pos_of_blocks_ \int_use:N \g_@@_env_int _ seq } }  
+    \bool_if:NT \l_@@_respect_blocks_bool
       {
 %    \end{macrocode}
 % We don't want to take into account a block which is completely in the ``first
 % column'' of (number $0$) or in the ``last column'' and that's why we filter
 % the sequence of the blocks (in a the sequence |\l_tmpa_seq|).
 %    \begin{macrocode}
-        \seq_set_eq:Nc \l_tmpb_seq 
-          { c_@@_pos_of_blocks_ \int_use:N \g_@@_env_int _ seq } 
+        \seq_set_eq:NN \l_tmpb_seq \g_@@_pos_of_blocks_seq 
         \seq_set_filter:NNn \l_tmpa_seq \l_tmpb_seq
           { \@@_not_in_exterior_p:nnnn ##1 }
       }
@@ -12443,12 +12434,7 @@ version 2005/12/01 or later.
 % If the key |respect-blocks| is in force, we have to adjust that value (of
 % course). 
 %    \begin{macrocode}
-            \bool_lazy_and:nnT
-              \l_@@_respect_blocks_bool
-              { 
-                \cs_if_exist_p:c 
-                  { c_@@_pos_of_blocks_ \int_use:N \g_@@_env_int _ seq } 
-              } 
+            \bool_if:NT \l_@@_respect_blocks_bool
               {
                 \seq_set_filter:NNn \l_tmpb_seq \l_tmpa_seq 
                   { \@@_intersect_our_row_p:nnnn ####1 }
@@ -13299,14 +13285,12 @@ version 2005/12/01 or later.
 % commands which color the |rows|, |columns| and |cells| must not color the
 % cells in the corners.
 %    \begin{macrocode}
-        \iow_now:Nn \@mainaux \ExplSyntaxOn
-        \iow_now:Nx \@mainaux
+        \tl_gput_right:Nx \g_@@_aux_tl
           {
-            \seq_gset_from_clist:cn
-              { c_@@_corners_cells_ \int_use:N \g_@@_env_int _ seq }
+            \seq_set_from_clist:Nn \exp_not:N \l_@@_corners_cells_seq 
               { \seq_use:Nnnn \l_@@_corners_cells_seq , , , }
+            \iow_newline:
           }
-        \iow_now:Nn \@mainaux \ExplSyntaxOff
       }
   }
 %    \end{macrocode}
@@ -17481,6 +17465,12 @@ version 2005/12/01 or later.
 % The version 5.15b is compatible with the version 3.0+ of \pkg{siunitx}
 % (previous versions were not).
 %
+% % \subsection*{Changes between versions 5.15 and 5.16}
+%
+% It's now possible to use the cells corresponding to the contents of the nodes
+% (of the form |i-j|) in the |\CodeBefore| when the key |create-cell-nodes| of
+% that |\CodeBefore| is used. The medium and the large nodes are also available
+% if the corresponding keys are used.
 %
 % \PrintIndex
 % 
diff --git a/macros/latex/contrib/nicematrix/nicematrix.pdf b/macros/latex/contrib/nicematrix/nicematrix.pdf
index b096ea1e0f..40b867d72e 100644
--- a/macros/latex/contrib/nicematrix/nicematrix.pdf
+++ b/macros/latex/contrib/nicematrix/nicematrix.pdf