nicematrix (27may19)

git-svn-id: svn://tug.org/texlive/trunk@51234 c570f23f-e606-0410-a88d-b1316a301751

4 files changed, 3752 insertions, 2776 deletions

diff --git a/Master/texmf-dist/doc/latex/nicematrix/README.md b/Master/texmf-dist/doc/latex/nicematrix/README.md
index 39cc99c2853..aadca62b15f 100644
--- a/Master/texmf-dist/doc/latex/nicematrix/README.md
+++ b/Master/texmf-dist/doc/latex/nicematrix/README.md
@@ -1,10 +1,13 @@
 # Readme for the package nicematrix
 
+Author : F. Pantigny (`fpantigny@wanadoo.fr`).
+
+CTAN page : `https://ctan.org/pkg/nicematrix`
+
 ## License
 The LaTeX extension `nicematrix` is distributed under the LPPL 1.3 license.
 
 ## Presentation
-This extension has been written by F. Pantigny (`fpantigny@wanadoo.fr`).
 
 The LaTeX package `nicematrix` provides new environments similar to the classical environments
 `{array}` and `{matrix}` but with some additional features. Among these features are the
diff --git a/Master/texmf-dist/doc/latex/nicematrix/nicematrix.pdf b/Master/texmf-dist/doc/latex/nicematrix/nicematrix.pdf
index 5d6e1f65e26..908368d1d6e 100644
--- a/Master/texmf-dist/doc/latex/nicematrix/nicematrix.pdf
+++ b/Master/texmf-dist/doc/latex/nicematrix/nicematrix.pdf
diff --git a/Master/texmf-dist/source/latex/nicematrix/nicematrix.dtx b/Master/texmf-dist/source/latex/nicematrix/nicematrix.dtx
index f21c03b01e8..618964b20c9 100644
--- a/Master/texmf-dist/source/latex/nicematrix/nicematrix.dtx
+++ b/Master/texmf-dist/source/latex/nicematrix/nicematrix.dtx
@@ -15,8 +15,8 @@
 %
 % \fi
 % \iffalse
-\def\myfileversion{2.1.4}
-\def\myfiledate{2019/01/28}
+\def\myfileversion{2.1.5}
+\def\myfiledate{2019/05/27}
 %
 %
 %<*batchfile>
@@ -44,7 +44,7 @@ version 2005/12/01 or later.
 \endgroup
 %</batchfile>
 %
-%<@@=nicem>
+%<@@=nm>
 %<*driver>
 \documentclass[dvipsnames]{l3doc}% dvipsnames is for xcolor (loaded by Tikz, loaded by nicematrix)
 \VerbatimFootnotes
@@ -80,8 +80,9 @@ version 2005/12/01 or later.
 % \maketitle
 %
 % \begin{abstract}
-% The LaTeX package \pkg{nicematrix} provides new environments similar to the classical environments |{array}| and
-% |{matrix}| but with some additional features. Among these features are the possibilities to fix the width of the
+% The LaTeX package \pkg{nicematrix} provides new environments similar to the
+% classical environments |{array}| and |{matrix}| but with some additional
+% features. Among these features are the possibilities to fix the width of the
 % columns and to draw continuous ellipsis dots between the cells of the array.
 % \end{abstract}
 %
@@ -89,20 +90,22 @@ version 2005/12/01 or later.
 % \section{Presentation}
 %
 %
-% This package can be used with |xelatex|, |lualatex|, |pdflatex| but also by the classical workflow
-% |latex|-|dvips|-|ps2pdf| (or Adobe Distiller). Two or three compilations may be necessary. This package requires
-% and loads the packages \pkg{expl3}, \pkg{l3keys2e}, \pkg{xparse}, \pkg{array}, \pkg{amsmath} and \pkg{tikz}. It
-% also loads the Tikz library \pkg{fit}.
+% This package can be used with |xelatex|, |lualatex|, |pdflatex| but also by
+% the classical workflow |latex|-|dvips|-|ps2pdf| (or Adobe Distiller). Two or
+% three compilations may be necessary. This package requires and loads the
+% packages \pkg{expl3}, \pkg{l3keys2e}, \pkg{xparse}, \pkg{array}, \pkg{amsmath}
+% and \pkg{tikz}. It also loads the Tikz library \pkg{fit}.
 %
 %
 %
 % \medskip
 % \begin{savenotes}
 % \begin{minipage}{0.6\linewidth}
-% This package provides some new tools to draw mathematical matrices. The main features are the following:
+% This package provides some new tools to draw mathematical matrices. The main
+% features are the following:
 % 
-% \textbullet\ continuous dotted lines\footnote{If the class option |draft| is used, these dotted lines will not be
-% drawn for a faster compilation.};
+% \textbullet\ continuous dotted lines\footnote{If the class option |draft| is
+% used, these dotted lines will not be drawn for a faster compilation.};
 %
 % \textbullet\ a first row and a last column for labels;
 %
@@ -123,8 +126,8 @@ version 2005/12/01 or later.
 % }$
 % 
 % \medskip
-% A command |\NiceMatrixOptions| is provided to fix the options (the scope of the options fixed by this command is
-% the current TeX group).
+% A command |\NiceMatrixOptions| is provided to fix the options (the scope of
+% the options fixed by this command is the current TeX group).
 %
 % 
 % \bigskip
@@ -132,7 +135,8 @@ version 2005/12/01 or later.
 %
 % \medskip
 % \begin{minipage}{10cm}
-% For example, consider the following code which uses an environment |{pmatrix}| of \pkg{amsmath}.
+% For example, consider the following code which uses an environment |{pmatrix}|
+% of \pkg{amsmath}.
 %
 % \smallskip
 % \begin{BVerbatim}
@@ -159,8 +163,8 @@ version 2005/12/01 or later.
 % \begin{scope}
 % \NiceMatrixOptions{transparent}
 % \begin{minipage}{10cm}
-% Now, if we use the package \pkg{nicematrix} with the option |transparent|, the same code will give the 
-% result on the right.
+% Now, if we use the package \pkg{nicematrix} with the option |transparent|, the
+% same code will give the result on the right.
 % \end{minipage}\hspace{1cm}
 % $A = \begin{pmatrix}
 % 1      & \cdots & \cdots & 1      \\
@@ -190,45 +194,55 @@ version 2005/12/01 or later.
 %
 %
 % \medskip
-% By default, the environments |{NiceMatrix}|, |{pNiceMatrix}|, |{bNiceMatrix}|, |{BNiceMatrix}|, |{vNiceMatrix}|
-% and |{VNiceMatrix}| behave almost exactly as the corresponding environments of \pkg{amsmath}:
-% |{matrix}|, |{pmatrix}|, |{bmatrix}|, |{Bmatrix}|, |{vmatrix}| and |{Vmatrix}|.
+% By default, the environments |{NiceMatrix}|, |{pNiceMatrix}|, |{bNiceMatrix}|,
+% |{BNiceMatrix}|, |{vNiceMatrix}| and |{VNiceMatrix}| behave almost exactly as
+% the corresponding environments of \pkg{amsmath}: |{matrix}|, |{pmatrix}|,
+% |{bmatrix}|, |{Bmatrix}|, |{vmatrix}| and |{Vmatrix}|.
 % 
 %
 % \medskip
-% The environment |{NiceArray}| is similar to the environment |{array}| of the package |{array}|. However, for
-% technical reasons, in the preamble of the environment |{NiceArray}|, the user must use the letters |L|, |C|
-% and~|R| instead of |l|, |c| and |r|. It's possible to use the constructions \verb|w{...}{...}|,
-% \verb|W{...}{...}|, \verb+|+, |>{...}|, |<{...}|, |@{...}|, |!{...}| and |*{n}{...}| but the letters |p|, |m| and
-% |b| should not be used. See p.~\pageref{NiceArray} the section relating to |{NiceArray}|.
+% The environment |{NiceArray}| is similar to the environment |{array}| of the
+% package |{array}|. However, for technical reasons, in the preamble of the
+% environment |{NiceArray}|, the user must use the letters |L|, |C| and~|R|
+% instead of |l|, |c| and |r|. It's possible to use the constructions
+% \verb|w{...}{...}|, \verb|W{...}{...}|, \verb+|+, |>{...}|, |<{...}|,
+% |@{...}|, |!{...}| and |*{n}{...}| but the letters |p|, |m| and |b| should not
+% be used. See p.~\pageref{NiceArray} the section relating to |{NiceArray}|.
 %
 % \medskip
-% The environments with |C| at the end of their name, |{pNiceArrayC}|, |{bNiceArrayC}|, |{BNiceArrayC}|,
-% |{vNiceArrayC}| and |{VNiceArrayC}| are similar to the environment |{NiceArray}| (especially the special letters
-% |L|, |C| and |R|) but create an exterior column (on the right of the closing delimiter). See
-% p.~\pageref{pNiceArrayC} the section relating to |{pNiceArrayC}|. 
+% The environments with |C| at the end of their name, |{pNiceArrayC}|,
+% |{bNiceArrayC}|, |{BNiceArrayC}|, |{vNiceArrayC}| and |{VNiceArrayC}| are
+% similar to the environment |{NiceArray}| (especially the special letters |L|,
+% |C| and |R|) but create an exterior column (on the right of the closing
+% delimiter). See p.~\pageref{pNiceArrayC} the section relating to
+% |{pNiceArrayC}|.
 %
 % \medskip 
-% The environments with |RC|, |{pNiceArrayRC}|, |{bNiceArrayRC}|, |{BNiceArrayRC}|, |{vNiceArrayRC}|,
-% |{VNiceArrayRC}| are similar to the environment |{NiceArray}| but create an exterior row (above the main matrix)
-% and an exterior column. See p.~\pageref{pNiceArrayRC} the section relating to |{pNiceArrayRC}|.
+% The environments with |RC|, |{pNiceArrayRC}|, |{bNiceArrayRC}|,
+% |{BNiceArrayRC}|, |{vNiceArrayRC}|, |{VNiceArrayRC}| are similar to the
+% environment |{NiceArray}| but create an exterior row (above the main matrix)
+% and an exterior column. See p.~\pageref{pNiceArrayRC} the section relating to
+% |{pNiceArrayRC}|.
 %
 % 
 % 
 % \section{The continuous dotted lines}
 %
-% Inside the environments of the extension \pkg{nicematrix}, new commands are defined: |\Ldots|, |\Cdots|,
-% |\Vdots|, |\Ddots|, and |\Iddots|. These commands are intended to be used in place of |\dots|, |\cdots|,
-% |\vdots|, |\ddots| and |\iddots|.\footnote{The command |\iddots|, defined in \pkg{nicematrix}, is a variant of
-% |\ddots| with dots going forward: \smash{$\iddots$}. If |mathdots| is loaded, the version of |mathdots| is used.
-% It corresponds to the command |\adots| of \pkg{unicode-math}.}
+% Inside the environments of the extension \pkg{nicematrix}, new commands are
+% defined: |\Ldots|, |\Cdots|, |\Vdots|, |\Ddots|, and |\Iddots|. These commands
+% are intended to be used in place of |\dots|, |\cdots|, |\vdots|, |\ddots| and
+% |\iddots|.\footnote{The command |\iddots|, defined in \pkg{nicematrix}, is a
+% variant of |\ddots| with dots going forward: \smash{$\iddots$}. If |mathdots|
+% is loaded, the version of |mathdots| is used. It corresponds to the command
+% |\adots| of \pkg{unicode-math}.}
 %
 % \smallskip
-% Each of them must be used alone in the cell of the array and it draws a dotted line between the first non-empty
-% cells\footnote{The precise definition of a ``non-empty cell'' is given below (cf. p.~\pageref{empty-cells}).} on
-% both sides of the current cell. Of course, for |\Ldots| and |\Cdots|, it's an horizontal line; for |\Vdots|, it's
-% a vertical line and for |\Ddots| and |\Iddots| diagonal ones.\par\nobreak
-% \bigskip
+% Each of them must be used alone in the cell of the array and it draws a dotted
+% line between the first non-empty cells\footnote{The precise definition of a
+% ``non-empty cell'' is given below (cf. p.~\pageref{empty-cells}).} on both
+% sides of the current cell. Of course, for |\Ldots| and |\Cdots|, it's an
+% horizontal line; for |\Vdots|, it's a vertical line and for |\Ddots| and
+% |\Iddots| diagonal ones.\par\nobreak \bigskip
 % \begin{BVerbatim}[baseline=c,boxwidth=10cm]
 % \begin{bNiceMatrix}
 % a_1      & \Cdots &        & & a_1 \\
@@ -247,8 +261,8 @@ version 2005/12/01 or later.
 % \end{bNiceMatrix}$
 % 
 % \interitem
-% In order to represent the null matrix, one can use the following codage:\par\nobreak
-% \bigskip
+% In order to represent the null matrix, one can use the following
+% codage:\par\nobreak \bigskip
 % \begin{BVerbatim}[baseline=c,boxwidth=10cm]
 % \begin{bNiceMatrix}
 % 0      & \Cdots & 0      \\
@@ -263,9 +277,9 @@ version 2005/12/01 or later.
 % \end{bNiceMatrix}$
 %
 % \bigskip
-% However, one may want a larger matrix. Usually, in such a case, the users of LaTeX add a new row and a new
-% column. It's possible to use the same method with \pkg{nicematrix}:\par\nobreak
-% \bigskip
+% However, one may want a larger matrix. Usually, in such a case, the users of
+% LaTeX add a new row and a new column. It's possible to use the same method
+% with \pkg{nicematrix}:\par\nobreak \bigskip
 % \begin{BVerbatim}[baseline=c,boxwidth=10cm]
 % \begin{bNiceMatrix}
 % 0      & \Cdots & \Cdots & 0      \\
@@ -282,15 +296,19 @@ version 2005/12/01 or later.
 % \end{bNiceMatrix}$
 % 
 % \bigskip
-% In the first column of this exemple, there are two instructions |\Vdots| but only one dotted line is drawn (there
-% is no overlapping graphic objects in the resulting \textsc{pdf}\footnote{And it's not possible to draw a |\Ldots|
-% and a |\Cdots| line between the same cells.}).
-%
-% However, useless computations are performed by TeX before detecting that both instructions would eventually yield
-% the same dotted line. That's why the package \pkg{nicematrix} provides starred versions of |\Ldots|, |\Cdots|,
-% etc.: |\Ldots*|, |\Cdots*|, etc. These versions are simply equivalent to |\hphantom{\ldots}|,
-% |\hphantom{\cdots}|, etc. The user should use these starred versions whenever a classical version has already
-% been used for the same dotted line.\par\nobreak
+% In the first column of this exemple, there are two instructions |\Vdots| but
+% only one dotted line is drawn (there is no overlapping graphic objects in the
+% resulting \textsc{pdf}\footnote{And it's not possible to draw a |\Ldots| and a
+% |\Cdots| line between the same cells.}).
+%
+% However, useless computations are performed by TeX before detecting that both
+% instructions would eventually yield the same dotted line. That's why the
+% package \pkg{nicematrix} provides starred versions of |\Ldots|, |\Cdots|,
+% etc.: |\Ldots*|, |\Cdots*|, etc. These versions are simply equivalent to
+% |\hphantom{\ldots}|, |\hphantom{\cdots}|, etc. The user should use these
+% starred versions whenever a classical version has already been used for the
+% same dotted line.\par\nobreak 
+%
 % \bigskip
 % \begin{BVerbatim}[baseline=c,boxwidth=10cm]
 % \begin{bNiceMatrix}
@@ -308,8 +326,8 @@ version 2005/12/01 or later.
 % \end{bNiceMatrix}$
 %
 % \bigskip
-% In fact, in this example, it would be possible to draw the same matrix without starred commands with the
-% following code:\par\nobreak
+% In fact, in this example, it would be possible to draw the same matrix without
+% starred commands with the following code:\par\nobreak
 % \bigskip
 % \begin{BVerbatim}[baseline=c,boxwidth=10cm]
 % \begin{bNiceMatrix}
@@ -327,14 +345,16 @@ version 2005/12/01 or later.
 % \end{bNiceMatrix}$
 %
 % \bigskip
-% There are also other means to change the size of the matrix. Someone might want to use the optional argument of
-% the command~|\\| for the vertical dimension and a command~|\hspace*| in a cell for the horizontal
-% dimension.\footnote{Nevertheless, the best way to fix the width of a column is to use the environment
-% |{NiceArray}| with a column of type~|w| (or |W|).}
-% 
-% However, a command~|\hspace*| might interfer with the construction of the dotted lines. That's why the package
-% \pkg{nicematrix} provides a command~|\Hspace| which is a variant of |\hspace| transparent for the dotted lines of
-% \pkg{nicematrix}.\par\nobreak
+% There are also other means to change the size of the matrix. Someone might
+% want to use the optional argument of the command~|\\| for the vertical
+% dimension and a command~|\hspace*| in a cell for the horizontal
+% dimension.\footnote{Nevertheless, the best way to fix the width of a column is
+% to use the environment |{NiceArray}| with a column of type~|w| (or |W|).}
+% 
+% However, a command~|\hspace*| might interfer with the construction of the
+% dotted lines. That's why the package \pkg{nicematrix} provides a
+% command~|\Hspace| which is a variant of |\hspace| transparent for the dotted
+% lines of \pkg{nicematrix}.\par\nobreak
 % \bigskip
 % \begin{BVerbatim}[baseline=c,boxwidth=10cm]
 % \begin{bNiceMatrix}
@@ -351,7 +371,9 @@ version 2005/12/01 or later.
 % 
 % \subsection{The option nullify-dots}
 %
-% Consider the following matrix composed classicaly with the environment |{pmatrix}|.\par\nobreak
+% Consider the following matrix composed classicaly with the environment
+% |{pmatrix}|.\par\nobreak 
+% 
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=8cm]
 % $A = \begin{pmatrix}
@@ -374,7 +396,8 @@ version 2005/12/01 or later.
 %
 %
 % \bigskip
-% If we add |\vdots| instructions in the second column, the geometry of the matrix is modified.\par\nobreak
+% If we add |\vdots| instructions in the second column, the geometry of the
+% matrix is modified.\par\nobreak
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=8cm]
 % $B = \begin{pmatrix}
@@ -396,8 +419,9 @@ version 2005/12/01 or later.
 % \end{pmatrix}$
 %
 % \bigskip
-% By default, with \pkg{nicematrix}, if we replace |{pmatrix}| by |{pNiceMatrix}| and |\vdots| by
-% |\Vdots| (or |\Vdots*| for efficiency), the geometry of the matrix is not changed.\par\nobreak
+% By default, with \pkg{nicematrix}, if we replace |{pmatrix}| by
+% |{pNiceMatrix}| and |\vdots| by |\Vdots| (or |\Vdots*| for efficiency), the
+% geometry of the matrix is not changed.\par\nobreak
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=8cm]
 % $C = \begin{pNiceMatrix}
@@ -419,9 +443,10 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}$
 %
 % \bigskip
-% However, one may prefer the geometry of the first matrix $A$ and would like to have such a geometry with a dotted
-% line in the second column. It's possible by using the option |nullify-dots| (and only one instruction |\Vdots| is
-% necessary).\par\nobreak
+% However, one may prefer the geometry of the first matrix $A$ and would like to
+% have such a geometry with a dotted line in the second column. It's possible by
+% using the option |nullify-dots| (and only one instruction |\Vdots| is
+% necessary).\par\nobreak 
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=8cm]
 % $D = \begin{pNiceMatrix}[~emphase#nullify-dots@]
@@ -443,19 +468,23 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}$
 %
 % \medskip
-% The option |nullify-dots| smashes the instructions |\Ldots| (and the variants) vertically but also horizontally.
+% The option |nullify-dots| smashes the instructions |\Ldots| (and the variants)
+% vertically but also horizontally.
 %
 % \medskip
-% \textbf{There must be no space before the opening bracket (|[|) of the options of the environment.}
+% \textbf{There must be no space before the opening bracket (|[|) of the options
+% of the environment.}
 %
 % \subsection{The command Hdotsfor}
 %
-% Some people commonly use the command |\hdotsfor| of \pkg{amsmath} in order to draw horizontal dotted lines in a
-% matrix. In the environments of \pkg{nicematrix}, one should use instead |\Hdotsfor| in order to draw dotted lines similar
-% to the other dotted lines drawn by the package \pkg{nicematrix}.
+% Some people commonly use the command |\hdotsfor| of \pkg{amsmath} in order to
+% draw horizontal dotted lines in a matrix. In the environments of
+% \pkg{nicematrix}, one should use instead |\Hdotsfor| in order to draw dotted
+% lines similar to the other dotted lines drawn by the package \pkg{nicematrix}.
 %
-% As with the other commands of \pkg{nicematrix} (like |\Cdots|, |\Ldots|, |\Vdots|, etc.), the dotted line drawn
-% with |\Hdotsfor| extends until the contents of the cells on both sides.
+% As with the other commands of \pkg{nicematrix} (like |\Cdots|, |\Ldots|,
+% |\Vdots|, etc.), the dotted line drawn with |\Hdotsfor| extends until the
+% contents of the cells on both sides.
 %
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=7cm]
@@ -474,8 +503,8 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}$
 %
 % \bigskip
-% However, if these cells are empty, the dotted line extends only in the cells specified by the argument of
-% |\Hdotsfor| (by design).
+% However, if these cells are empty, the dotted line extends only in the cells
+% specified by the argument of |\Hdotsfor| (by design).
 %
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=7cm]
@@ -494,39 +523,44 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}$
 %
 % \bigskip
-% The command |\hdotsfor| of \pkg{amsmath} takes an optional argument (between square brackets) which is 
-% used for fine tuning of the space beetween two consecutive dots. For homogeneity, |\Hdotsfor| has
-% also an optional argument but this argument is discarded silently.
+% The command |\hdotsfor| of \pkg{amsmath} takes an optional argument (between
+% square brackets) which is used for fine tuning of the space beetween two
+% consecutive dots. For homogeneity, |\Hdotsfor| has also an optional argument
+% but this argument is discarded silently.
 %
-% Remark: Unlike the command |\hdotsfor| of \pkg{amsmath}, the command |\Hdotsfor| is compatible with the extension
-% \pkg{colortbl}.  
+% Remark: Unlike the command |\hdotsfor| of \pkg{amsmath}, the command
+% |\Hdotsfor| is compatible with the extension \pkg{colortbl}.
 % 
 % \subsection{How to generate the continuous dotted lines transparently}
 %
-% The package \pkg{nicematrix} provides an option called |transparent| for using existing code transparently in the
-% environments |{matrix}|. This option can be set as option of |\usepackage| or with the command
-% |\NiceMatrixOptions|.
+% The package \pkg{nicematrix} provides an option called |transparent| for using
+% existing code transparently in the environments |{matrix}|. This option can be
+% set as option of |\usepackage| or with the command |\NiceMatrixOptions|.
 % 
 %
-% In fact, this option is an alias for the conjonction of two options: |renew-dots| and |renew-matrix|.
+% In fact, this option is an alias for the conjonction of two options:
+% |renew-dots| and |renew-matrix|.
 %
 % \smallskip
 %
 % \begin{itemize}
 % \item The option |renew-dots|\par\nobreak
-% With this option, the commands |\ldots|, |\cdots|, |\vdots|, |\ddots|, |\iddots|\footnote{The command
-% |\iddots| is not a command of LaTeX but is defined by the package \pkg{nicematrix}. If |mathdots| is loaded, the
-% version of |mathdots| is used.} and |\hdotsfor| are redefined within the environments provided by \pkg{nicematrix} 
-% and behave like |\Ldots|, |\Cdots|, |\Vdots|, |\Ddots|, |\Iddots| and |\Hdotsfor|; the command |\dots| (``automatic
-% dots'' of |amsmath|) is also redefined to behave like |\Ldots|.
-%
-% \item  The option |renew-matrix|\par\nobreak
-% With this option, the environment |{matrix}| is redefined and behave like |{NiceMatrix}|, and so on for the five
-% variants.
+% With this option, the commands |\ldots|, |\cdots|, |\vdots|, |\ddots|,
+% |\iddots|\footnote{The command |\iddots| is not a command of LaTeX but is
+% defined by the package \pkg{nicematrix}. If |mathdots| is loaded, the version
+% of |mathdots| is used.} and |\hdotsfor| are redefined within the environments
+% provided by \pkg{nicematrix} and behave like |\Ldots|, |\Cdots|, |\Vdots|,
+% |\Ddots|, |\Iddots| and |\Hdotsfor|; the command |\dots| (``automatic dots''
+% of |amsmath|) is also redefined to behave like |\Ldots|.
+%
+% \item The option |renew-matrix|\par\nobreak 
+% With this option, the environment |{matrix}| is redefined and behave like
+% |{NiceMatrix}|, and so on for the five variants.
 % \end{itemize}
 %
 % \bigskip 
-% Therefore, with the option |transparent|, a classical code gives directly the ouput of \pkg{nicematrix}.\par\nobreak
+% Therefore, with the option |transparent|, a classical code gives directly the
+% ouput of \pkg{nicematrix}.\par\nobreak
 % \bigskip
 % \begin{scope}
 % \NiceMatrixOptions{transparent}
@@ -549,11 +583,13 @@ version 2005/12/01 or later.
 % 
 % \section{The Tikz nodes created by nicematrix}
 % 
-% The package \pkg{nicematrix} creates a Tikz node for each cell of the considered array. These nodes are used to
-% draw the dotted lines between the cells of the matrix. However, the user may wish to use directly these nodes.
-% It's possible. First, the user have to give a name to the array (with the key called |name|). Then, the nodes are
-% accessible through the names ``\textsl{name}-$i$-$j$'' where \textsl{name} is the name given to the array and
-% $i$ and $j$ the numbers of the row and the column of the considered cell.
+% The package \pkg{nicematrix} creates a Tikz node for each cell of the
+% considered array. These nodes are used to draw the dotted lines between the
+% cells of the matrix. However, the user may wish to use directly these nodes.
+% It's possible. First, the user have to give a name to the array (with the key
+% called |name|). Then, the nodes are accessible through the names
+% ``\textsl{name}-$i$-$j$'' where \textsl{name} is the name given to the array
+% and $i$ and $j$ the numbers of the row and the column of the considered cell.
 % 
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=11cm]
@@ -589,12 +625,15 @@ version 2005/12/01 or later.
 % 
 %
 % \bigskip
-% In fact, the package \pkg{nicematrix} can create ``extra nodes''. These new nodes are created if the option
-% |create-extra-nodes| is used. There are two series of extra nodes: the ``medium nodes'' and the ``large nodes''.
+% In fact, the package \pkg{nicematrix} can create ``extra nodes''. These new
+% nodes are created if the option |create-extra-nodes| is used. There are two
+% series of extra nodes: the ``medium nodes'' and the ``large nodes''.
 %
 % \medskip
-% The names of the ``medium nodes'' are constructed by adding the suffix ``|-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.
+% The names of the ``medium nodes'' are constructed by adding the suffix
+% ``|-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.
 % \[\begin{pNiceMatrix}[
 %  create-extra-nodes,
 %  code-after = {\begin{tikzpicture}
@@ -616,13 +655,15 @@ version 2005/12/01 or later.
 % a & a     & a + b  \\
 % a & a     & a 
 % \end{pNiceMatrix}\]
-% 
+%
 %
 % \medskip
-% The names of the ``large nodes'' are constructed by adding the suffix ``|-large|'' to the names of the ``normal
-% nodes''. In the following example, we have underlined the ``large nodes''. We consider that this example is
-% self-explanatory.\footnote{In the environments like |{pNiceArrayC}| and |{pNiceArrayRC}|, there is not ``large
-% nodes'' created in the exterior row and column.}
+% The names of the ``large nodes'' are constructed by adding the suffix
+% ``|-large|'' to the names of the ``normal nodes''. In the following example,
+% we have underlined the ``large nodes''. We consider that this example is
+% self-explanatory.\footnote{In the environments like |{pNiceArrayC}| and
+% |{pNiceArrayRC}|, there is not ``large nodes'' created in the exterior row and
+% column.}
 %
 % \[\begin{pNiceMatrix}[
 %  create-extra-nodes,
@@ -647,11 +688,13 @@ version 2005/12/01 or later.
 % 
 %
 % \medskip
-% The ``large nodes'' of the first column and last column may appear too small for some usage. That's why it's
-% possible to use the options |left-margin| and |right-margin| to add space on both sides of the array and also
-% space in the ``large nodes'' of the first column and last column. In the following example, we have used the
-% options |left-margin| and |right-margin|.\footnote{The options |left-margin| and |right-margin| take dimensions
-% as values but, if no value is given, the default value is used, which is |\arraycolsep|.}
+% The ``large nodes'' of the first column and last column may appear too small
+% for some usage. That's why it's possible to use the options |left-margin| and
+% |right-margin| to add space on both sides of the array and also space in the
+% ``large nodes'' of the first column and last column. In the following example,
+% we have used the options |left-margin| and |right-margin|.\footnote{The
+% options |left-margin| and |right-margin| take dimensions as values but, if no
+% value is given, the default value is used, which is |\arraycolsep|.}
 % \[\begin{pNiceMatrix}[
 %  create-extra-nodes,left-margin,right-margin,
 %  code-after = {\begin{tikzpicture}
@@ -674,9 +717,10 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}\]
 % 
 % \medskip
-% It's also possible to add more space on both side of the array with the options |extra-left-margin| and
-% |extra-right-margin|. These margins are not incorporated in the ``large nodes''. In the following example, we
-% have used |extra-left-margin| and |extra-right-margin| with the value $3$~pt.
+% It's also possible to add more space on both side of the array with the
+% options |extra-left-margin| and |extra-right-margin|. These margins are not
+% incorporated in the ``large nodes''. In the following example, we have used
+% |extra-left-margin| and |extra-right-margin| with the value $3$~pt.
 % \[\begin{pNiceMatrix}[
 %  create-extra-nodes,left-margin,right-margin,extra-right-margin=3pt,extra-left-margin=3pt,
 %  code-after = {\begin{tikzpicture}
@@ -699,7 +743,8 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}\]
 %
 % \medskip
-% In this case, if we want a control over the height of the rows, we can add a |\strut| in each row of the array.
+% In this case, if we want a control over the height of the rows, we can add a
+% |\strut| in each row of the array.
 % \[\begin{pNiceMatrix}[
 %  create-extra-nodes,left-margin,right-margin,extra-right-margin=3pt,extra-left-margin=3pt,
 %  code-after = {\begin{tikzpicture}
@@ -726,13 +771,15 @@ version 2005/12/01 or later.
 %
 % \section{The code-after}
 %
-% The option |code-after| may be used to give some code that will be excuted after the construction of the matrix
-% (and, hence, after the construction of all the Tikz nodes).
+% The option |code-after| may be used to give some code that will be excuted
+% after the construction of the matrix (and, hence, after the construction of
+% all the Tikz nodes).
 %
-% In the |code-after|, the Tikz nodes should be accessed by a name of the form $i$-$j$ (without the prefix of the
-% name of the environment).
+% In the |code-after|, the Tikz nodes should be accessed by a name of the form
+% $i$-$j$ (without the prefix of the name of the environment).
 %
-% Moreover, a special command, called |\line| is available to draw directly dotted lines between nodes.
+% Moreover, a special command, called |\line| is available to draw directly
+% dotted lines between nodes.
 %
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=12cm]
@@ -752,17 +799,21 @@ version 2005/12/01 or later.
 % \section{The environment \{NiceArray\}}
 % \label{NiceArray}
 %
-% The environment |{NiceArray}| is similar to the environment |{array}|. As for |{array}|, the mandatory argument
-% is the preamble of the array. However, for technical reasons, in this preamble, the user must use the letters
-% |L|, |C| and~|R|\footnote{The column types |L|, |C| and |R| are defined locally inside |{NiceArray}| with
-% |\newcolumntype| of \pkg{array}. This definition overrides an eventual previous definition.} instead of |l|, |c|
-% and |r|. It's possible to use the constructions \verb|w{...}{...}|, \verb|W{...}{...}|, \verb+|+, |>{...}|,
-% |<{...}|, |@{...}|, |!{...}| and |*{n}{...}| but the letters |p|, |m| and |b| should not be used.\footnote{In a
-% command |\multicolumn|, one should also use the letters |L|, |C|, |R|.}
+% The environment |{NiceArray}| is similar to the environment |{array}|. As for
+% |{array}|, the mandatory argument is the preamble of the array. However, for
+% technical reasons, in this preamble, the user must use the letters |L|, |C|
+% and~|R|\footnote{The column types |L|, |C| and |R| are defined locally inside
+% |{NiceArray}| with |\newcolumntype| of \pkg{array}. This definition overrides
+% an eventual previous definition.} instead of |l|, |c| and |r|. It's possible
+% to use the constructions \verb|w{...}{...}|, \verb|W{...}{...}|, \verb+|+,
+% |>{...}|, |<{...}|, |@{...}|, |!{...}| and |*{n}{...}| but the letters |p|,
+% |m| and |b| should not be used.\footnote{In a command |\multicolumn|, one
+% should also use the letters |L|, |C|, |R|.}
 %
 % \medskip
-% The environment |{NiceArray}| accepts the classical options |t|, |c| and |b| of |{array}| but also other options
-% defined by \pkg{nicematrix} (|renew-dots|, |columns-width|, etc.).
+% The environment |{NiceArray}| accepts the classical options |t|, |c| and |b|
+% of |{array}| but also other options defined by \pkg{nicematrix} (|renew-dots|,
+% |columns-width|, etc.).
 %
 % 
 % \vspace{1cm}
@@ -785,7 +836,8 @@ version 2005/12/01 or later.
 % \end{NiceArray}\right]$
 %
 % \vspace{1cm}
-% An example where we use |{NiceArray}| because we want to use the types |L| and |R| for the columns:
+% An example where we use |{NiceArray}| because we want to use the types |L| and
+% |R| for the columns:
 %
 % \bigskip
 % \begin{BVerbatim}[baseline=c,boxwidth=10cm]
@@ -811,12 +863,14 @@ version 2005/12/01 or later.
 %
 % The environment |{pNiceArrayC}| composes a matrix with an exterior column.
 %
-% The environment |{pNiceArrayC}| takes a mandatory argument which is the preamble of the array. The types
-% of columns available are the same as for the environment |{NiceArray}|. \textbf{However, no specification must be
-% given for the last column.} It will automatically (and necessarily) be a |L|~column. 
+% The environment |{pNiceArrayC}| takes a mandatory argument which is the
+% preamble of the array. The types of columns available are the same as for the
+% environment |{NiceArray}|. \textbf{However, no specification must be given for
+% the last column.} It will automatically (and necessarily) be a |L|~column.
 % 
-% A special option, called |code-for-last-col|, specifies tokens that will be inserted before each cell of the last
-% column. The option |columns-width| doesn't apply to this external column.
+% A special option, called |code-for-last-col|, specifies tokens that will be
+% inserted before each cell of the last column. The option |columns-width|
+% doesn't apply to this external column.
 % 
 % \bigskip
 %
@@ -842,10 +896,11 @@ version 2005/12/01 or later.
 % 
 %
 % \bigskip
-% In fact, the environment |{pNiceArrayC}| and its variants are based upon a more general environment, called
-% |{NiceArrayCwithDelims}|. The first two mandatory arguments of this environment are the left and right delimiters
-% used in the construction of the matrix. It's possible to use |{NiceArrayCwithDelims}| if we want to use atypical
-% delimiters.
+% In fact, the environment |{pNiceArrayC}| and its variants are based upon a
+% more general environment, called |{NiceArrayCwithDelims}|. The first two
+% mandatory arguments of this environment are the left and right delimiters used
+% in the construction of the matrix. It's possible to use
+% |{NiceArrayCwithDelims}| if we want to use atypical delimiters.
 %
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=11cm]
@@ -867,14 +922,16 @@ version 2005/12/01 or later.
 % \section{The environment \{pNiceArrayRC\} and its variants} 
 % \label{pNiceArrayRC}
 %
-% The environment |{pNiceArrayRC}| composes a matrix with an exterior row and an exterior column.
+% The environment |{pNiceArrayRC}| composes a matrix with an exterior row and an
+% exterior column.
 %
-% This environment |{pNiceArrayRC}| takes a mandatory argument which is the preamble of the array. As for the
-% environment |{pNiceArrayC}|, no specification must be given for the last column (it will automatically be a |L|
-% column). 
+% This environment |{pNiceArrayRC}| takes a mandatory argument which is the
+% preamble of the array. As for the environment |{pNiceArrayC}|, no
+% specification must be given for the last column (it will automatically be a
+% |L| column).
 %
-% A special option, called |code-for-first-row|, specifies tokens that will be inserted before each cell of the
-% first row.
+% A special option, called |code-for-first-row|, specifies tokens that will be
+% inserted before each cell of the first row.
 %
 % \bigskip
 % \begin{BVerbatim}[baseline=c,boxwidth=11cm]
@@ -899,17 +956,19 @@ version 2005/12/01 or later.
 %
 %
 % \bigskip
-% The first row of an environment |{pNiceArrayRC}| has the number $0$, and not $1$. This number is used for the
-% names of the Tikz nodes (the names of these nodes are used, for example, by the command |\line| in |code-after|).
+% The first row of an environment |{pNiceArrayRC}| has the number $0$, and not
+% $1$. This number is used for the names of the Tikz nodes (the names of these
+% nodes are used, for example, by the command |\line| in |code-after|).
 %
-% For technical reasons, it's not possible to use the option of the command |\\| after the first row (the placement
-% of the delimiters would be wrong).
+% For technical reasons, it's not possible to use the option of the command |\\|
+% after the first row (the placement of the delimiters would be wrong).
 %
 % \bigskip
-% In fact, the environment |{pNiceArrayRC}| and its variants are based upon an more general environment, called
-% |{NiceArrayRCwithDelims}|. The first two mandatory arguments of this environment are the left and right delimiters
-% used in the construction of the matrix. It's possible to use |{NiceArrayRCwithDelims}| if we want to use atypical
-% delimiters.
+% In fact, the environment |{pNiceArrayRC}| and its variants are based upon an
+% more general environment, called |{NiceArrayRCwithDelims}|. The first two
+% mandatory arguments of this environment are the left and right delimiters used
+% in the construction of the matrix. It's possible to use
+% |{NiceArrayRCwithDelims}| if we want to use atypical delimiters.
 %
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=11cm]
@@ -931,7 +990,8 @@ version 2005/12/01 or later.
 %
 %
 % \bigskip
-% If we want to write a linear system, we can use the following code, with a preamble \verb+CCC|C+:
+% If we want to write a linear system, we can use the following code, with a
+% preamble \verb+CCC|C+:
 %
 % \medskip 
 % \begin{BVerbatim}[baseline=c,boxwidth=11cm]
@@ -950,8 +1010,9 @@ version 2005/12/01 or later.
 % \end{pNiceArrayRC}$
 % 
 % \medskip
-% The resultat may seem disappointing. It's possible to suppress the vertical rule in the first row with the
-% command |\multicolumn| in order to ``reconstruct'' the cell.
+% The resultat may seem disappointing. It's possible to suppress the vertical
+% rule in the first row with the command |\multicolumn| in order to
+% ``reconstruct'' the cell.
 % 
 %
 % \bigskip
@@ -971,8 +1032,9 @@ version 2005/12/01 or later.
 % \end{pNiceArrayRC}$
 %
 % \bigskip
-% On the other side, we may remark that an horizontal line (with |\hline| or |\hdashline| of \pkg{arydshln})
-% doesn't extend in the ``exterior column'' of an environment like |{pNiceArrayC}| or |{pNiceArrayRC}|.
+% On the other side, we may remark that an horizontal line (with |\hline| or
+% |\hdashline| of \pkg{arydshln}) doesn't extend in the ``exterior column'' of
+% an environment like |{pNiceArrayC}| or |{pNiceArrayRC}|.
 %
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=11cm]
@@ -1015,8 +1077,8 @@ version 2005/12/01 or later.
 %
 %
 % \bigskip
-% It's also possible to fix the width of all the columns of a matrix directly with the option |columns-width| (in
-% all the environments of \pkg{nicematrix}).
+% It's also possible to fix the width of all the columns of a matrix directly
+% with the option |columns-width| (in all the environments of \pkg{nicematrix}).
 % 
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=10cm]
@@ -1033,11 +1095,13 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}$
 %
 % \medskip
-% Note that the space inserted between two columns (equal to 2 |\arraycolsep|) is not suppressed.
+% Note that the space inserted between two columns (equal to 2 |\arraycolsep|)
+% is not suppressed.
 %
 % \bigskip
-% It's possible to give the value |auto| to the option |columns-width|: all the columns of the array will
-% have a width equal to the widest cell of the array. \textbf{Two or three compilations may be necessary.}\par\nobreak
+% It's possible to give the value |auto| to the option |columns-width|: all the
+% columns of the array will have a width equal to the widest cell of the array.
+% \textbf{Two or three compilations may be necessary.}\par\nobreak
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=10cm]
 % $\begin{pNiceMatrix}[~emphase#columns-width = auto@]
@@ -1053,8 +1117,8 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}$
 % 
 % \bigskip
-% It's possible to fix the width of the columns of all the matrices of a current scope with the command
-% |\NiceMatrixOptions|.\par\nobreak 
+% It's possible to fix the width of the columns of all the matrices of a current
+% scope with the command |\NiceMatrixOptions|.\par\nobreak
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=8.5cm]
 % ~emphase#\NiceMatrixOptions{columns-width=10mm}@
@@ -1081,10 +1145,11 @@ version 2005/12/01 or later.
 % 
 % 
 % \bigskip
-% But it's also possible to fix a zone where all the matrices will have their columns of the same width, equal to
-% the widest cell of all the matrices. This construction uses the environment |{NiceMatrixBlock}| with the option
-% |auto-columns-width|.\footnote{At this time, this is the only usage of the environment |{NiceMatrixBlock}| but
-% it may have other usages in the future.}
+% But it's also possible to fix a zone where all the matrices will have their
+% columns of the same width, equal to the widest cell of all the matrices. This
+% construction uses the environment |{NiceMatrixBlock}| with the option
+% |auto-columns-width|.\footnote{At this time, this is the only usage of the
+% environment |{NiceMatrixBlock}| but it may have other usages in the future.}
 %
 % \medskip
 % \begin{BVerbatim}[baseline=c,boxwidth=8.5cm]
@@ -1113,11 +1178,13 @@ version 2005/12/01 or later.
 %
 % \subsection{Diagonal lines} 
 %
-% By default, all the diagonal lines\footnote{We speak of the lines created by |\Ddots| and not the lines created
-% by a command |\line| in |code-after|.} of a same array are ``parallelized''. That means that the first diagonal
-% line is drawn and, then, the other lines are drawn parallel to the first one (by rotation around the left-most
-% extremity of the line). That's why the position of the instructions |\Ddots| in the array can have a marked
-% effect on the final result.
+% By default, all the diagonal lines\footnote{We speak of the lines created by
+% |\Ddots| and not the lines created by a command |\line| in |code-after|.} of a
+% same array are ``parallelized''. That means that the first diagonal line is
+% drawn and, then, the other lines are drawn parallel to the first one (by
+% rotation around the left-most extremity of the line). That's why the position
+% of the instructions |\Ddots| in the array can have a marked effect on the
+% final result.
 %
 % \medskip
 % In the following examples, the first |\Ddots| instruction is written in color:
@@ -1162,7 +1229,8 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}$
 %
 % \bigskip
-% It's possible to turn off the parallelization with the option |parallelize-diags| set to |false|: \par\nobreak 
+% It's possible to turn off the parallelization with the option
+% |parallelize-diags| set to |false|: \par\nobreak
 %
 % \medskip
 % \NiceMatrixOptions{parallelize-diags=false}%
@@ -1182,9 +1250,11 @@ version 2005/12/01 or later.
 % \subsection{The ``empty'' cells}
 % 
 % \label{empty-cells}
-% An instruction like |\Ldots|, |\Cdots|, etc. tries to determine the first non-empty cells on both sides. However,
-% a empty cell is not necessarily a cell with no TeX content (that is to say a cell with no token between the two
-% ampersands~|&|). Indeed, a cell with contents |\hspace*{1cm}| may be considered as empty.
+% An instruction like |\Ldots|, |\Cdots|, etc. tries to determine the first
+% non-empty cells on both sides. However, a empty cell is not necessarily a cell
+% with no TeX content (that is to say a cell with no token between the two
+% ampersands~|&|). Indeed, a cell with contents |\hspace*{1cm}| may be
+% considered as empty.
 %
 % \interitem
 % For \pkg{nicematrix}, the precise rules are as follow.
@@ -1205,35 +1275,43 @@ version 2005/12/01 or later.
 % \item Each cell whose TeX ouput has a width less than 0.5~pt is empty.
 %
 % \medskip
-% \item A cell which contains a command |\Ldots|, |\Cdots|, |\Vdots|, |\Ddots| or |\Iddots| and their starred
-% versions is empty. We recall that these commands should be used alone in a cell.
+% \item A cell which contains a command |\Ldots|, |\Cdots|, |\Vdots|, |\Ddots|
+% or |\Iddots| and their starred versions is empty. We recall that these
+% commands should be used alone in a cell.
 %
 % \medskip
-% \item A cell with a command |\Hspace| (or |\Hspace*|) is empty. This command |\Hspace| is a command defined by
-% the package \pkg{nicematrix} with the same meaning as |\hspace| except that the cell where it is used is
-% considered as empty. This command can be used to fix the width of some columns of the matrix without interfering
-% with \pkg{nicematrix}.
+% \item A cell with a command |\Hspace| (or |\Hspace*|) is empty. This command
+% |\Hspace| is a command defined by the package \pkg{nicematrix} with the same
+% meaning as |\hspace| except that the cell where it is used is considered as
+% empty. This command can be used to fix the width of some columns of the matrix
+% without interfering with \pkg{nicematrix}.
 % % \end{itemize}
 %
 %
 % \subsection{The option exterior-arraycolsep}
 % 
-% The environment |{array}| inserts an horizontal space equal to |\arraycolsep| before and after each column. In
-% particular, there is a space equal to |\arraycolsep| before and after the array. This feature of the environment
-% |{array}| was probably not a good idea.\footnote{In the documentation of |{amsmath}|, we can read: {\itshape The
-% extra space of |\arraycolsep| that \pkg{array} adds on each side is a waste so we remove it [in |{matrix}|]
-% (perhaps we should instead remove it from array in general, but that's a harder task).} It's possible to suppress
-% these spaces for a given environment |{array}| with a construction like |\begin{array}{@{}ccccc@{}}|.}
+% The environment |{array}| inserts an horizontal space equal to |\arraycolsep|
+% before and after each column. In particular, there is a space equal to
+% |\arraycolsep| before and after the array. This feature of the environment
+% |{array}| was probably not a good idea.\footnote{In the documentation of
+% |{amsmath}|, we can read: {\itshape The extra space of |\arraycolsep| that
+% \pkg{array} adds on each side is a waste so we remove it [in |{matrix}|]
+% (perhaps we should instead remove it from array in general, but that's a
+% harder task).} It's possible to suppress these spaces for a given environment
+% |{array}| with a construction like |\begin{array}{@{}ccccc@{}}|.}
 %
-% The environment |{matrix}| and its variants (|{pmatrix}|, |{vmatrix}|, etc.) of \pkg{amsmath} prefer to delete
-% these spaces with explicit instructions |\hskip -\arraycolsep| and |{NiceArray}| does likewise.
+% The environment |{matrix}| and its variants (|{pmatrix}|, |{vmatrix}|, etc.)
+% of \pkg{amsmath} prefer to delete these spaces with explicit instructions
+% |\hskip -\arraycolsep| and |{NiceArray}| does likewise. 
 %
-% However, the user can change this behaviour with the boolean option |exterior-arraycolsep| of the command
-% |\NiceMatrixOptions|. With this option, |{NiceArray}| will insert the same horizontal spaces as the environment
-% |{array}|. 
+% However, the user can change this behaviour with the boolean option
+% |exterior-arraycolsep| of the command |\NiceMatrixOptions|. With this option,
+% |{NiceArray}| will insert the same horizontal spaces as the environment
+% |{array}|.  
 %
-% This option is only for ``compatibility'' since the package \pkg{nicematrix} provides a more precise control with
-% the options |left-margin|, |right-margin|, |extra-left-margin| and |extra-right-margin|.
+% This option is only for ``compatibility'' since the package \pkg{nicematrix}
+% provides a more precise control with the options |left-margin|,
+% |right-margin|, |extra-left-margin| and |extra-right-margin|. 
 %
 %
 % \subsection{The class option draft}
@@ -1309,16 +1387,6 @@ version 2005/12/01 or later.
 % \end{pNiceMatrix}$
 %
 %
-% \subsection{A remark concerning a bug of Tikz}
-%
-% Due to a bug in Tikz, the construction |-- cycle| in a Tikz path is incompatible with the use of |name prefix|
-% and |name suffix|.\footnote{cf. |tex.stackexchange.com/questions/327007/tikz-fill-not-being-drawn-using-named-coordinates|}
-%
-% \bigskip
-% Since |name prefix| is implicitly used in the |code-after| of \pkg{nicematrix}, it's not
-% possible to use |-- cycle| in |code-after|. 
-%
-%
 % \subsection{Compatibility with the extension dcolumn}
 %
 % \label{dcolumn}
@@ -1895,7 +1963,7 @@ version 2005/12/01 or later.
 %    \begin{macrocode}
 \RequirePackage{tikz}
 \usetikzlibrary{fit}
-\RequirePackage{expl3}[2018-01-01]
+\RequirePackage{expl3}[2019/02/15]
 %    \end{macrocode}
 % 
 % We give the traditionnal declaration of a package written with |expl3|:
@@ -1913,52 +1981,74 @@ version 2005/12/01 or later.
 % won't draw the dotted lines if the option |draft| is used.
 %    \begin{macrocode}
 \bool_new:N \c_@@_draft_bool
-\DeclareOption {draft} {\bool_set_true:N \c_@@_draft_bool}
-\DeclareOption* {}
+\DeclareOption { draft } { \bool_set_true:N \c_@@_draft_bool }
+\DeclareOption* { }
 \ProcessOptions \relax
 %    \end{macrocode}
 %
-% The command for the treatment of the options of |\usepackage| is at the end of this package for technical reasons.
+% The command for the treatment of the options of |\usepackage| is at the end of
+% this package for technical reasons. 
 % 
 % \bigskip
 % We load \pkg{array} and \pkg{amsmath}.
 %    \begin{macrocode}
-\RequirePackage{array}
-\RequirePackage{amsmath}
-\RequirePackage{xparse}[2018-10-17]
+\RequirePackage { array }
+\RequirePackage { amsmath }
+\RequirePackage { xparse } [ 2018-10-17 ]
 %    \end{macrocode}
 %
 % \subsection{Technical  definitions}
 %
+% We test wether the current class is \cls{revtex4-1} or \cls{revtex4-2}.
 %    \begin{macrocode}
-\cs_new_protected:Nn \@@_error:n 
-        {\msg_error:nn {nicematrix} {#1}}
-\cs_new_protected:Nn \@@_error:nn
-        {\msg_error:nn {nicematrix} {#1} {#2}}
+\bool_new:N \c_@@_revtex_bool
+\@ifclassloaded { revtex4-1 }
+  { \bool_set_true:N \c_@@_revtex_bool }
+  { }
+\@ifclassloaded { revtex4-2 }
+  { \bool_set_true:N \c_@@_revtex_bool }
+  { }
 %    \end{macrocode}
 % 
-% \medskip
+%                                       
 %    \begin{macrocode}
-\cs_new_protected:Nn \@@_bool_new:N
-      {\bool_if_exist:NTF #1
-         {\bool_set_false:N #1}
-         {\bool_new:N #1}}
+\cs_new_protected:Nn \@@_error:n { \msg_error:nn { nicematrix } { #1 } }
 %    \end{macrocode}
-%                              
+%
+%    \begin{macrocode}
+\cs_new_protected:Nn \@@_error:nn { \msg_error:nn { nicematrix } { #1 } { #2 } }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_msg_new:nn { \msg_new:nnn { nicematrix } }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_msg_new:nnn { \msg_new:nnnn { nicematrix } }
+%    \end{macrocode}
+% 
+%    \begin{macrocode}
+\cs_new_protected:Npn \@@_msg_redirect_name:nn 
+  { \msg_redirect_name:nnn { nicematrix } }
+%    \end{macrocode}
+% 
+% \bigskip
 % First, we define a command |\iddots| similar to |\ddots| ($\ddots$) but with dots going forward ($\iddots$). We
 % use |\ProvideDocumentCommand| of \pkg{xparse}, and so, if the command |\iddots| has already been defined (for
 % example by the package \pkg{mathdots}), we don't define it again.
 % 
 %    \begin{macrocode}
-\ProvideDocumentCommand \iddots {}
-      {\mathinner{\mkern 1mu 
-                  \raise \p@ \hbox{.}
-                  \mkern 2mu
-                  \raise 4\p@ \hbox{.}
-                  \mkern 2mu
-                  \raise 7\p@ \vbox{\kern 7pt 
-                                    \hbox{.}}
-                  \mkern 1mu}}
+\ProvideDocumentCommand \iddots { }
+  { 
+    \mathinner
+      { \mkern 1 mu 
+        \raise \p@ \hbox { . }
+        \mkern 2 mu
+        \raise 4 \p@ \hbox { . }
+        \mkern 2 mu
+        \raise 7 \p@ \vbox { \kern 7 pt \hbox { . } } \mkern 1 mu 
+      } 
+  }
 %    \end{macrocode}
 %
 % This definition is a variant of the standard definition of |\ddots|.
@@ -1979,103 +2069,127 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \bigskip
-% The sequence |\g_@@_names_seq| will be the list of all the names of environments used (via the option |name|) in
-% the document: two environments must not have the same name.
+% The sequence |\g_@@_names_seq| will be the list of all the names of
+% environments used (via the option |name|) in the document: two environments
+% must not have the same name. However, it's possible to use the option
+% |allow-duplicate-names|.
 %    \begin{macrocode}
 \seq_new:N \g_@@_names_seq
 %    \end{macrocode}
 %
 % \bigskip
-% The integer |\l_@@_nb_first_row_int| is the number of the first row of the array. The default value is $1$, but,
-% in the environments like |{pNiceArrayRC}|, the value will be~$0$.
+% The integer |\l_@@_nb_first_row_int| is the number of the first row of the
+% array. The default value is $1$, but, in the environments like
+% |{pNiceArrayRC}|, the value will be~$0$. 
 %    \begin{macrocode}
 \int_new:N \l_@@_nb_first_row_int
 \int_set:Nn \l_@@_nb_first_row_int 1
 %    \end{macrocode}
 % 
 % \bigskip
-% The flag |\l_@@_exterior_column_bool| will indicate if we are in an environment of the type of |{pNiceArrayC}| or
-% |{pNiceArrayRC}|. It will be used for the creation of the ``large nodes''.
+% The flag |\l_@@_exterior_column_bool| will indicate if we are in an
+% environment of the type of |{pNiceArrayC}| or |{pNiceArrayRC}|. It will be
+% used for the creation of the ``large nodes''. 
 %    \begin{macrocode}
 \bool_new:N \l_@@_exterior_column_bool
 %    \end{macrocode}
 % 
+%
+% \bigskip
+% We want to known if we are in a environment |{NiceArray}| because we want to
+% raise an error if the user tries to use nested environments |{NiceArray}|.
+%    \begin{macrocode}
+\bool_new:N \l_@@_in_NiceArray_bool
+%    \end{macrocode}
+% 
 % \bigskip 
 % \subsection{The options}
 %
-% The token list |\l_@@_pos_env_tl| will contain one of the three values |t|, |c| or |b| and will indicate the
-% position of the environment as in the option of the environment |{array}|. For the environment |{pNiceMatrix}|,
-% |{pNiceArrayC}|, |{pNiceArrayRC}| and their variants, the value will programmatically be fixed to |c|. For the
-% environment |{NiceArray}|, however, the three values |t|, |c| and |b| are possible.
+% The token list |\l_@@_pos_env_str| will contain one of the three values |t|,
+% |c| or |b| and will indicate the position of the environment as in the option
+% of the environment |{array}|. For the environment |{pNiceMatrix}|,
+% |{pNiceArrayC}|, |{pNiceArrayRC}| and their variants, the value will
+% programmatically be fixed to |c|. For the environment |{NiceArray}|, however,
+% the three values |t|, |c| and |b| are possible. 
 %    \begin{macrocode}
-\tl_new:N \l_@@_pos_env_tl 
-\tl_set:Nn \l_@@_pos_env_tl c
+\str_new:N \l_@@_pos_env_str 
+\str_set:Nn \l_@@_pos_env_str c
 %    \end{macrocode}
 % 
 % \bigskip
-% The flag |\l_@@_exterior_arraycolsep_bool| corresponds to the option |exterior-arraycolsep|. If this option is
-% set, a space equal to |\arraycolsep| will be put on both sides of an environment |{NiceArray}| (but neither for
-% |{NiceMatrix}|, |{pNiceArrayC}|, |{pNiceArrayRC}| and their variants even if these environments rely upon |{NiceArray}|).
+% The flag |\l_@@_exterior_arraycolsep_bool| corresponds to the option
+% |exterior-arraycolsep|. If this option is set, a space equal to |\arraycolsep|
+% will be put on both sides of an environment |{NiceArray}| (but neither for
+% |{NiceMatrix}|, |{pNiceArrayC}|, |{pNiceArrayRC}| and their variants even if
+% these environments rely upon |{NiceArray}|). 
 %    \begin{macrocode}
 \bool_new:N \l_@@_exterior_arraycolsep_bool
 %    \end{macrocode}
 %
 % \bigskip
-% The flag |\l_@@_parallelize_diags_bool| controls wether the diagonals are parallelized. The initial value
-% is~|true|.
+% The flag |\l_@@_parallelize_diags_bool| controls wether the diagonals are
+% parallelized. The initial value is~|true|.
 %    \begin{macrocode}
 \bool_new:N \l_@@_parallelize_diags_bool
 \bool_set_true:N \l_@@_parallelize_diags_bool
 %    \end{macrocode}
 %
 % \bigskip
-% The flag |\l_@@_nullify_dots_bool| corresponds to the option |nullify-dots|. When the flag is down, the
-% instructions like |\vdots| are inserted within a |\hphantom| (and so the constructed matrix has exactly the same
-% size as a matrix constructed with the classical |{matrix}| and |\ldots|, |\vdots|, etc.)
+% The flag |\l_@@_nullify_dots_bool| corresponds to the option |nullify-dots|.
+% When the flag is down, the instructions like |\vdots| are inserted within a
+% |\hphantom| (and so the constructed matrix has exactly the same size as a
+% matrix constructed with the classical |{matrix}| and |\ldots|, |\vdots|,
+% etc.). 
 %    \begin{macrocode}
 \bool_new:N \l_@@_nullify_dots_bool
 %    \end{macrocode}
 %
 %
 % \bigskip
-% The following flag will be used when the current options specify that all the columns of the array must have the
-% same width equal to the largest width of a cell of the array (except the cell of the ``exterior column'' of an
-% environment of the kind of |{pNiceArrayC}|).
+% The following flag will be used when the current options specify that all the
+% columns of the array must have the same width equal to the largest width of a
+% cell of the array (except the cell of the ``exterior column'' of an
+% environment of the kind of |{pNiceArrayC}|).  
 %    \begin{macrocode}
 \bool_new:N \l_@@_auto_columns_width_bool
 %    \end{macrocode}
 % 
 % \bigskip
-% The token list |\l_@@_code_for_last_col_tl| will contain code inserted at the beginning of each cell of the last
-% column in the environment |{pNiceArrayC}| (and its variants). It corresponds to the option |code-for-last-col|.
+% The token list |\l_@@_code_for_last_col_tl| will contain code inserted at the
+% beginning of each cell of the last column in the environment |{pNiceArrayC}|
+% (and its variants). It corresponds to the option |code-for-last-col|. 
 %    \begin{macrocode}
 \tl_new:N \l_@@_code_for_last_col_tl
 %    \end{macrocode}
 % 
 % \bigskip
-% We don't want to patch any existing code. That's why some code must be executed in a |\group_insert_after:N|. That's why
-% the parameters used in that code must be transfered outside the current group. To do this, we copy those
-% quantities in global variables just before the |\group_insert_after:N|. Therefore, for those quantities, we have two
-% parameters, one local and one global. For example, we have |\l_@@_name_tl| and |\g_@@_name_tl|.
+% We don't want to patch any existing code. That's why some code must be
+% executed in a |\group_insert_after:N|. That's why the parameters used in that
+% code must be transfered outside the current group. To do this, we copy those
+% quantities in global variables just before the |\group_insert_after:N|.
+% Therefore, for those quantities, we have two parameters, one local and one
+% global. For example, we have |\l_@@_name_str| and |\g_@@_name_str|. 
 %
 % \bigskip
-% The token list |\l_@@_name_tl| will contain the optional name of the environment: this name can be used to
-% access to the Tikz nodes created in the array from outside the environment. 
+% The token list |\l_@@_name_str| will contain the optional name of the
+% environment: this name can be used to access to the Tikz nodes created in the
+% array from outside the environment.  
 %    \begin{macrocode}
-\tl_new:N \g_@@_name_tl
-\tl_new:N \l_@@_name_tl
+\str_new:N \g_@@_name_str
+\str_new:N \l_@@_name_str
 %    \end{macrocode}
 %
 % \bigskip
-% The boolean |\l_@@_extra_nodes_bool| will be used to indicate wether the ``medium nodes'' and ``large nodes'' are
-% created in the array. 
+% The boolean |\l_@@_extra_nodes_bool| will be used to indicate wether the
+% ``medium nodes'' and ``large nodes'' are created in the array. 
 %    \begin{macrocode}
 \bool_new:N \l_@@_extra_nodes_bool
 \bool_new:N \g_@@_extra_nodes_bool
 %    \end{macrocode}
 %
 % \bigskip
-% The dimensions |\l_@@_left_margin_dim| and |\l_@@_right_margin_dim| correspond to the options |left-margin| and |right-margin|.
+% The dimensions |\l_@@_left_margin_dim| and |\l_@@_right_margin_dim| correspond
+% to the options |left-margin| and |right-margin|. 
 %    \begin{macrocode}
 \dim_new:N \l_@@_left_margin_dim
 \dim_new:N \l_@@_right_margin_dim
@@ -2084,8 +2198,9 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %                              
 % \bigskip
-% The dimensions |\l_@@_extra_left_margin_dim| and |\l_@@_extra_right_margin_dim| correspond to the options
-% |extra-left-margin| and |extra-right-margin|. 
+% The dimensions |\l_@@_extra_left_margin_dim| and
+% |\l_@@_extra_right_margin_dim| correspond to the options |extra-left-margin|
+% and |extra-right-margin|.  
 %    \begin{macrocode}
 \dim_new:N \l_@@_extra_left_margin_dim
 \dim_new:N \l_@@_extra_right_margin_dim
@@ -2094,746 +2209,900 @@ version 2005/12/01 or later.
 % 
 % 
 % \bigskip
-% We define a set of options which will be used with the command |NiceMatrixOptions|.\footnote{Before the version
-% 1.3, the names of the options were in ``camel-case style'' (like |ParallelizeDiagonals|) which was not a good idea. In
-% version 1.4, the names are converted in lowercase with hyphens (like |parallelize-diags|). For compatibility, the
-% old names are conversed.}
+% First, we define a set of keys ``|NiceMatrix / Global|'' which will be used
+% (with the mechanism of |.inherit:n| by other keys of set).
 %    \begin{macrocode}
-\keys_define:nn {NiceMatrix/NiceMatrixOptions}
-     {parallelize-diags    .bool_set:N = \l_@@_parallelize_diags_bool,
-      parallelize-diags    .default:n  = true,
-      ParallelizeDiagonals .meta:n = parallelize-diags,
+\keys_define:nn { NiceMatrix / Global }
+  {
+    parallelize-diags .bool_set:N = \l_@@_parallelize_diags_bool ,
+    parallelize-diags .default:n = true ,
 %    \end{macrocode}
 %
 % \bigskip
-% With the option |renew-dots|, the command |\cdots|, |\ldots|, |\vdots| and |\ddots| are redefined and behave like the
-% commands |\Cdots|, |\Ldots|, |\Vdots| and |\Ddots|.
+% With the option |renew-dots|, the command |\cdots|, |\ldots|, |\vdots| and
+% |\ddots| are redefined and behave like the commands |\Cdots|, |\Ldots|,
+% |\Vdots| and |\Ddots|. 
 %    \begin{macrocode}
-      renew-dots        .bool_set:N = \l_@@_renew_dots_bool,
-      renew-dots        .default:n  = true,
-      RenewDots         .meta:n = renew-dots,
+    renew-dots .bool_set:N = \l_@@_renew_dots_bool ,
+    renew-dots .default:n = true ,
+    nullify-dots .bool_set:N = \l_@@_nullify_dots_bool ,
+    nullify-dots .default:n = true ,
 %    \end{macrocode}
 %
 % \bigskip
-% With the option |renew-matrix|, the environment |{matrix}| of \pkg{amsmath} and its variants are redefined to
-% behave like the environment |{NiceMatrix}| and its variants.
-%    \begin{macrocode}
-      renew-matrix      .code:n     = \@@_renew_matrix:,
-      renew-matrix      .value_forbidden:n = true,
-      RenewMatrix       .meta:n     = renew-matrix,
-      transparent       .meta:n     = {renew-dots,renew-matrix},
-      transparent       .value_forbidden:n = true,
-      Transparent       .meta:n     = transparent,
+% An option to test wether the extra nodes will be created (these nodes are the
+% ``medium nodes'' and ``large nodes''). In some circonstancies, the extra nodes
+% are created automatically, for example when a dotted line has an ``open''
+% extremity. 
+%    \begin{macrocode}
+    create-extra-nodes .bool_set:N = \l_@@_extra_nodes_bool ,
+    create-extra-nodes .default:n = true,
+    left-margin .dim_set:N = \l_@@_left_margin_dim ,
+    left-margin .default:n = \arraycolsep ,
+    right-margin .dim_set:N = \l_@@_right_margin_dim ,
+    right-margin .default:n = \arraycolsep ,
+    extra-left-margin .dim_set:N = \l_@@_extra_left_margin_dim ,
+    extra-right-margin .dim_set:N = \l_@@_extra_right_margin_dim 
+  }
 %    \end{macrocode}
 %
 % \bigskip
-% Without the option |nullify-dots|, the instructions like |\vdots| are inserted within a
-% |\hphantom| (and so the constructed matrix has exactly the same size as a matrix constructed with the
-% classical |{matrix}| and |\ldots|, |\vdots|, etc.). This option is set by default.
-%    \begin{macrocode}
-      nullify-dots      .bool_set:N = \l_@@_nullify_dots_bool ,
-      nullify-dots      .default:n  = true,
-      NullifyDots       .meta:n     = nullify-dots,
+% We define a set of keys used by the environments (and not by the command
+% |\NiceMatrixOptions|). 
+%    \begin{macrocode}
+\keys_define:nn { NiceMatrix / Env }
+  {
+    columns-width .code:n = 
+      \str_if_eq:nnTF { #1 } { auto }
+        { \bool_set_true:N \l_@@_auto_columns_width_bool }
+        { \dim_set:Nn \l_@@_columns_width_dim { #1 } } , 
+    columns-width .value_required:n = true ,
+    name .code:n = 
+      \seq_if_in:NnTF \g_@@_names_seq { #1 }
+         { \@@_error:nn { Duplicate~name } { #1 } }
+         { \seq_gput_left:Nn \g_@@_names_seq { #1 } }
+      \str_set:Nn \l_@@_name_str { #1 } ,
+    name .value_required:n = true ,
+    code-after .tl_set:N = \l_@@_code_after_tl ,
+    code-after .initial:n = \c_empty_tl ,
+    code-after .value_required:n = true ,
+  }
 %    \end{macrocode}
-%
 % 
 % \bigskip
-% The following option is only for the environment |{pNiceArrayC}| and its variants. It will contain code inserted
-% at the beginning of each cell of the last column.\footnote{In an environment |{pNiceArrayC}|, the last column is
+% We begin the construction of the major sets of keys (used by the differents
+% user commands and environments). 
+%    \begin{macrocode}
+\keys_define:nn { NiceMatrix }
+  { 
+    NiceMatrixOptions .inherit:n = NiceMatrix / Global ,
+    NiceMatrix .inherit:n = 
+      { 
+        NiceMatrix / Global ,
+        NiceMatrix / Env 
+      } ,
+    NiceArray .inherit:n = 
+      { 
+        NiceMatrix / Global ,
+        NiceMatrix / Env 
+      } ,
+    NiceArrayC .inherit:n = 
+      { 
+        NiceMatrix / Global ,
+        NiceMatrix / Env 
+       } ,
+    NiceArrayRC .inherit:n = 
+      { 
+        NiceMatrix / Global ,
+        NiceMatrix / Env 
+      } 
+  }
+%    \end{macrocode}
+% 
+%
+% \bigskip
+% We finalise the definition of the set of keys 
+% ``|NiceMatrix / NiceMatrixOptions|'' with the options specific to
+% |\NiceMatrixOptions|. 
+%    \begin{macrocode}
+\keys_define:nn { NiceMatrix / NiceMatrixOptions }
+  { 
+%    \end{macrocode}
+%                              
+% With the option |renew-matrix|, the environment |{matrix}| of \pkg{amsmath}
+% and its variants are redefined to behave like the environment |{NiceMatrix}|
+% and its variants. 
+%    \begin{macrocode}
+    renew-matrix .code:n = \@@_renew_matrix: ,
+    renew-matrix .value_forbidden:n = true ,
+    RenewMatrix .meta:n = renew-matrix ,
+    transparent .meta:n = { renew-dots , renew-matrix } ,
+    transparent .value_forbidden:n = true,
+    Transparent .meta:n = transparent,
+%    \end{macrocode}
+%                              
+% \bigskip
+% The following option is only for the environment |{pNiceArrayC}| and its
+% variants. It will contain code inserted at the beginning of each cell of the
+% last column.\footnote{In an environment |{pNiceArrayC}|, the last column is 
 % composed outside the parentheses of the array.}
 %    \begin{macrocode}
-      code-for-last-col  .tl_set:N         = \l_@@_code_for_last_col_tl,
-      code-for-last-col  .value_required:n = true,
-%    \end{macrocode}  
+    code-for-last-col .tl_set:N = \l_@@_code_for_last_col_tl ,
+    code-for-last-col .value_required:n = true ,
+%    \end{macrocode}   
 %
 % \bigskip
 % Idem for the first row in environments like |{pNiceArrayRC}|.
 %    \begin{macrocode}
-      code-for-first-row   .tl_set:N   = \l_@@_code_for_first_row_tl,
-      code-for-first-row    .value_required:n = true,
+    code-for-first-row .tl_set:N = \l_@@_code_for_first_row_tl ,
+    code-for-first-row .value_required:n = true ,
 %    \end{macrocode}
 %
 % \bigskip
-% The option |exterior-arraycolsep| will have effect only in |{NiceArray}| for those who want to have for
-% |{NiceArray}| the same behaviour as |{array}|.
+% The option |exterior-arraycolsep| will have effect only in |{NiceArray}| for
+% those who want to have for |{NiceArray}| the same behaviour as |{array}|.
 %    \begin{macrocode}
-      exterior-arraycolsep .bool_set:N = \l_@@_exterior_arraycolsep_bool ,
-      exterior-arraycolsep .default:n  = true,
+    exterior-arraycolsep .bool_set:N = \l_@@_exterior_arraycolsep_bool ,
+    exterior-arraycolsep .default:n  = true ,
 %    \end{macrocode}
 %
 % \bigskip
-% If the option |columns-width| is used, all the columns will have the same width. 
+% If the option |columns-width| is used, all the columns will have the same
+% width.  
 %
 % In |\NiceMatrixOptions|, the special value |auto| is not available.
 %    \begin{macrocode}
-      columns-width     .code:n    = \str_if_eq:nnTF {#1} {auto}
-                                     {\@@_error:n {Option~auto~for~columns-width}}
-                                     {\dim_set:Nn \l_@@_columns_width_dim {#1}},
+    columns-width .code:n = 
+      \str_if_eq:nnTF { #1 } { auto }
+        { \@@_error:n { Option~auto~for~columns-width } }
+        { \dim_set:Nn \l_@@_columns_width_dim { #1 } } ,
 %    \end{macrocode}
 %
 % \bigskip
 %    \begin{macrocode}
-      create-extra-nodes  .bool_set:N   = \l_@@_extra_nodes_bool,
-      create-extra-nodes  .default:n    = true,
+    allow-duplicate-names .code:n = 
+      \@@_msg_redirect_name:nn { Duplicate~name } {none} ,
+    allow-duplicate-names .value_forbidden:n = true ,
 %    \end{macrocode}
 %
-%
 % \bigskip
 %    \begin{macrocode}
-      left-margin  .dim_set:N  = \l_@@_left_margin_dim,
-      left-margin  .default:n  = \arraycolsep,
-      right-margin .dim_set:N  = \l_@@_right_margin_dim,
-      right-margin  .default:n  = \arraycolsep,
+    unknown .code:n  = \@@_error:n { Unknown~key~for~NiceMatrixOptions } }
 %    \end{macrocode}
 %
 % \bigskip
 %    \begin{macrocode}
-      unknown .code:n  = \@@_error:n {Unknown~key~for~NiceMatrixOptions}}
-%    \end{macrocode}
-%    \begin{macrocode}
-\msg_new:nnnn {nicematrix}
-              {Unknown~key~for~NiceMatrixOptions}
-              {The~key~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~command~
-               \token_to_str:N \NiceMatrixOptions.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~keys,~type~H~<return>.}
-              {The~available~keys~are~(in~alphabetic~order):~
-               code-for-last-col,~
-               exterior-arraycolsep,~
-               left-margin,~
-               nullify-dots,~
-               parallelize-diags,~
-               renew-dots,~
-               renew-matrix,~
-               right-margin,~
-               and~transparent}
+\@@_msg_new:nnn { Unknown~key~for~NiceMatrixOptions }
+  {
+    The~key~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~command~
+    \token_to_str:N \NiceMatrixOptions. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~keys,~type~H~<return>.
+  }
+  { 
+    The~available~keys~are~(in~alphabetic~order):~
+    allow-duplicate-names,~
+    code-for-last-col,~
+    exterior-arraycolsep,~
+    left-margin,~
+    nullify-dots,~
+    parallelize-diags,~
+    renew-dots,~
+    renew-matrix,~
+    right-margin,~
+    and~transparent
+  }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\msg_new:nnn {nicematrix}
-             {Option~auto~for~columns-width}
-             {You~can't~give~the~value~"auto"~to~the~option~"columns-width"~here.~
-              If~you~go~on,~the~option~will~be~ignored.}
+\@@_msg_new:nn { Option~auto~for~columns-width }
+  { 
+    You~can't~give~the~value~'auto'~to~the~option~'columns-width'~here.~
+    If~you~go~on,~the~option~will~be~ignored.
+  }
 %    \end{macrocode}
 % 
 % \bigskip
-% |\NiceMatrixOptions| is the command of the \pkg{nicematrix} package to fix options at the document level. The
-% scope of these specifications is the current TeX group.
+% |\NiceMatrixOptions| is the command of the \pkg{nicematrix} package to fix
+% options at the document level. The scope of these specifications is the
+% current TeX group. 
 %    \begin{macrocode}
-\NewDocumentCommand \NiceMatrixOptions {m}
-    {\keys_set:nn {NiceMatrix/NiceMatrixOptions} {#1}}
+\NewDocumentCommand \NiceMatrixOptions { m }
+  { \keys_set:nn { NiceMatrix / NiceMatrixOptions } { #1 } }
 %    \end{macrocode}
 %
-% 
+%
 % \bigskip
+% We finalise the definition of the set of keys 
+% ``|NiceMatrix / NiceMatrix|'' with the options specific to |{NiceMatrix}|.
+%
 %    \begin{macrocode}
-\keys_define:nn {NiceMatrix/NiceMatrix}
-     {parallelize-diags .bool_set:N  = \l_@@_parallelize_diags_bool,
-      parallelize-diags .default:n   = true,
-      renew-dots        .bool_set:N  = \l_@@_renew_dots_bool,
-      renew-dots        .default:n   = true,
-      nullify-dots      .bool_set:N  = \l_@@_nullify_dots_bool ,
-      nullify-dots      .default:n   = true,
-%    \end{macrocode}
-% The option |columns-width| is the width of the columns if we want the same width for all the columns of the
-% array. A value of 0~pt means that the width of the column will be the natural width of the column.
-%    \begin{macrocode}
-      columns-width     .code:n      = \str_if_eq:nnTF {#1} {auto}
-                                           {\bool_set_true:N 
-                                                \l_@@_auto_columns_width_bool}
-                                           {\dim_set:Nn \l_@@_columns_width_dim {#1}},
-      name    .code:n                = {\seq_if_in:NnTF \g_@@_names_seq {#1}
-                                           {\@@_error:nn {Duplicate~name} {#1}}
-                                           {\seq_gput_left:Nn \g_@@_names_seq {#1}}
-                                        \tl_set:Nn \l_@@_name_tl {#1}},
-      name    .value_required:n      = true,
-      code-after         .tl_set:N     = \l_@@_code_after_tl,
-      code-after         .initial:n    = \c_empty_tl,
-      code-after         .value_required:n = true,
-%    \end{macrocode}
-%
-% The key |create-extra-nodes| indicates wether the ``medium nodes'' and ``large nodes'' will be created for each
-% cell of the array. 
-%    \begin{macrocode}
-      create-extra-nodes  .bool_set:N   = \l_@@_extra_nodes_bool,
-      create-extra-nodes  .default:n    = true,
-%    \end{macrocode}
-%
-%    \begin{macrocode}
-      left-margin  .dim_set:N  = \l_@@_left_margin_dim,
-      left-margin  .default:n  = \arraycolsep,
-      right-margin .dim_set:N  = \l_@@_right_margin_dim,
-      right-margin .default:n  = \arraycolsep,
-      extra-left-margin  .dim_set:N  = \l_@@_extra_left_margin_dim,
-      extra-right-margin .dim_set:N  = \l_@@_extra_right_margin_dim,
-      unknown .code:n  = \@@_error:n {Unknown~option~for~NiceMatrix}}
-%    \end{macrocode}
-%
-%    \begin{macrocode}
-\msg_new:nnnn {nicematrix}
-              {Unknown~option~for~NiceMatrix}
-              {The~option~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~environment~
-               \{NiceMatrix\}~and~its~variants.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~options,~type~H~<return>.}
-              {The~available~options~are~(in~alphabetic~order):~
-               code-after,~
-               columns-width,~
-               create-extra-nodes,~
-               extra-left-margin,~
-               extra-right-margin,~
-               left-margin,~
-               name,~
-               nullify-dots,~
-               parallelize-diags,~
-               renew-dots~
-               and~right-margin.}
+\keys_define:nn { NiceMatrix / NiceMatrix }
+  { unknown .code:n = \@@_error:n { Unknown~option~for~NiceMatrix } }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\@@_msg_new:nnn { Unknown~option~for~NiceMatrix }
+  { 
+    The~option~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~environment~
+    \{NiceMatrix\}~and~its~variants. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~options,~type~H~<return>.
+  }
+  { 
+    The~available~options~are~(in~alphabetic~order):~
+    code-after,~
+    columns-width,~
+    create-extra-nodes,~
+    extra-left-margin,~
+    extra-right-margin,~
+    left-margin,~
+    name,~
+    nullify-dots,~
+    parallelize-diags,~
+    renew-dots~
+    and~right-margin.
+  }
 %    \end{macrocode}
 % 
 % \bigskip
 %    \begin{macrocode}
-\msg_new:nnnn {nicematrix}
-              {Duplicate~name}
-              {The~name~"#1"~is~already~used~and~you~shouldn't~use~
-               the~same~environment~name~twice.~You~can~go~on,~but,~
-               maybe,~you~will~have~incorrect~results~especially~ 
-               if~you~use~"columns-width=auto".\\
-               For~a~list~of~the~names~already~used,~type~H~<return>.}
-              {The~names~already~defined~in~this~document~are:~
-               \seq_use:Nnnn~\g_@@_names_seq~{,~} {,~} {~and~}.}
+\@@_msg_new:nnn { Duplicate~name }
+  { 
+    The~name~'\l_keys_value_tl'~is~already~used~and~you~shouldn't~use~
+    the~same~environment~name~twice.~You~can~go~on,~but,~
+    maybe,~you~will~have~incorrect~results~especially~ 
+    if~you~use~'columns-width=auto'. \\
+    For~a~list~of~the~names~already~used,~type~H~<return>. \\ 
+    If~you~don't~want~to~see~this~message~again,~use~the~option~
+    'allow-duplicate-names'. 
+  }
+  {
+    The~names~already~defined~in~this~document~are:~
+    \seq_use:Nnnn \g_@@_names_seq { ,~ } { ,~ } { ~and~ }.
+  }
 %    \end{macrocode}
 %
 % \bigskip
+% 
+% \bigskip
+% We finalise the definition of the set of keys 
+% ``|NiceMatrix / NiceArray|'' with the options specific to |{NiceArray}|.
+%
 %    \begin{macrocode}
-\keys_define:nn {NiceMatrix/NiceArray}
-     {parallelize-diags    .bool_set:N = \l_@@_parallelize_diags_bool,
-      parallelize-diags    .default:n  = true,
-      renew-dots           .bool_set:N = \l_@@_renew_dots_bool,
-      renew-dots           .default:n  = true,
-      nullify-dots         .bool_set:N = \l_@@_nullify_dots_bool ,
-      nullify-dots         .default:n  = true,
-      columns-width        .code:n = \str_if_eq:nnTF {#1} {auto}
-                                       {\bool_set_true:N \l_@@_auto_columns_width_bool}
-                                       {\dim_set:Nn \l_@@_columns_width_dim {#1}},
-      columns-width        .value_required:n = true,
-      name                 .code:n     = {\seq_if_in:NnTF \g_@@_names_seq {#1}
-                                            {\@@_error:nn {Duplicate~name} {#1}}
-                                            {\seq_gput_left:Nn \g_@@_names_seq {#1}}
-                                          \tl_set:Nn \l_@@_name_tl {#1}},
-      name                 .value_required:n = true,
+\keys_define:nn { NiceMatrix / NiceArray }
+  {
 %    \end{macrocode}
 % 
 % \bigskip
-% The options |c|, |t| and |b| of the environment |{NiceArray}| have the same meaning as the option of the classical
-% environment |{array}|.
-%    \begin{macrocode}
-      c                  .code:n    = \tl_set:Nn \l_@@_pos_env_tl c,
-      t                  .code:n    = \tl_set:Nn \l_@@_pos_env_tl t,
-      b                  .code:n    = \tl_set:Nn \l_@@_pos_env_tl b,
-      code-after         .tl_set:N  = \l_@@_code_after_tl,
-      code-after         .initial:n = \c_empty_tl,
-      code-after         .value_required:n = true,
-      create-extra-nodes  .bool_set:N   = \l_@@_extra_nodes_bool,
-      create-extra-nodes  .default:n    = true,
-      left-margin  .dim_set:N  = \l_@@_left_margin_dim,
-      left-margin  .default:n  = \arraycolsep,
-      right-margin .dim_set:N  = \l_@@_right_margin_dim,
-      right-margin .default:n  = \arraycolsep,
-      extra-left-margin  .dim_set:N  = \l_@@_extra_left_margin_dim,
-      extra-right-margin .dim_set:N  = \l_@@_extra_right_margin_dim,
-      unknown .code:n  = \@@_error:n {Unknown~option~for~NiceArray}}
-%    \end{macrocode}
-%
-%    \begin{macrocode}
-\msg_new:nnnn {nicematrix}
-              {Unknown~option~for~NiceArray}
-              {The~option~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~environment~
-               \{NiceArray\}.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~options,~type~H~<return>.}
-              {The~available~options~are~(in~alphabetic~order):~
-               b,~
-               c,~
-               code-after,~
-               create-extra-nodes,~
-               columns-width,~
-               extra-left-margin,~
-               extra-right-margin,~
-               left-margin,~
-               name,~
-               nullify-dots,~
-               parallelize-diags,~
-               renew-dots,~
-               right-margin,~
-               and~t.}
+% The options |c|, |t| and |b| of the environment |{NiceArray}| have the same
+% meaning as the option of the classical environment |{array}|.
+%    \begin{macrocode}
+    c .code:n = \str_set:Nn \l_@@_pos_env_str c ,
+    t .code:n = \str_set:Nn \l_@@_pos_env_str t ,
+    b .code:n = \str_set:Nn \l_@@_pos_env_str b ,
+    unknown .code:n = \@@_error:n { Unknown~option~for~NiceArray } 
+  }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\@@_msg_new:nnn { Unknown~option~for~NiceArray }
+  { 
+    The~option~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~environment~
+    \{NiceArray\}. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~options,~type~H~<return>.
+  }
+  {
+    The~available~options~are~(in~alphabetic~order):~
+    b,~
+    c,~
+    code-after,~
+    create-extra-nodes,~
+    columns-width,~
+    extra-left-margin,~
+    extra-right-margin,~
+    left-margin,~
+    name,~
+    nullify-dots,~
+    parallelize-diags,~
+    renew-dots,~
+    right-margin,~
+    and~t.
+  }
 %    \end{macrocode}
 % 
 % \subsection{The environments \{NiceArray\} and \{NiceMatrix\}}
 %
-% The pseudo-environment |\@@_Cell:|--|\@@_end_Cell:| will be used to format the cells of the array. In the code,
-% the affectations are global because this pseudo-environment will be used in the cells of a |\halign| (via an
-% environment |{array}|).
+% The pseudo-environment |\@@_Cell:|--|\@@_end_Cell:| will be used to format the
+% cells of the array. In the code, the affectations are global because this
+% pseudo-environment will be used in the cells of a |\halign| (via an
+% environment |{array}|). 
 %
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_Cell:
-   { 
+  { 
 %    \end{macrocode}
 % We increment |\g_@@_column_int|, which is the counter of the columns. 
 %    \begin{macrocode}
     \int_gincr:N \g_@@_column_int
 %    \end{macrocode}
-% Now, we increment the counter of the rows. We don't do this incrementation in the |\everycr| because some
-% packages, like \pkg{arydshln}, create special rows in the |\halign| that we don't want to take into account.
+% Now, we increment the counter of the rows. We don't do this incrementation in
+% the |\everycr| because some packages, like \pkg{arydshln}, create special rows
+% in the |\halign| that we don't want to take into account. 
 %    \begin{macrocode}
-    \int_compare:nNnT \g_@@_column_int = 1
-          {\int_gincr:N \g_@@_row_int}                
+    \int_compare:nNnT \g_@@_column_int = \c_one_int
+       { \int_gincr:N \g_@@_row_int }                
     \int_gset:Nn \g_@@_column_total_int 
-                 {\int_max:nn \g_@@_column_total_int \g_@@_column_int}
+       { \int_max:nn \g_@@_column_total_int \g_@@_column_int }
     \hbox_set:Nw \l_tmpa_box $ % $ 
-    \int_compare:nNnT \g_@@_row_int = 0
-             \l_@@_code_for_first_row_tl}
+    \int_compare:nNnT \g_@@_row_int = \c_zero_int
+      \l_@@_code_for_first_row_tl
+  }
 %    \end{macrocode}
 % 
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_end_Cell:
-   {$ % $ 
+  { $ % $ 
     \hbox_set_end:
 %    \end{macrocode}
 %
-% We want to compute in |\l_@@_max_cell_width_dim| the width of the widest cell of the array (except the cells of
-% the last column of an environment of the kind of |{pNiceArrayC}|).
+% We want to compute in |\l_@@_max_cell_width_dim| the width of the widest cell
+% of the array (except the cells of the last column of an environment of the
+% kind of |{pNiceArrayC}|). 
 %    \begin{macrocode}
     \dim_gset:Nn \g_@@_max_cell_width_dim
-          {\dim_max:nn \g_@@_max_cell_width_dim {\box_wd:N \l_tmpa_box}}
+      { \dim_max:nn \g_@@_max_cell_width_dim { \box_wd:N \l_tmpa_box } }
 %    \end{macrocode}
 %
 %
 %    \begin{macrocode}
-    \int_compare:nNnT \g_@@_row_int = 0
-       {\dim_gset:Nn \g_@@_max_dp_row_zero_dim
-            {\dim_max:nn \g_@@_max_dp_row_zero_dim {\box_dp:N \l_tmpa_box}}
+    \int_compare:nNnT \g_@@_row_int = \c_zero_int
+      { 
+        \dim_gset:Nn \g_@@_max_dp_row_zero_dim
+          { \dim_max:nn \g_@@_max_dp_row_zero_dim { \box_dp:N \l_tmpa_box } }
         \dim_gset:Nn \g_@@_max_ht_row_zero_dim
-            {\dim_max:nn \g_@@_max_ht_row_zero_dim {\box_ht:N \l_tmpa_box}}}
-    \int_compare:nNnT \g_@@_row_int = 1
-       {\dim_gset:Nn \g_@@_max_ht_row_one_dim
-            {\dim_max:nn \g_@@_max_ht_row_one_dim {\box_ht:N \l_tmpa_box}}}
+          { \dim_max:nn \g_@@_max_ht_row_zero_dim { \box_ht:N \l_tmpa_box } } 
+      }
+    \int_compare:nNnT \g_@@_row_int = \c_one_int
+      { 
+        \dim_gset:Nn \g_@@_max_ht_row_one_dim
+          { \dim_max:nn \g_@@_max_ht_row_one_dim { \box_ht:N \l_tmpa_box } } 
+      }
 %    \end{macrocode}
 % 
 % Now, we can create the Tikz node of the cell.
 %    \begin{macrocode}
-    \tikz[remember~picture, inner~sep = 0pt, minimum~width = 0pt, baseline]
-       \node [anchor = base,
-              name = nm-\int_use:N \g_@@_env_int-
-                        \int_use:N \g_@@_row_int-
-                        \int_use:N \g_@@_column_int,
-              alias = \tl_if_empty:NF \l_@@_name_tl
-                         {\tl_use:N \l_@@_name_tl-
-                          \int_use:N \g_@@_row_int-
-                          \int_use:N \g_@@_column_int} ] 
-       \bgroup 
-       \box_use:N \l_tmpa_box
-       \egroup ;} 
+    \tikz 
+      [ 
+        remember~picture , 
+        inner~sep = \c_zero_dim , 
+        minimum~width = \c_zero_dim , 
+        baseline 
+      ]
+    \node 
+      [
+        anchor = base ,
+        name = nm - \int_use:N \g_@@_env_int -
+                    \int_use:N \g_@@_row_int -
+                    \int_use:N \g_@@_column_int ,
+        alias = 
+          \str_if_empty:NF \l_@@_name_str
+            { 
+              \l_@@_name_str -
+              \int_use:N \g_@@_row_int -
+              \int_use:N \g_@@_column_int
+            } 
+      ] 
+    \bgroup 
+    \box_use:N \l_tmpa_box
+    \egroup ;
+  } 
 %    \end{macrocode}
 %
 % 
 % \interitem
-% The environment |{NiceArray}| is the main environment of the extension \pkg{nicematrix}.
+% The environment |{NiceArray}| is the main environment of the extension
+% \pkg{nicematrix}. In order to clarify the explanations, we will first give the
+% definition of the environment |{NiceMatrix}|.  
 %
-% In order to clarify the explanations, we will first give the definition of the environment |{NiceMatrix}|.
-%
-% Our environment |{NiceMatrix}| must have the same second part as the environment |{matrix}| of \pkg{amsmath}
-% (because of the programmation of the option |renew-matrix|). Hence, this second part is the following:
+% Our environment |{NiceMatrix}| must have the same second part as the
+% environment |{matrix}| of \pkg{amsmath} (because of the programmation of the
+% option |renew-matrix|). Hence, this second part is the following: 
 % 
 % \begin{Verbatim}
 %          \endarray
 %          \skip_horizontal:n {-\arraycolsep}
 % \end{Verbatim}
 % 
-% That's why, in the definition of |{NiceMatrix}|, we must use |\NiceArray| and not |\begin{NiceArray}| 
-% (and, in the definition of |{NiceArray}|, we will have to use |\array|, and not |\begin{array}|: see below).
+% That's why, in the definition of |{NiceMatrix}|, we must use |\NiceArray| and
+% not |\begin{NiceArray}| (and, in the definition of |{NiceArray}|, we will have
+% to use |\array|, and not |\begin{array}|: see below). 
 % 
 % \medskip
 % Here's the definition of |{NiceMatrix}|:
 %    \begin{macrocode}
-\NewDocumentEnvironment {NiceMatrix} {!O{}}
-    {\keys_set:nn {NiceMatrix/NiceMatrix} {#1}
-     \tl_set:Nn \l_@@_pos_env_tl c
-     \bool_set_false:N \l_@@_exterior_arraycolsep_bool
-         \NiceArray{*\c@MaxMatrixCols{C}}
-      }
-    {\endarray
-     \skip_horizontal:n {-\arraycolsep}
-     \skip_horizontal:n {\g_@@_right_margin_dim + \g_@@_extra_right_margin_dim}}
+\NewDocumentEnvironment { NiceMatrix } { ! O { } }
+  { 
+    \keys_set:nn { NiceMatrix / NiceMatrix } { #1 }
+    \str_set:Nn \l_@@_pos_env_str c
+    \bool_set_false:N \l_@@_exterior_arraycolsep_bool
+    \NiceArray { * \c@MaxMatrixCols C }
+  }
+  { 
+    \endarray
+    \skip_horizontal:n 
+      { \g_@@_right_margin_dim + \g_@@_extra_right_margin_dim - \arraycolsep }  
+  }
 %    \end{macrocode}
 %
 % \interitem
-% For the definition of |{NiceArray}| (just below), we have the following constraints:
+% For the definition of |{NiceArray}| (just below), we have the following
+% constraints: 
 % \begin{itemize}
-% \item we must use |\array| in the first part of |{NiceArray}| and, therefore, |\endarray| in the second part;
-% \item we have to put a |\group_insert_after:N \@@_after_array:| in the first part of |{NiceArray}| so that |\@@_draw_lines|
-% will be executed at the end of the current environment (either |{NiceArray}| or |{NiceMatrix}|).
+% \item we must use |\array| in the first part of |{NiceArray}| and, therefore,
+% |\endarray| in the second part; 
+% \item we have to put a |\group_insert_after:N \@@_after_array:| in the first
+% part of |{NiceArray}| so that |\@@_draw_lines| will be executed at the end of
+% the current environment (either |{NiceArray}| or |{NiceMatrix}|). 
 % \end{itemize}
 %               
 %    \begin{macrocode}
-\cs_generate_variant:Nn \dim_set:Nn {Nx}
+\cs_generate_variant:Nn \dim_set:Nn { N x }
 %    \end{macrocode}
 % 
 %
 % \bigskip
 %    \begin{macrocode}
-\msg_new:nnn {nicematrix} 
-             {We~are~yet~in~an~environment~NiceArray}
-             {Environments~\{NiceArray\}~(or~\{NiceMatrix\},~etc.)~can't~be~
-              nested.~We~can~go~on,~but,~maybe,~you~will~have~errors~or~an~incorrect~
-              result.}
+\@@_msg_new:nn { Yet~in~NiceArray }
+  { 
+    Environments~\{NiceArray\}~(or~\{NiceMatrix\},~etc.)~can't~be~
+    nested.~We~can~go~on,~but,~maybe,~you~will~have~errors~or~an~incorrect~
+    result.
+  }
 %    \end{macrocode}
 %
 %
 % \bigskip
-% The command |\@@_define_dots:| will be used in the environment |{NiceArray}| to define the commands |\Ldots|,
-% |\Cdots|, etc.
+% The command |\@@_define_dots:| will be used in the environment |{NiceArray}|
+% to define the commands |\Ldots|, |\Cdots|, etc.
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_define_dots:
-    {\cs_set_eq:NN \Ldots \@@_Ldots
-     \cs_set_eq:NN \Cdots \@@_Cdots
-     \cs_set_eq:NN \Vdots \@@_Vdots
-     \cs_set_eq:NN \Ddots \@@_Ddots
-     \cs_set_eq:NN \Iddots \@@_Iddots
-     \bool_if:NT \l_@@_renew_dots_bool
-        {\cs_set_eq:NN \ldots \@@_Ldots
-         \cs_set_eq:NN \cdots \@@_Cdots
-         \cs_set_eq:NN \vdots \@@_Vdots
-         \cs_set_eq:NN \ddots \@@_Ddots
-         \cs_set_eq:NN \iddots \@@_Iddots
-         \cs_set_eq:NN \dots \@@_Ldots
-         \cs_set_eq:NN \hdotsfor \@@_Hdotsfor}}
+  { 
+    \cs_set_eq:NN \Ldots \@@_Ldots
+    \cs_set_eq:NN \Cdots \@@_Cdots
+    \cs_set_eq:NN \Vdots \@@_Vdots
+    \cs_set_eq:NN \Ddots \@@_Ddots
+    \cs_set_eq:NN \Iddots \@@_Iddots
+    \bool_if:NT \l_@@_renew_dots_bool
+      { 
+        \cs_set_eq:NN \ldots \@@_Ldots
+        \cs_set_eq:NN \cdots \@@_Cdots
+        \cs_set_eq:NN \vdots \@@_Vdots
+        \cs_set_eq:NN \ddots \@@_Ddots
+        \cs_set_eq:NN \iddots \@@_Iddots
+        \cs_set_eq:NN \dots \@@_Ldots
+        \cs_set_eq:NN \hdotsfor \@@_Hdotsfor
+      }
+  }
 %    \end{macrocode}
 %
 % \bigskip
-% With |\@@_define_dots_to_nil:|, the commands like |\Ldots|, |\Cdots|, are defined, but with no effect. This
-% command will be used if the class option |draft| is used.
+% With |\@@_define_dots_to_nil:|, the commands like |\Ldots|, |\Cdots|, are
+% defined, but with no effect. This command will be used if the class option
+% |draft| is used. 
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_define_dots_to_nil:
-    {\cs_set_eq:NN \Ldots \prg_do_nothing:
-     \cs_set_eq:NN \Cdots \prg_do_nothing:
-     \cs_set_eq:NN \Vdots \prg_do_nothing:
-     \cs_set_eq:NN \Ddots \prg_do_nothing:
-     \cs_set_eq:NN \Iddots \prg_do_nothing:
-     \bool_if:NT \l_@@_renew_dots_bool
-        {\cs_set_eq:NN \ldots \prg_do_nothing:
-         \cs_set_eq:NN \cdots \prg_do_nothing:
-         \cs_set_eq:NN \vdots \prg_do_nothing:
-         \cs_set_eq:NN \ddots \prg_do_nothing:
-         \cs_set_eq:NN \iddots \prg_do_nothing:
-         \cs_set_eq:NN \dots \prg_do_nothing:
-         \cs_set_eq:NN \hdotsfor \@@_Hdotsfor}}
-%    \end{macrocode}
-%                                                                                      
+  { 
+    \cs_set_eq:NN \Ldots \prg_do_nothing:
+    \cs_set_eq:NN \Cdots \prg_do_nothing:
+    \cs_set_eq:NN \Vdots \prg_do_nothing:
+    \cs_set_eq:NN \Ddots \prg_do_nothing:
+    \cs_set_eq:NN \Iddots \prg_do_nothing:
+    \bool_if:NT \l_@@_renew_dots_bool
+      { 
+        \cs_set_eq:NN \ldots \prg_do_nothing:
+        \cs_set_eq:NN \cdots \prg_do_nothing:
+        \cs_set_eq:NN \vdots \prg_do_nothing:
+        \cs_set_eq:NN \ddots \prg_do_nothing:
+        \cs_set_eq:NN \iddots \prg_do_nothing:
+        \cs_set_eq:NN \dots \prg_do_nothing:
+        \cs_set_eq:NN \hdotsfor \@@_Hdotsfor
+      }
+  }
+%    \end{macrocode}
+%                     
 %
 % \bigskip
-% First, we test if we are yet in an environment |{NiceArray}| (nested environment are forbidden). It's easy to
-% test whether we are in an environment |{NiceArray}| : a special command |\@@_in_NiceArray:| is defined.
+% First, we test if we are yet in an environment |{NiceArray}| (nested
+% environments are forbidden). 
 %    \begin{macrocode}
-\NewDocumentEnvironment {NiceArray} {O{} m !O{}}
-    {\cs_if_exist:NT \@@_in_NiceArray:
-           {\@@_error:n {We~are~yet~in~an~environment~NiceArray}}
+\NewDocumentEnvironment { NiceArray } { O { } m ! O { } }
+  { 
+    \bool_if:NT \l_@@_in_NiceArray_bool
+      { \@@_error:n { Yet~in~NiceArray } }
 %    \end{macrocode}
-% We deactivate Tikz externalization (since we use Tikz pictures with the options |overlay| and 
-% |remember picture|, there would be errors).
+%
+% We deactivate Tikz externalization (since we use Tikz pictures with the
+% options |overlay| and |remember picture|, there would be errors).
 %    \begin{macrocode}
-     \cs_if_exist:NT \tikz@library@external@loaded
-        {\tikzset{external/export = false}}
-     \cs_set:Npn \@@_in_NiceArray: {--Void--}
-     \group_insert_after:N \@@_after_array:
-     \tl_gclear_new:N \g_@@_lines_to_draw_tl 
+    \cs_if_exist:NT \tikz@library@external@loaded
+      { \tikzset { external / export = false } }
+    \bool_set_true:N \l_@@_in_NiceArray_bool
+    \group_insert_after:N \@@_after_array:
+    \tl_gclear_new:N \g_@@_lines_to_draw_tl 
 %    \end{macrocode}
 %
-% We increment the counter |\g_@@_env_int| which counts the environments |{NiceArray}|.
+% We increment the counter |\g_@@_env_int| which counts the environments
+% |{NiceArray}|. 
 %    \begin{macrocode}
-     \int_gincr:N \g_@@_env_int
-     \bool_if:NF \l_@@_block_auto_columns_width_bool
-              {\dim_gzero_new:N \g_@@_max_cell_width_dim}
+    \int_gincr:N \g_@@_env_int
+    \bool_if:NF \l_@@_block_auto_columns_width_bool
+      { \dim_gzero_new:N \g_@@_max_cell_width_dim }
 %    \end{macrocode}
 %
-% For the following variables, maybe we should create it only if we use the environment |{pNiceArrayRC}| or its variants.
+% For the following variables, maybe we should create it only if we use the
+% environment |{pNiceArrayRC}| or its variants. 
 %    \begin{macrocode}
-     \dim_gzero_new:N \g_@@_max_dp_row_zero_dim
-     \dim_gzero_new:N \g_@@_max_ht_row_zero_dim
-     \dim_gzero_new:N \g_@@_max_ht_row_one_dim
+    \dim_gzero_new:N \g_@@_max_dp_row_zero_dim
+    \dim_gzero_new:N \g_@@_max_ht_row_zero_dim
+    \dim_gzero_new:N \g_@@_max_ht_row_one_dim
 %    \end{macrocode}
 % 
 %    \begin{macrocode}
-     \keys_set:nn {NiceMatrix/NiceArray} {#1,#3} 
+    \keys_set:nn { NiceMatrix / NiceArray } { #1 , #3 } 
 %    \end{macrocode}
 % 
-% If the user requires all the columns to have a width equal to the widest cell of the array, we read this length in
-% the file |.aux| (of, course, this is possible only on the second run of LaTeX : on the first run, the dimension
-% |\l_@@_columns_width_dim| will be set to zero --- and the columns will have their natural width).
+% If the user requires all the columns to have a width equal to the widest cell
+% of the array, we read this length in the file |.aux| (of, course, this is
+% possible only on the second run of LaTeX : on the first run, the dimension
+% |\l_@@_columns_width_dim| will be set to zero --- and the columns will have
+% their natural width). 
 %    \begin{macrocode}
-     \bool_if:NT \l_@@_auto_columns_width_bool
-         {\group_insert_after:N \@@_write_max_cell_width:
-          \cs_if_free:cTF {_@@_max_cell_width_\int_use:N \g_@@_env_int}
-                {\dim_set:Nn \l_@@_columns_width_dim \c_zero_dim}
-                {\dim_set:Nx \l_@@_columns_width_dim 
-                     {\use:c {_@@_max_cell_width_\int_use:N \g_@@_env_int}}}
-%    \end{macrocode}
-% If the environment has a name, we read the value of the maximal value of the columns from 
-% |_@@_name_cell_width|{\ttfamily\slshape name} (the value will be the correct value even if the number of the 
-% environment has changed (for example because the user has created or deleted an environment before the current one).
-%    \begin{macrocode}
-          \tl_if_empty:NF \l_@@_name_tl
-            {\cs_if_free:cF {_@@_max_cell_width_\l_@@_name_tl}
-                {\dim_set:Nx \l_@@_columns_width_dim 
-                     {\use:c {_@@_max_cell_width_\l_@@_name_tl}}}}
-         }
+    \bool_if:NT \l_@@_auto_columns_width_bool
+      { 
+        \group_insert_after:N \@@_write_max_cell_width:
+         \cs_if_free:cTF { _@@_max_cell_width_ \int_use:N \g_@@_env_int }
+           { \dim_set:Nn \l_@@_columns_width_dim \c_zero_dim }
+           { 
+             \dim_set:Nx \l_@@_columns_width_dim 
+               { \use:c { _@@_max_cell_width _ \int_use:N \g_@@_env_int } } 
+           }
 %    \end{macrocode}
-% We don't want to patch any code and that's why some code is excuted in a |\group_insert_after:N|. In particular, in this
-% |\group_insert_after:N|, we will have to know the value of some parameters like |\l_@@_extra_nodes_bool|. That's why we transit via a global
-% version for some variables.
+% If the environment has a name, we read the value of the maximal value of the
+% columns from |_@@_name_cell_width|{\ttfamily\slshape name} (the value will be
+% the correct value even if the number of the environment has changed (for
+% example because the user has created or deleted an environment before the
+% current one). 
 %    \begin{macrocode}
-     \bool_gset_eq:NN \g_@@_extra_nodes_bool \l_@@_extra_nodes_bool
-     \dim_gset_eq:NN \g_@@_left_margin_dim \l_@@_left_margin_dim
-     \dim_gset_eq:NN \g_@@_right_margin_dim \l_@@_right_margin_dim
-     \dim_gset_eq:NN \g_@@_extra_right_margin_dim \l_@@_extra_right_margin_dim
-     \tl_gset_eq:NN \g_@@_code_after_tl \l_@@_code_after_tl
-     \tl_gset_eq:NN \g_@@_name_tl \l_@@_name_tl
+         \str_if_empty:NF \l_@@_name_str
+           { 
+             \cs_if_free:cF { _@@_max_cell_width_ \l_@@_name_str }
+               { 
+                 \dim_set:Nx \l_@@_columns_width_dim 
+                   { \use:c { _@@_max_cell_width_ \l_@@_name_str } }
+               }
+           }
+      }
 %    \end{macrocode}
-% The environment |{array}| uses internally the command |\ialign| and, in particular, this command |\ialign| sets
-% |\everycr| to |{}|. However, we want to use |\everycr| in our array.
-% The solution is to give to |\ialign| a new definition (giving to |\everycr| the value we want)
-% that will revert automatically to its default definition after the first utilisation.\footnote{With this programmation, we will
-% have, in the cells of the array, a clean version of |\ialign|. That's necessary: the user will probably not employ directly 
-% |\ialign| in the array...  but more likely environments that utilize |\ialign| internally (e.g.: |{substack}|)}
-%    \begin{macrocode}
-     \cs_set:Npn \ialign 
-          {\everycr{\noalign{\int_gzero:N \g_@@_column_int}}
-          \tabskip = \c_zero_skip
-          \cs_set:Npn \ialign {\everycr{} 
-                               \tabskip = \c_zero_skip
-                               \halign}
-          \halign}
+% We don't want to patch any code and that's why some code is excuted in a
+% |\group_insert_after:N|. In particular, in this |\group_insert_after:N|, we
+% will have to know the value of some parameters like |\l_@@_extra_nodes_bool|.
+% That's why we transit via a global version for some variables.
+%    \begin{macrocode}
+    \bool_gset_eq:NN \g_@@_extra_nodes_bool \l_@@_extra_nodes_bool
+    \dim_gset_eq:NN \g_@@_left_margin_dim \l_@@_left_margin_dim
+    \dim_gset_eq:NN \g_@@_right_margin_dim \l_@@_right_margin_dim
+    \dim_gset_eq:NN \g_@@_extra_right_margin_dim \l_@@_extra_right_margin_dim
+    \tl_gset_eq:NN \g_@@_code_after_tl \l_@@_code_after_tl
+    \tl_gset_eq:NN \g_@@_name_str \l_@@_name_str
+%    \end{macrocode}
+% The environment |{array}| uses internally the command |\ialign| and, in
+% particular, this command |\ialign| sets |\everycr| to |{}|. However, we want
+% to use |\everycr| in our array. The solution is to give to |\ialign| a new
+% definition (giving to |\everycr| the value we want) that will revert
+% automatically to its default definition after the first
+% utilisation.\footnote{With this programmation, we will have, in the cells of
+% the array, a clean version of |\ialign|. That's necessary: the user will
+% probably not employ directly |\ialign| in the array...  but more likely
+% environments that utilize |\ialign| internally (e.g.: |{substack}|)} 
+%    \begin{macrocode}
+    \cs_set:Npn \ialign 
+       { 
+         \everycr { \noalign { \int_gzero:N \g_@@_column_int } }
+         \tabskip = \c_zero_skip
+         \cs_set:Npn \ialign 
+            { 
+              \everycr { } 
+              \tabskip = \c_zero_skip
+              \halign
+            }
+         \halign 
+       }
 %    \end{macrocode}
-%                                                                                      
-% We define the new column types |L|, |C| and |R| that must be used instead of |l|, |c| and |r| in the preamble of
-% |{NiceArray}|.
+%                                                   
+% We define the new column types |L|, |C| and |R| that must be used instead of
+% |l|, |c| and |r| in the preamble of |{NiceArray}|.
 %    \begin{macrocode}
-     \dim_compare:nNnTF \l_@@_columns_width_dim = \c_zero_dim
-        {\newcolumntype{L}{>{\@@_Cell:}l<{\@@_end_Cell:}}
-         \newcolumntype{C}{>{\@@_Cell:}c<{\@@_end_Cell:}}
-         \newcolumntype{R}{>{\@@_Cell:}r<{\@@_end_Cell:}}}
+    \dim_compare:nNnTF \l_@@_columns_width_dim = \c_zero_dim
+       {
+        \newcolumntype L { > \@@_Cell: l < \@@_end_Cell: }
+        \newcolumntype C { > \@@_Cell: c < \@@_end_Cell: }
+        \newcolumntype R { > \@@_Cell: r < \@@_end_Cell: }
+       }
 %    \end{macrocode}
-% If there is an option that specify that all the columns must have the same width, the column types~|L|, |C|
-% and~|R| are in fact defined upon the column type~|w| of array which is, in fact, redefined below.
+% If there is an option that specify that all the columns must have the same
+% width, the column types~|L|, |C| and~|R| are in fact defined upon the column
+% type~|w| of \pkg{array} which is, in fact, redefined below. 
 %    \begin{macrocode}
-        {\newcolumntype{L}{wl{\dim_use:N \l_@@_columns_width_dim}}
-         \newcolumntype{C}{wc{\dim_use:N \l_@@_columns_width_dim}}
-         \newcolumntype{R}{wr{\dim_use:N \l_@@_columns_width_dim}}}
+       {
+        \newcolumntype L { w l { \dim_use:N \l_@@_columns_width_dim } }
+        \newcolumntype C { w c { \dim_use:N \l_@@_columns_width_dim } }
+        \newcolumntype R { w r { \dim_use:N \l_@@_columns_width_dim } } 
+       }
 %    \end{macrocode}
 % 
-% We nullify the definitions of the column types |w| and |W| because we want to avoid a warning in the log file
-% for a redefinition of a column type.
+% We nullify the definitions of the column types |w| and |W| because we want to
+% avoid a warning in the log file for a redefinition of a column type. We must
+% put |\relax| and not |\prg_do_nothing:|.
 %    \begin{macrocode}
-     \cs_set_eq:NN \NC@find@w \relax
-     \cs_set_eq:NN \NC@find@W \relax
+    \cs_set_eq:NN \NC@find@w \relax
+    \cs_set_eq:NN \NC@find@W \relax
 %    \end{macrocode}
 % 
 % We redefine the column types |w| and |W| of the package \pkg{array}.
 %    \begin{macrocode}
-     \newcolumntype{w}[2]
-       {>{\hbox_set:Nw \l_tmpa_box
-          \@@_Cell:}
-        c
-        <{\@@_end_Cell:
-          \hbox_set_end:
-          \makebox[##2][##1]{\box_use:N \l_tmpa_box}}}
-     \newcolumntype{W}[2]
-       {>{\hbox_set:Nw \l_tmpa_box
-          \@@_Cell:}
+    \newcolumntype w [ 2 ]
+      { 
+        > { 
+            \hbox_set:Nw \l_tmpa_box
+            \@@_Cell:}
         c
-        <{\@@_end_Cell:
-          \hbox_set_end:
-          \cs_set_eq:NN \hss \hfil
-          \makebox[##2][##1]{\box_use:N \l_tmpa_box}}}
+        < { 
+            \@@_end_Cell:
+            \hbox_set_end:
+            \makebox [ ##2 ] [ ##1 ] { \box_use:N \l_tmpa_box } 
+          } 
+      }
+    \newcolumntype W [ 2 ]
+      { 
+        > { 
+            \hbox_set:Nw \l_tmpa_box
+            \@@_Cell:
+          }
+       c
+       < { 
+           \@@_end_Cell:
+           \hbox_set_end:
+           \cs_set_eq:NN \hss \hfil
+           \makebox [ ##2 ] [ ##1 ] { \box_use:N \l_tmpa_box } 
+         } 
+      }
 %    \end{macrocode}
 % 
-% The commands |\Ldots|, |\Cdots|, etc. will be defined only in the environment |{NiceArray}|. If the class option
-% |draft| is used, these commands will be defined to be no-op (the dotted lines are not drawn).
+% The commands |\Ldots|, |\Cdots|, etc. will be defined only in the environment
+% |{NiceArray}|. If the class option |draft| is used, these commands will be
+% defined to be no-op (the dotted lines are not drawn). 
 %    \begin{macrocode}
-     \bool_if:NTF \c_@@_draft_bool
-            \@@_define_dots_to_nil:
-            \@@_define_dots:
-     \cs_set_eq:NN \Hspace \@@_Hspace:
-     \cs_set_eq:NN \Hdotsfor \@@_Hdotsfor
-     \cs_set_eq:NN \multicolumn \@@_multicolumn:nnn
+    \bool_if:NTF \c_@@_draft_bool
+      \@@_define_dots_to_nil:
+      \@@_define_dots:
+    \cs_set_eq:NN \Hspace \@@_Hspace:
+    \cs_set_eq:NN \Hdotsfor \@@_Hdotsfor
+    \cs_set_eq:NN \multicolumn \@@_multicolumn:nnn
 %    \end{macrocode}
 % 
 %
-% The sequence |\g_@@_empty_cells_seq| will contain a list of ``empty'' cells (not all the empty cells of the
-% matrix). If we want to indicate that the cell in row~$i$ and column~$j$ must be considered as empty, the token
-% list ``|i-j|'' will be put in this sequence.
+% The sequence |\g_@@_empty_cells_seq| will contain a list of ``empty'' cells
+% (not all the empty cells of the matrix). If we want to indicate that the cell
+% in row~$i$ and column~$j$ must be considered as empty, the token list
+% ``|i-j|'' will be put in this sequence. 
 %    \begin{macrocode}
-     \seq_gclear_new:N  \g_@@_empty_cells_seq
+    \seq_gclear_new:N  \g_@@_empty_cells_seq
 %    \end{macrocode}
 %
-% 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). 
+% 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_gclear_new:N \g_@@_multicolumn_cells_seq
-     \seq_gclear_new:N \g_@@_multicolumn_sizes_seq
+    \seq_gclear_new:N \g_@@_multicolumn_cells_seq
+    \seq_gclear_new:N \g_@@_multicolumn_sizes_seq
 %    \end{macrocode}
 % 
 %
-% The counter |\g_@@_row_int| will be used to count the rows of the array (its incrementation will be in
-% the first cell of the row). At the end of the environment |{array}|, this counter will give the total number of
-% rows of the matrix. 
+% The counter |\g_@@_row_int| will be used to count the rows of the array (its
+% incrementation will be in the first cell of the row). At the end of the
+% environment |{array}|, this counter will give the total number of rows of the
+% matrix.  
 %    \begin{macrocode}
-     \int_gzero_new:N \g_@@_row_int 
-     \int_gset:Nn \g_@@_row_int {\l_@@_nb_first_row_int - 1}
+    \int_gzero_new:N \g_@@_row_int 
+    \int_gset:Nn \g_@@_row_int { \l_@@_nb_first_row_int - 1 }
 %    \end{macrocode}
 %
-% The counter |\g_@@_column_int| will be used to count the columns of the array. Since we want to
-% know the total number of columns of the matrix, we also create a counter |\g_@@_column_total_int|.
-% These counters are updated in the command |\@@_Cell:| executed at the beginning of each cell. 
+% The counter |\g_@@_column_int| will be used to count the columns of the array.
+% Since we want to know the total number of columns of the matrix, we also
+% create a counter |\g_@@_column_total_int|. These counters are updated in the
+% command |\@@_Cell:| executed at the beginning of each cell.  
 %    \begin{macrocode}
-     \int_gzero_new:N \g_@@_column_int 
-     \int_gzero_new:N \g_@@_column_total_int
-     \cs_set_eq:NN \@ifnextchar \new@ifnextchar
+    \int_gzero_new:N \g_@@_column_int 
+    \int_gzero_new:N \g_@@_column_total_int
+    \cs_set_eq:NN \@ifnextchar \new@ifnextchar
 %    \end{macrocode}
 %
-% The extra horizontal spaces on both sides of an environment |{array}| should be considered as a bad idea of
-% standard LaTeX. In the environment |{matrix}| the package  \pkg{amsmath} prefers to suppress these spaces with
-% instructions ``|\hskip -\arraycolsep|''. In the same way, we decide to suppress them in |{NiceArray}|. However, for better
-% compatibility, we give an option |exterior-arraycolsep| to control this feature.
+% The extra horizontal spaces on both sides of an environment |{array}| should
+% be considered as a bad idea of standard LaTeX. In the environment |{matrix}|
+% the package  \pkg{amsmath} prefers to suppress these spaces with instructions
+% ``|\hskip -\arraycolsep|''. In the same way, we decide to suppress them in
+% |{NiceArray}|. However, for better compatibility, we give an option
+% |exterior-arraycolsep| to control this feature. 
 %    \begin{macrocode}
-     \bool_if:NF \l_@@_exterior_arraycolsep_bool
-         {\skip_horizontal:n {-\arraycolsep}}
+    \bool_if:NF \l_@@_exterior_arraycolsep_bool
+      { \skip_horizontal:n { - \arraycolsep } }
 %    \end{macrocode}
 % 
 %    \begin{macrocode}
-     \skip_horizontal:n {\l_@@_left_margin_dim + \l_@@_extra_left_margin_dim}
+    \skip_horizontal:n { \l_@@_left_margin_dim + \l_@@_extra_left_margin_dim }
 %    \end{macrocode}
 % 
 % 
-% Eventually, the environment |{NiceArray}| is defined upon the environment |{array}|. The token list |\l_@@_pos_tl|
-% will contain one of the values |t|, |c| or |b|.
+% Eventually, the environment |{NiceArray}| is defined upon the environment
+% |{array}|.  However, if the class used is \cls{revtex4-1} or \cls{revtex4-2},
+% we have to do some tuning and use the command |\@array@array| instead of
+% |\array| because these classes do a redefinition of |\array| incompatible with
+% our use of |\array|. 
 %    \begin{macrocode}
-     \array[\l_@@_pos_env_tl]{#2}}
+    \bool_if:NTF \c_@@_revtex_bool
+       { 
+         \cs_set_eq:NN \@acoll \@arrayacol 
+         \cs_set_eq:NN \@acolr \@arrayacol 
+         \cs_set_eq:NN \@acol \@arrayacol 
+         \cs_set:Npn \@halignto { }
+         \@array@array
+       }
+       \array
+%    \end{macrocode}
+% The token list |\l_@@_pos_env_str|, which is the argument of |\array| (or
+% |\@array@array|) will contain one of the values |t|, |c| or |b|. 
+%    \begin{macrocode}
+    [ \l_@@_pos_env_str ] { #2 } 
+  }
 %    \end{macrocode}
 %
 % \bigskip
 %    \begin{macrocode}
-    {\endarray
+  { \endarray
      \bool_if:NF \l_@@_exterior_arraycolsep_bool
-         {\skip_horizontal:n {-\arraycolsep}}
-     \skip_horizontal:n {\g_@@_right_margin_dim + \g_@@_extra_right_margin_dim}}
+       { \skip_horizontal:n { - \arraycolsep } }
+     \skip_horizontal:n 
+       { \g_@@_right_margin_dim + \g_@@_extra_right_margin_dim }
+  }
 %    \end{macrocode}
 %
 %
 % \interitem
 % We create the variants of the environment |{NiceMatrix}|.
 %    \begin{macrocode}
-\NewDocumentEnvironment {pNiceMatrix} {}
-   {\left(\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right)}
+\NewDocumentEnvironment { pNiceMatrix } { }
+   { \left( \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right) }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\NewDocumentEnvironment {bNiceMatrix} {}
-   {\left[\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right]}
+\NewDocumentEnvironment { bNiceMatrix } { }
+   { \left[ \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right] }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\NewDocumentEnvironment {BNiceMatrix} {}
-   {\left\{\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right\}}
+\NewDocumentEnvironment { BNiceMatrix } { }
+   { \left\{ \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right\} }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\NewDocumentEnvironment {vNiceMatrix} {}
-   {\left\lvert\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right\rvert}
+\NewDocumentEnvironment { vNiceMatrix } { }
+   { \left\lvert \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right\rvert }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\NewDocumentEnvironment {VNiceMatrix} {}
-   {\left\lVert\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right\rVert}
+\NewDocumentEnvironment { VNiceMatrix } {}
+   { \left\lVert \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right\rVert }
 %    \end{macrocode}
 %
 % \interitem
-% For the option \verb|columns-width=auto| (or the option |auto-columns-width| of the environment
-% |{NiceMatrixBlock}|), we want to know the maximal width of the cells of the array (except 
-% the cells of the ``exterior'' column of an environment of the kind of |{pNiceAccayC}|). This length can be known
-% only after the end of the construction of the array (or at the end of the environment |{NiceMatrixBlock}|).
-% That's why we store this value in the main |.aux| file and it will be available in the next run. We write a
-% dedicated command for this because it will be called in a~|\group_insert_after:N|.
+% For the option \verb|columns-width=auto| (or the option |auto-columns-width|
+% of the environment |{NiceMatrixBlock}|), we want to know the maximal width of
+% the cells of the array (except the cells of the ``exterior'' column of an
+% environment of the kind of |{pNiceAccayC}|). This length can be known only
+% after the end of the construction of the array (or at the end of the
+% environment |{NiceMatrixBlock}|). That's why we store this value in the main
+% |.aux| file and it will be available in the next run. We write a dedicated
+% command for this because it will be called in a~|\group_insert_after:N|. 
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_write_max_cell_width:
-    {\bool_if:NF \l_@@_block_auto_columns_width_bool
-       {\iow_now:Nn \@mainaux {\ExplSyntaxOn}
-        \iow_now:Nx \@mainaux {\cs_gset:cpn 
-                               {@@_max_cell_width_\int_use:N \g_@@_env_int}
-                               {\dim_use:N \g_@@_max_cell_width_dim} }
+  { 
+    \bool_if:NF \l_@@_block_auto_columns_width_bool
+      { 
+        \iow_now:Nn \@mainaux \ExplSyntaxOn 
+        \iow_now:Nx \@mainaux 
+          { 
+            \cs_gset:cpn { @@_max_cell_width_ \int_use:N \g_@@_env_int }
+              { \dim_use:N \g_@@_max_cell_width_dim } 
+          }
 %    \end{macrocode}
-% If the environment has a name, we also create an alias named |\@@_max_cell_width_|{\ttfamily\slshape name}.
+% If the environment has a name, we also create an alias named
+% |\@@_max_cell_width_|{\ttfamily\slshape name}.
 %    \begin{macrocode}
-          \iow_now:Nx \@mainaux {\cs_gset:cpn {@@_max_cell_width_\g_@@_name_tl} 
-                                              {\dim_use:N \g_@@_max_cell_width_dim} }
-        \iow_now:Nn \@mainaux {\ExplSyntaxOff}}}
+        \iow_now:Nx \@mainaux 
+          {
+            \cs_gset:cpn { @@_max_cell_width_ \g_@@_name_str } 
+              { \dim_use:N \g_@@_max_cell_width_dim } 
+          }
+        \iow_now:Nn \@mainaux \ExplSyntaxOff  
+      } 
+  }
 %    \end{macrocode}
 % 
 % \interitem
-% The conditionnal |\@@_if_not_empty_cell:nnT| tests wether a cell is empty. The first two arguments must be LaTeX3
-% counters for the row and the column of the considered cell.
+% The conditionnal |\@@_if_not_empty_cell:nnT| tests wether a cell is empty. The
+% first two arguments must be LaTeX3 counters for the row and the column of the
+% considered cell. 
 %    \begin{macrocode}
-\prg_set_conditional:Npnn \@@_if_not_empty_cell:nn #1#2 {T,TF}
+\prg_set_conditional:Npnn \@@_if_not_empty_cell:nn #1 #2 { T , TF }
 %    \end{macrocode}
-% If the cell is an implicit cell (that is after the symbol |\\| of end of row), the cell must, of course, be
-% considered as empty. It's easy to check wether we are in this situation considering the correspondant Tikz node.
+% If the cell is an implicit cell (that is after the symbol |\\| of end of row),
+% the cell must, of course, be considered as empty. It's easy to check wether we
+% are in this situation considering the correspondant Tikz node. 
 %    \begin{macrocode}
-       {\cs_if_exist:cTF {pgf@sh@ns@nm-\int_use:N \g_@@_env_int-
-                                       \int_use:N #1-
-                                       \int_use:N #2}
+  { 
+    \cs_if_free:cTF 
+      { pgf@sh@ns@nm -\int_use:N \g_@@_env_int - \int_use:N #1 - \int_use:N #2 }
+      \prg_return_false:
 %    \end{macrocode}
-% We manage a list of ``empty cells'' called |\g_@@_empty_cells_seq|. In fact, this list is not a list of all the
-% empty cells of the array but only those explicitely declared empty for some reason. It's easy to check if the
-% current cell is in this list.
+% We manage a list of ``empty cells'' called |\g_@@_empty_cells_seq|. In fact,
+% this list is not a list of all the empty cells of the array but only those
+% explicitely declared empty for some reason. It's easy to check if the current
+% cell is in this list. 
 %    \begin{macrocode}
-          {\seq_if_in:NxTF \g_@@_empty_cells_seq
-                           {\int_use:N #1-\int_use:N #2}
-             {\prg_return_false:}
+      { 
+        \seq_if_in:NxTF \g_@@_empty_cells_seq { \int_use:N #1 - \int_use:N #2 }
+          \prg_return_false:
 %    \end{macrocode}
-% In the general case, we consider the width of the Tikz node corresponding to the cell. In order to compute this
-% width, we have to extract the coordinate of the west and east anchors of the node. This extraction needs a
-% command environment |{pgfpicture}| but, in fact, nothing is drawn. 
+% In the general case, we consider the width of the Tikz node corresponding to
+% the cell. In order to compute this width, we have to extract the coordinate of
+% the west and east anchors of the node. This extraction needs a command
+% environment |{pgfpicture}| but, in fact, nothing is drawn.  
 %    \begin{macrocode}
-             {\begin{pgfpicture}
+          { 
+            \begin { pgfpicture }
 %    \end{macrocode}
 % We store the name of the node corresponding to the cell in |\l_tmpa_tl|.
 %    \begin{macrocode}
-                \tl_set:Nx \l_tmpa_tl {nm-\int_use:N \g_@@_env_int-
-                                          \int_use:N #1-
-                                          \int_use:N #2}
-                \pgfpointanchor \l_tmpa_tl {east}
-                \dim_gset:Nn \g_tmpa_dim \pgf@x
-                \pgfpointanchor \l_tmpa_tl {west}
-                \dim_gset:Nn \g_tmpb_dim \pgf@x
-              \end{pgfpicture}
-              \dim_compare:nNnTF {\dim_abs:n {\g_tmpb_dim-\g_tmpa_dim}} < {0.5 pt}
-                    \prg_return_false:
-                    \prg_return_true:
-             }}
-          \prg_return_false:
-       }
+            \tl_set:Nx \l_tmpa_tl 
+               { nm - \int_use:N \g_@@_env_int - \int_use:N #1 - \int_use:N #2 }
+            \pgfpointanchor \l_tmpa_tl { east }
+            \dim_gset:Nn \g_tmpa_dim \pgf@x
+            \pgfpointanchor \l_tmpa_tl { west }
+            \dim_gset:Nn \g_tmpb_dim \pgf@x
+            \end { pgfpicture } 
+            \dim_compare:nTF 
+              { \dim_abs:n { \g_tmpb_dim - \g_tmpa_dim } < 0.5 pt }
+              \prg_return_false:
+              \prg_return_true:
+          }
+      }
+  }
 %    \end{macrocode}
 %
 % \interitem
-% The argument of the following command |\@@_instruction_of_type:n| is the type of the instruction (|Cdots|,
-% |Vdots|, |Ddots|, etc.). This command writes in |\g_@@_lines_to_draw_tl| the instruction that will really draw
-% the line after the construction of the matrix.
+% The argument of the following command |\@@_instruction_of_type:n| is the type
+% of the instruction (|Cdots|, |Vdots|, |Ddots|, etc.). This command writes in
+% |\g_@@_lines_to_draw_tl| the instruction that will really draw the line after
+% the construction of the matrix. 
 %
 % \medskip
 % For example, for the following matrix,
@@ -2863,103 +3132,130 @@ version 2005/12/01 or later.
 % 
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_instruction_of_type:n 
-     {\tl_gput_right:Nx \g_@@_lines_to_draw_tl 
-           {\exp_not:c {@@_draw_#1:nn} 
-                       {\int_use:N \g_@@_row_int} 
-                       {\int_use:N \g_@@_column_int}}}
+  { 
+    \tl_gput_right:Nx \g_@@_lines_to_draw_tl 
+      { 
+        \exp_not:c { @@ _ draw _ #1 : nn } 
+          { \int_use:N \g_@@_row_int } 
+          { \int_use:N \g_@@_column_int }
+      }
+  }
 %    \end{macrocode}
 %
 % 
 % \subsection{After the construction of the array}
 %
-% First, we deactivate Tikz externalization (since we use Tikz pictures with the options |overlay| and 
-% |remember picture|, there would be errors).
+% First, we deactivate Tikz externalization (since we use Tikz pictures with the
+% options |overlay| and |remember picture|, there would be errors).
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_after_array:
-    {\group_begin:
-     \cs_if_exist:NT \tikz@library@external@loaded
-         {\tikzset{external/export = false}}
+  { 
+    \group_begin:
+    \cs_if_exist:NT \tikz@library@external@loaded
+      { \tikzset { external / export = false } } 
 %    \end{macrocode}
-% Now, the definition of the counters |\g_@@_column_int| and |\g_@@_column_total_int| change: |\g_@@_column_int|
-% will be the number of columns without the exterior column (in an environment like |{pNiceArrayC}|) and
-% |\g_@@_column_total_int| will be the number of columns with this exterior column.
+% Now, the definition of the counters |\g_@@_column_int| and
+% |\g_@@_column_total_int| change: |\g_@@_column_int| will be the number of
+% columns without the exterior column (in an environment like |{pNiceArrayC}|)
+% and |\g_@@_column_total_int| will be the number of columns with this exterior
+% column.  
 %    \begin{macrocode}
-     \int_gset_eq:NN \g_@@_column_int \g_@@_column_total_int
-     \bool_if:NT \l_@@_exterior_column_bool {\int_gdecr:N \g_@@_column_int} 
+    \int_gset_eq:NN \g_@@_column_int \g_@@_column_total_int
+    \bool_if:NT \l_@@_exterior_column_bool { \int_gdecr:N \g_@@_column_int }
 %    \end{macrocode}
 %
-% The sequence |\g_@@_yet_drawn_seq| contains a list of lines which have been drawn previously in the matrix. We
-% maintain this sequence because we don't want to draw two overlapping lines.
+% The sequence |\g_@@_yet_drawn_seq| contains a list of lines which have been
+% drawn previously in the matrix. We maintain this sequence because we don't
+% want to draw two overlapping lines. 
 %    \begin{macrocode}
-     \seq_gclear_new:N \g_@@_yet_drawn_seq
+    \seq_gclear_new:N \g_@@_yet_drawn_seq
 %    \end{macrocode}
 %
-% By default, the diagonal lines will be parallelized\footnote{It's possible to use the option
-% |parallelize-diags| to disable this parallelization.}. There are two types of diagonals lines: the $|\Ddots|$
-% diagonals and the |\Iddots| diagonals. We have to count both types in order to know wether a diagonal is the
-% first of its type in the current |{NiceArray}| environment.
+% By default, the diagonal lines will be parallelized\footnote{It's possible to
+% use the option |parallelize-diags| to disable this parallelization.}. There
+% are two types of diagonals lines: the $|\Ddots|$ diagonals and the |\Iddots|
+% diagonals. We have to count both types in order to know wether a diagonal is
+% the first of its type in the current |{NiceArray}| environment.
 %    \begin{macrocode}
-     \bool_if:NT \l_@@_parallelize_diags_bool
-          {\int_zero_new:N \l_@@_ddots_int
-           \int_zero_new:N \l_@@_iddots_int
-%    \end{macrocode}
-%
-% The dimensions |\l_@@_delta_x_one_dim| and |\l_@@_delta_y_one_dim| will contain the $\Delta_x$ and $\Delta_y$ of the
-% first |\Ddots| diagonal. We have to store these values in order to draw the others |\Ddots| diagonals parallel to
-% the first one. Similarly |\l_@@_delta_x_two_dim| and |\l_@@_delta_y_two_dim| are the $\Delta_x$ and $\Delta_y$ of
-% the first |\Iddots| diagonal.
-%    \begin{macrocode}
-           \dim_zero_new:N \l_@@_delta_x_one_dim
-           \dim_zero_new:N \l_@@_delta_y_one_dim
-           \dim_zero_new:N \l_@@_delta_x_two_dim
-           \dim_zero_new:N \l_@@_delta_y_two_dim}
+    \bool_if:NT \l_@@_parallelize_diags_bool
+      { 
+        \int_zero_new:N \l_@@_ddots_int
+        \int_zero_new:N \l_@@_iddots_int
+%    \end{macrocode}
+%
+% The dimensions |\l_@@_delta_x_one_dim| and |\l_@@_delta_y_one_dim| will
+% contain the $\Delta_x$ and $\Delta_y$ of the first |\Ddots| diagonal. We have
+% to store these values in order to draw the others |\Ddots| diagonals parallel
+% to the first one. Similarly |\l_@@_delta_x_two_dim| and
+% |\l_@@_delta_y_two_dim| are the $\Delta_x$ and $\Delta_y$ of the first
+% |\Iddots| diagonal. 
+%    \begin{macrocode}
+        \dim_zero_new:N \l_@@_delta_x_one_dim
+        \dim_zero_new:N \l_@@_delta_y_one_dim
+        \dim_zero_new:N \l_@@_delta_x_two_dim
+        \dim_zero_new:N \l_@@_delta_y_two_dim
+      }
 %    \end{macrocode}
 %
-% If the user has used the option |create-extra-nodes|, the ``medium nodes'' and ``large nodes'' are created. We
-% recall that the command |\@@_create_extra_nodes:|, when used once, becomes no-op (in the current TeX group).
+% If the user has used the option |create-extra-nodes|, the ``medium nodes'' and
+% ``large nodes'' are created. We recall that the command
+% |\@@_create_extra_nodes:|, when used once, becomes no-op (in the current TeX
+% group). 
 %    \begin{macrocode}
-     \bool_if:NT \g_@@_extra_nodes_bool \@@_create_extra_nodes:
+    \bool_if:NT \g_@@_extra_nodes_bool \@@_create_extra_nodes:
 %    \end{macrocode}
 % 
 % \bigskip
-% Now, we really draw the lines. The code to draw the lines has been constructed in the token list |\g_@@_lines_to_draw_tl|.
-%    \begin{macrocode}
-     \tl_if_empty:NF \g_@@_lines_to_draw_tl
-           {\int_zero_new:N  \l_@@_initial_i_int
-            \int_zero_new:N  \l_@@_initial_j_int
-            \int_zero_new:N  \l_@@_final_i_int
-            \int_zero_new:N  \l_@@_final_j_int
-            \@@_bool_new:N \l_@@_initial_open_bool
-            \@@_bool_new:N \l_@@_final_open_bool
-            \g_@@_lines_to_draw_tl}
-     \tl_gclear:N \g_@@_lines_to_draw_tl
+% Now, we really draw the lines. The code to draw the lines has been constructed
+% in the token list |\g_@@_lines_to_draw_tl|. 
+%    \begin{macrocode}
+    \tl_if_empty:NF \g_@@_lines_to_draw_tl
+      { 
+        \int_zero_new:N \l_@@_initial_i_int
+        \int_zero_new:N \l_@@_initial_j_int
+        \int_zero_new:N \l_@@_final_i_int
+        \int_zero_new:N \l_@@_final_j_int
+        \bool_set_false:N \l_@@_initial_open_bool
+        \bool_set_false:N \l_@@_final_open_bool
+        \g_@@_lines_to_draw_tl
+      }
+    \tl_gclear:N \g_@@_lines_to_draw_tl
 %    \end{macrocode}
 %
 % \bigskip
 % Now, the |code-after|.
 %    \begin{macrocode}
-     \tikzset{every~picture/.style = {overlay,
-                                      remember~picture,
-                                      name~prefix = nm-\int_use:N \g_@@_env_int-}}
-     \cs_set_eq:NN \line \@@_line:nn
-     \g_@@_code_after_tl 
-     \group_end:}
+    \tikzset 
+      { 
+        every~picture / .style = 
+         { 
+           overlay ,
+           remember~picture ,
+           name~prefix = nm - \int_use:N \g_@@_env_int - 
+         }
+      }
+    \cs_set_eq:NN \line \@@_line:nn
+    \g_@@_code_after_tl 
+    \group_end:
+  }
 %    \end{macrocode}
 %
 % \bigskip
-% A dotted line will be said \emph{open} in one of its extremities when it stops on the edge of the matrix and \emph{closed}
-% otherwise. In the following matrix, the dotted line is closed on its left extremity and open on its right.
+% A dotted line will be said \emph{open} in one of its extremities when it stops
+% on the edge of the matrix and \emph{closed} otherwise. In the following
+% matrix, the dotted line is closed on its left extremity and open on its right.
 % \[ \begin{pNiceMatrix}
 % a+b+c & a+b & a\\
 % a & \Cdots \\
 % a & a+b & a+b+c
 % \end{pNiceMatrix}\]
-% For a closed extremity, we use the normal node and for a open one, we use the ``medium node'' (the medium and
-% large nodes are created with |\@@_create_extra_nodes:| if they have not been created yet).
+% For a closed extremity, we use the normal node and for a open one, we use the
+% ``medium node'' (the medium and large nodes are created with
+% |\@@_create_extra_nodes:| if they have not been created yet).  
 % \[ \begin{pNiceMatrix}[create-extra-nodes,
 %                        code-after = {\begin{tikzpicture} 
 %                                      \node [highlight, fit={(2-1)}] {} ;
-%                                      \node [highlight, fit={(2-3-medium)}] {} ;
+%                                      \node [highlight, fit={(2-3-medium)}] {};
 %                                      \end{tikzpicture}
 %                                    }]
 % a+b+c & a+b & a\\
@@ -2973,321 +3269,434 @@ version 2005/12/01 or later.
 %
 % \begin{itemize}
 % \item the first argument is the row of the cell where the command was issued;
-% \item the second argument is the column of the cell where the command was issued;
-% \item the third argument is the $x$-value of the orientation vector of the line;
+% \item the second argument is the column of the cell where the command was
+% issued; 
+% \item the third argument is the $x$-value of the orientation vector of the
+% line; 
 % \item the fourth argument is the $y$-value the orientation vector of the line;
 % \end{itemize}
 %
 % This command computes:
 %
 % \begin{itemize}
-% \item |\l_@@_initial_i_int| and |\l_@@_initial_j_int| which are the coordinates of one extremity of the line;
-% \item |\l_@@_final_i_int| and |\l_@@_final_j_int| which are the coordinates of the other extremity of the line;
-% \item |\l_@@_initial_open_bool| and |\l_@@_final_open_bool| to indicate wether the extremities are open or not.
+% \item |\l_@@_initial_i_int| and |\l_@@_initial_j_int| which are the
+% coordinates of one extremity of the line; 
+% \item |\l_@@_final_i_int| and |\l_@@_final_j_int| which are the coordinates of
+% the other extremity of the line; 
+% \item |\l_@@_initial_open_bool| and |\l_@@_final_open_bool| to indicate wether
+% the extremities are open or not. 
 % \end{itemize}
 %
 %    \begin{macrocode}       
 \cs_new_protected:Nn \@@_find_extremities_of_line:nnnn
-          {\int_set:Nn \l_@@_initial_i_int {#1}
-           \int_set:Nn \l_@@_initial_j_int {#2}
-           \int_set:Nn \l_@@_final_i_int {#1}
-           \int_set:Nn \l_@@_final_j_int {#2}
-           \bool_set_false:N \l_@@_initial_open_bool
-           \bool_set_false:N \l_@@_final_open_bool
-%    \end{macrocode}
-% We will do two loops: one when determinating the initial cell and the other when determinating the final cell. 
-% The boolean |\l_@@_stop_loop_bool| will be used to control these loops.
-%    \begin{macrocode}
-           \@@_bool_new:N \l_@@_stop_loop_bool
-           \bool_do_until:Nn \l_@@_stop_loop_bool 
-              {\int_add:Nn \l_@@_final_i_int {#3}
-               \int_add:Nn \l_@@_final_j_int {#4}
+  { 
+    \int_set:Nn \l_@@_initial_i_int { #1 }
+    \int_set:Nn \l_@@_initial_j_int { #2 }
+    \int_set:Nn \l_@@_final_i_int { #1 }
+    \int_set:Nn \l_@@_final_j_int { #2 }
+    \bool_set_false:N \l_@@_initial_open_bool
+    \bool_set_false:N \l_@@_final_open_bool
+%    \end{macrocode}
+% We will do two loops: one when determinating the initial cell and the other
+% when determinating the final cell. The boolean |\l_@@_stop_loop_bool| will be
+% used to control these loops. 
+%    \begin{macrocode}
+    \bool_set_false:N \l_@@_stop_loop_bool
+    \bool_do_until:Nn \l_@@_stop_loop_bool 
+      { 
+        \int_add:Nn \l_@@_final_i_int { #3 }
+        \int_add:Nn \l_@@_final_j_int { #4 }
 %    \end{macrocode}
 % We test if we are still in the matrix. 
 %    \begin{macrocode}
-               \bool_if:nTF { \int_compare_p:nNn 
-                                  \l_@@_final_i_int < {\l_@@_nb_first_row_int - 1}
-                           || \int_compare_p:nNn 
-                                  \l_@@_final_i_int > \g_@@_row_int
-                           || \int_compare_p:nNn 
-                                  \l_@@_final_j_int < 1
-                           || \int_compare_p:nNn 
-                                  \l_@@_final_j_int > \g_@@_column_total_int
+        \bool_if:nTF 
+          {    
+               \int_compare_p:nNn
+                 \l_@@_final_i_int < { \l_@@_nb_first_row_int - 1 } 
+            || \int_compare_p:nNn \l_@@_final_i_int > \g_@@_row_int
+            || \int_compare_p:nNn \l_@@_final_j_int < \c_one_int
+            || \int_compare_p:nNn \l_@@_final_j_int > \g_@@_column_total_int
 %    \end{macrocode}
-% If you arrive in the column |C| of an environment with such columns (like |{pNiceArrayC}|), you must consider that
-% we are \emph{outside} the matrix except if we are drawing a vertical line (included in the column |C|).
+% If you arrive in the column |C| of an environment with such columns (like
+% |{pNiceArrayC}|), you must consider that we are \emph{outside} the matrix
+% except if we are drawing a vertical line (included in the column |C|). 
 %    \begin{macrocode}
-                           || \int_compare_p:nNn 
-                                  \l_@@_final_j_int > \g_@@_column_int    
-                              && \int_compare_p:nNn {#4} > 0 }
+            || \int_compare_p:nNn \l_@@_final_j_int > \g_@@_column_int    
+               && \int_compare_p:nNn { #4 } > \c_zero_int 
+          }
 %    \end{macrocode}
-% If we are outside the matrix, we have found the extremity of the dotted line and it's a \emph{open} extremity.
+% If we are outside the matrix, we have found the extremity of the dotted line
+% and it's a \emph{open} extremity. 
 %    \begin{macrocode}
-                       {\bool_set_true:N \l_@@_final_open_bool
+          { 
+            \bool_set_true:N \l_@@_final_open_bool
 %    \end{macrocode}
-% We do a step backwards because we will draw the dotted line upon the last cell in the matrix (we will use the
-% ``medium node'' of this cell).
+% We do a step backwards because we will draw the dotted line upon the last cell
+% in the matrix (we will use the ``medium node'' of this cell).
 %    \begin{macrocode}  
-                        \int_sub:Nn \l_@@_final_i_int {#3}
-                        \int_sub:Nn \l_@@_final_j_int {#4}
-                        \bool_set_true:N \l_@@_stop_loop_bool}
+            \int_sub:Nn \l_@@_final_i_int { #3 }
+            \int_sub:Nn \l_@@_final_j_int { #4 }
+            \bool_set_true:N \l_@@_stop_loop_bool
+          }
 %    \end{macrocode}
-% If we are in the matrix, we test if the cell is empty. If it's not the case, we stop the loop because we have
-% found the correct values for |\l_@@_final_i_int| and |\l_@@_final_j_int|.
+% If we are in the matrix, we test if the cell is empty. If it's not the case,
+% we stop the loop because we have found the correct values for
+% |\l_@@_final_i_int| and |\l_@@_final_j_int|. 
 %    \begin{macrocode}
-                       {\@@_if_not_empty_cell:nnT 
-                              \l_@@_final_i_int 
-                              \l_@@_final_j_int
-                              {\bool_set_true:N \l_@@_stop_loop_bool}}
-               }
+          { 
+            \@@_if_not_empty_cell:nnT \l_@@_final_i_int \l_@@_final_j_int
+              { \bool_set_true:N \l_@@_stop_loop_bool }
+          }
+      }
 %    \end{macrocode}
 % 
 % \interitem
-% For |\l_@@_initial_i_int| and |\l_@@_initial_j_int| the programmation is similar to the previous one.
-%    \begin{macrocode}
-           \bool_set_false:N \l_@@_stop_loop_bool
-           \bool_do_until:Nn \l_@@_stop_loop_bool 
-              {\int_sub:Nn \l_@@_initial_i_int {#3}
-               \int_sub:Nn \l_@@_initial_j_int {#4}
-               \bool_if:nTF 
-                       {   \int_compare_p:nNn 
-                               \l_@@_initial_i_int < \l_@@_nb_first_row_int
-                        || \int_compare_p:nNn 
-                               \l_@@_initial_i_int > \g_@@_row_int
-                        || \int_compare_p:nNn 
-                               \l_@@_initial_j_int < 1
-                        || \int_compare_p:nNn 
-                               \l_@@_initial_j_int > \g_@@_column_total_int}
-                       {\bool_set_true:N \l_@@_initial_open_bool
-                        \int_add:Nn \l_@@_initial_i_int {#3}
-                        \int_add:Nn \l_@@_initial_j_int {#4}
-                        \bool_set_true:N \l_@@_stop_loop_bool}
-                       {\@@_if_not_empty_cell:nnT 
-                              \l_@@_initial_i_int 
-                              \l_@@_initial_j_int
-                              {\bool_set_true:N \l_@@_stop_loop_bool}}
-               }
+% For |\l_@@_initial_i_int| and |\l_@@_initial_j_int| the programmation is
+% similar to the previous one.
+%    \begin{macrocode}
+    \bool_set_false:N \l_@@_stop_loop_bool
+    \bool_do_until:Nn \l_@@_stop_loop_bool 
+      { 
+        \int_sub:Nn \l_@@_initial_i_int { #3 }
+        \int_sub:Nn \l_@@_initial_j_int { #4 }
+        \bool_if:nTF 
+          { 
+            \int_compare_p:nNn \l_@@_initial_i_int < \l_@@_nb_first_row_int
+              || 
+            \int_compare_p:nNn \l_@@_initial_i_int > \g_@@_row_int
+              || 
+            \int_compare_p:nNn \l_@@_initial_j_int < 1
+              || 
+            \int_compare_p:nNn \l_@@_initial_j_int > \g_@@_column_total_int
+          }
+          { 
+            \bool_set_true:N \l_@@_initial_open_bool
+            \int_add:Nn \l_@@_initial_i_int { #3 }
+            \int_add:Nn \l_@@_initial_j_int { #4 }
+            \bool_set_true:N \l_@@_stop_loop_bool
+          }
+          { 
+            \@@_if_not_empty_cell:nnT 
+              \l_@@_initial_i_int \l_@@_initial_j_int
+              { \bool_set_true:N \l_@@_stop_loop_bool }
+          }
+      }
 %    \end{macrocode}
-% If we have at least one open extremity, we create the ``medium nodes'' in the matrix (in the case of an open
-% extremity, the dotted line uses the ``medium node'' of the last empty cell). We remind that, when used once, the
-% command |\@@_create_extra_nodes:| becomes no-op in the current TeX group.
+% If we have at least one open extremity, we create the ``medium nodes'' in the
+% matrix (in the case of an open extremity, the dotted line uses the ``medium
+% node'' of the last empty cell). We remind that, when used once, the command
+% |\@@_create_extra_nodes:| becomes no-op in the current TeX group. 
 %    \begin{macrocode}
-           \bool_if:nT {\l_@@_initial_open_bool || \l_@@_final_open_bool}
-                       \@@_create_extra_nodes: }
+    \bool_if:nT { \l_@@_initial_open_bool || \l_@@_final_open_bool }
+      \@@_create_extra_nodes: 
+  }
 %    \end{macrocode}
 %
 % \interitem
-% If the dotted line to draw is in the list of the previously drawn lines (|\g_@@_yet_drawn_seq|), we don't draw
-% (so, we won't have overlapping lines in the \textsc{pdf}). The token list |\l_tmpa_tl| is the $4$-uplet
-% characteristic of the line.
-%    \begin{macrocode}
-\prg_set_conditional:Npnn \@@_if_yet_drawn: {F}
-            {\tl_set:Nx \l_tmpa_tl {\int_use:N \l_@@_initial_i_int-
-                                    \int_use:N \l_@@_initial_j_int-
-                                    \int_use:N \l_@@_final_i_int-
-                                    \int_use:N \l_@@_final_j_int}
-             \seq_if_in:NVTF \g_@@_yet_drawn_seq \l_tmpa_tl
+% If the dotted line to draw is in the list of the previously drawn lines
+% (|\g_@@_yet_drawn_seq|), we don't draw (so, we won't have overlapping lines in
+% the \textsc{pdf}). The token list |\l_tmpa_tl| is the $4$-uplet characteristic
+% of the line. 
+%    \begin{macrocode}
+\prg_set_conditional:Npnn \@@_if_yet_drawn: { F }
+  { 
+    \tl_set:Nx \l_tmpa_tl 
+      { 
+        \int_use:N \l_@@_initial_i_int -
+        \int_use:N \l_@@_initial_j_int -
+        \int_use:N \l_@@_final_i_int -
+        \int_use:N \l_@@_final_j_int
+      }
+    \seq_if_in:NVTF \g_@@_yet_drawn_seq \l_tmpa_tl
 %    \end{macrocode}
 %
-% If the dotted line to draw is not in the list, we add it to the list |\g_@@_yet_drawn_seq|.
+% If the dotted line to draw is not in the list, we add it to the list
+% |\g_@@_yet_drawn_seq|. 
 %    \begin{macrocode}
-              {\prg_return_true:}
-              {\seq_gput_left:NV \g_@@_yet_drawn_seq \l_tmpa_tl
-               \prg_return_false:}}
+      \prg_return_true:
+      {
+        \seq_gput_left:NV \g_@@_yet_drawn_seq \l_tmpa_tl
+        \prg_return_false:
+      }
+  }
 %    \end{macrocode}
 %
 %
 % \interitem 
-% The command |\@@_retrieve_coords:nn| retrieves the Tikz coordinates of the two extremities of the dotted line we
-% will have to draw \footnote{In fact, with diagonal lines, or vertical lines in columns of type |L| or |R|, an
-% adjustment of one of the coordinates may be done.}. This command has four implicit arguments which are
-% |\l_@@_initial_i_int|, |\l_@@_initial_j_int|, |\l_@@_final_i_int| and |\l_@@_final_j_int|.
+% The command |\@@_retrieve_coords:nn| retrieves the Tikz coordinates of the two
+% extremities of the dotted line we will have to draw \footnote{In fact, with
+% diagonal lines, or vertical lines in columns of type |L| or |R|, an adjustment
+% of one of the coordinates may be done.}. This command has four implicit
+% arguments which are |\l_@@_initial_i_int|, |\l_@@_initial_j_int|,
+% |\l_@@_final_i_int| and |\l_@@_final_j_int|. 
 %
-% The two arguments of the command |\@@_retrieve_coords:nn| are the prefix and the anchor that must be used for the
-% two nodes. 
+% The two arguments of the command |\@@_retrieve_coords:nn| are the prefix and
+% the anchor that must be used for the two nodes. 
 %
-% The coordinates are stored in |\g_@@_x_initial_dim|, |\g_@@_y_initial_dim|, |\g_@@_x_final_dim|,
-% |\g_@@_y_final_dim|. These variables are global for technical reasons: we have to do an affectation in an
-% environment |{tikzpicture}|.
+% The coordinates are stored in |\g_@@_x_initial_dim|, |\g_@@_y_initial_dim|,
+% |\g_@@_x_final_dim|, |\g_@@_y_final_dim|. These variables are global for
+% technical reasons: we have to do an affectation in an environment
+% |{tikzpicture}|. 
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_retrieve_coords:nn
-     {\dim_gzero_new:N \g_@@_x_initial_dim 
-      \dim_gzero_new:N \g_@@_y_initial_dim 
-      \dim_gzero_new:N \g_@@_x_final_dim 
-      \dim_gzero_new:N \g_@@_y_final_dim
-      \begin{tikzpicture}[remember~picture]
+  { 
+    \dim_gzero_new:N \g_@@_x_initial_dim 
+    \dim_gzero_new:N \g_@@_y_initial_dim 
+    \dim_gzero_new:N \g_@@_x_final_dim 
+    \dim_gzero_new:N \g_@@_y_final_dim
+    \begin { tikzpicture } [ remember~picture ]
       \tikz@parse@node\pgfutil@firstofone
-             (nm-\int_use:N \g_@@_env_int-
-                 \int_use:N \l_@@_initial_i_int-
-                 \int_use:N \l_@@_initial_j_int #1)
+        ( nm - \int_use:N \g_@@_env_int -
+               \int_use:N \l_@@_initial_i_int -
+               \int_use:N \l_@@_initial_j_int #1 )
       \dim_gset:Nn \g_@@_x_initial_dim \pgf@x
       \dim_gset:Nn \g_@@_y_initial_dim \pgf@y
       \tikz@parse@node\pgfutil@firstofone
-             (nm-\int_use:N \g_@@_env_int-
-                 \int_use:N \l_@@_final_i_int-
-                 \int_use:N \l_@@_final_j_int #2)
+        ( nm - \int_use:N \g_@@_env_int -
+               \int_use:N \l_@@_final_i_int -
+               \int_use:N \l_@@_final_j_int #2 )
       \dim_gset:Nn \g_@@_x_final_dim \pgf@x
       \dim_gset:Nn \g_@@_y_final_dim \pgf@y
-      \end{tikzpicture} }
-\cs_generate_variant:Nn \@@_retrieve_coords:nn {xx}
+    \end { tikzpicture } 
+  }
+\cs_generate_variant:Nn \@@_retrieve_coords:nn { x x }
 %    \end{macrocode}
 %
 % \interitem
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_draw_Ldots:nn
-      {\@@_find_extremities_of_line:nnnn {#1} {#2} 0 1 
-       \@@_if_yet_drawn:F \@@_actually_draw_Ldots:}
+  { 
+    \@@_find_extremities_of_line:nnnn { #1 } { #2 } \c_zero_int \c_one_int 
+    \@@_if_yet_drawn:F \@@_actually_draw_Ldots:
+  }
 %    \end{macrocode}
 % 
 % \medskip
-% The command |\@@_actually_draw_Ldots:| actually draws the |Ldots| line using |\l_@@_initial_i_int|,
-% |\l_@@_initial_j_int|, |\l_@@_initial_open_bool|, |\l_@@_final_i_int|, |\l_@@_final_j_int| and
-% |\l_@@_final_open_bool|. We have a dedicated command because if is used also by |\Hdotsfor|.
+% The command |\@@_actually_draw_Ldots:| actually draws the |Ldots| line using
+% |\l_@@_initial_i_int|, |\l_@@_initial_j_int|, |\l_@@_initial_open_bool|,
+% |\l_@@_final_i_int|, |\l_@@_final_j_int| and |\l_@@_final_open_bool|. We have
+% a dedicated command because if is used also by |\Hdotsfor|. 
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_actually_draw_Ldots:
-          {\@@_retrieve_coords:xx {\bool_if:NTF \l_@@_initial_open_bool
-                                     {-medium.base~west}
-                                     {.base~east}} 
-                                  {\bool_if:NTF \l_@@_final_open_bool 
-                                     {-medium.base~east}
-                                     {.base~west}}
-           \bool_if:NT \l_@@_initial_open_bool
-                 {\dim_gset_eq:NN \g_@@_y_initial_dim \g_@@_y_final_dim }
-           \bool_if:NT \l_@@_final_open_bool                 
-                 {\dim_gset_eq:NN \g_@@_y_final_dim \g_@@_y_initial_dim }
+  { 
+    \@@_retrieve_coords:xx 
+      { 
+        \bool_if:NTF \l_@@_initial_open_bool
+          { - medium.base~west }
+          { .base~east } 
+      } 
+      {  
+        \bool_if:NTF \l_@@_final_open_bool 
+          { - medium.base~east }
+          { . base~west }
+      }
+    \bool_if:NT \l_@@_initial_open_bool
+      { \dim_gset_eq:NN \g_@@_y_initial_dim \g_@@_y_final_dim }
+    \bool_if:NT \l_@@_final_open_bool                 
+      { \dim_gset_eq:NN \g_@@_y_final_dim \g_@@_y_initial_dim }
 %    \end{macrocode}
-% We raise the line of a quantity equal to the radius of the dots because we want the dots really ``on'' the line
-% of texte.
+% We raise the line of a quantity equal to the radius of the dots because we
+% want the dots really ``on'' the line of texte.
 %    \begin{macrocode}
-           \dim_gadd:Nn \g_@@_y_initial_dim {0.53pt}
-           \dim_gadd:Nn \g_@@_y_final_dim {0.53pt}
-           \@@_draw_tikz_line:}
+    \dim_gadd:Nn \g_@@_y_initial_dim { 0.53 pt }
+    \dim_gadd:Nn \g_@@_y_final_dim { 0.53 pt }
+    \@@_draw_tikz_line:
+  }
 %    \end{macrocode}
 %
 % \bigskip
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_draw_Cdots:nn
-      {\@@_find_extremities_of_line:nnnn {#1} {#2} 0 1 
-       \@@_if_yet_drawn:F
-            {\@@_retrieve_coords:xx {\bool_if:NTF \l_@@_initial_open_bool
-                                        {-medium.mid~west}
-                                        {.mid~east}} 
-                                    {\bool_if:NTF \l_@@_final_open_bool
-                                        {-medium.mid~east}
-                                        {.mid~west}}
-             \bool_if:NT \l_@@_initial_open_bool
-                   {\dim_gset_eq:NN \g_@@_y_initial_dim \g_@@_y_final_dim }
-             \bool_if:NT \l_@@_final_open_bool                 
-                   {\dim_gset_eq:NN \g_@@_y_final_dim \g_@@_y_initial_dim }
-             \@@_draw_tikz_line:}}
+  { 
+    \@@_find_extremities_of_line:nnnn { #1 } { #2 } \c_zero_int \c_one_int 
+    \@@_if_yet_drawn:F
+      { 
+        \@@_retrieve_coords:xx 
+          { 
+            \bool_if:NTF \l_@@_initial_open_bool
+              { - medium.mid~west }
+              { .mid~east }
+          } 
+          { 
+            \bool_if:NTF \l_@@_final_open_bool
+            { - medium.mid~east }
+            { .mid~west }
+          }
+        \bool_if:NT \l_@@_initial_open_bool
+          { \dim_gset_eq:NN \g_@@_y_initial_dim \g_@@_y_final_dim }
+        \bool_if:NT \l_@@_final_open_bool                 
+          { \dim_gset_eq:NN \g_@@_y_final_dim \g_@@_y_initial_dim }
+        \@@_draw_tikz_line:
+      }
+  }
 %    \end{macrocode}
 %
 % \bigskip
-% For the vertical dots, we have to distinguish different instances because we want really vertical lines. Be
-% careful: it's not possible to insert the command |\@@_retrieve_coords:nn| in the arguments |T| and |F| of the
-% \pkg{expl3} commands (why?).
+% For the vertical dots, we have to distinguish different instances because we
+% want really vertical lines. Be careful: it's not possible to insert the
+% command |\@@_retrieve_coords:nn| in the arguments |T| and |F| of the
+% \pkg{expl3} commands (why?). 
 %    \begin{macrocode}      
 \cs_new_protected:Nn \@@_draw_Vdots:nn
-      {\@@_find_extremities_of_line:nnnn {#1} {#2} 1 0
-       \@@_if_yet_drawn:F
-       {\@@_retrieve_coords:xx {\bool_if:NTF \l_@@_initial_open_bool
-                                  {-medium.north~west}
-                                  {.south~west}} 
-                               {\bool_if:NTF \l_@@_final_open_bool
-                                   {-medium.south~west}
-                                   {.north~west}}
-%    \end{macrocode}
-% The boolean |\l_tmpa_bool| indicates wether the column is of type |l| (|L| of |{NiceArray}|) or may be considered
-% as if.
+  { 
+    \@@_find_extremities_of_line:nnnn { #1 } { #2 } \c_one_int \c_zero_int
+    \@@_if_yet_drawn:F
+      { \@@_retrieve_coords:xx 
+          { 
+            \bool_if:NTF \l_@@_initial_open_bool
+              { - medium.north~west }
+              { .south~west }
+          } 
+          { 
+            \bool_if:NTF \l_@@_final_open_bool
+              { - medium.south~west }
+              { .north~west }
+          }
+%    \end{macrocode}
+% The boolean |\l_tmpa_bool| indicates wether the column is of type |l| (|L| of
+% |{NiceArray}|) or may be considered as if.
 %    \begin{macrocode}      
-       \bool_set:Nn \l_tmpa_bool 
-                    {\dim_compare_p:nNn \g_@@_x_initial_dim = \g_@@_x_final_dim}
-       \@@_retrieve_coords:xx {\bool_if:NTF \l_@@_initial_open_bool
-                                 {-medium.north}
-                                 {.south}} 
-                              {\bool_if:NTF \l_@@_final_open_bool  
-                                 {-medium.south}
-                                 {.north}}
-%    \end{macrocode}
-% The boolean |\l_tmpb_bool| indicates wether the column is of type |c| (|C| of |{NiceArray}|) or may be considered
-% as if.
+        \bool_set:Nn \l_tmpa_bool 
+          { \dim_compare_p:nNn \g_@@_x_initial_dim = \g_@@_x_final_dim }
+        \@@_retrieve_coords:xx 
+          { 
+            \bool_if:NTF \l_@@_initial_open_bool
+              { - medium.north }
+              { .south }
+          } 
+          { 
+            \bool_if:NTF \l_@@_final_open_bool  
+              { - medium.south }
+              { .north }
+          }
+%    \end{macrocode}
+% The boolean |\l_tmpb_bool| indicates wether the column is of type |c| (|C| of
+% |{NiceArray}|) or may be considered as if.
 %    \begin{macrocode}      
-       \bool_set:Nn \l_tmpb_bool 
-                    {\dim_compare_p:nNn \g_@@_x_initial_dim = \g_@@_x_final_dim}
-       \bool_if:NF \l_tmpb_bool
-            {\dim_gset:Nn \g_@@_x_initial_dim
-                         {\bool_if:NTF \l_tmpa_bool \dim_min:nn \dim_max:nn
-                                       \g_@@_x_initial_dim \g_@@_x_final_dim}
-             \dim_gset_eq:NN \g_@@_x_final_dim \g_@@_x_initial_dim}
-       \@@_draw_tikz_line:}}
+        \bool_set:Nn \l_tmpb_bool 
+          { \dim_compare_p:nNn \g_@@_x_initial_dim = \g_@@_x_final_dim }
+        \bool_if:NF \l_tmpb_bool
+          { 
+            \dim_gset:Nn \g_@@_x_initial_dim
+              { 
+                \bool_if:NTF \l_tmpa_bool \dim_min:nn \dim_max:nn
+                  \g_@@_x_initial_dim \g_@@_x_final_dim
+              }
+            \dim_gset_eq:NN \g_@@_x_final_dim \g_@@_x_initial_dim
+          }
+        \@@_draw_tikz_line:
+      }
+  }
 %    \end{macrocode}
 %
 % \interitem
-% For the diagonal lines, the situation is a bit more complicated because, by default, we parallelize the diagonals
-% lines. The first diagonal line is drawn and then, all the other diagonal lines are drawn parallel to the first
-% one.
+% For the diagonal lines, the situation is a bit more complicated because, by
+% default, we parallelize the diagonals lines. The first diagonal line is drawn
+% and then, all the other diagonal lines are drawn parallel to the first one.
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_draw_Ddots:nn
-   {\@@_find_extremities_of_line:nnnn {#1} {#2} 1 1 
+  { 
+    \@@_find_extremities_of_line:nnnn { #1 } { #2 } \c_one_int \c_one_int
     \@@_if_yet_drawn:F
-    {\@@_retrieve_coords:xx {\bool_if:NTF \l_@@_initial_open_bool
-                                 {-medium.north~west}
-                                 {.south~east}} 
-                            {\bool_if:NTF \l_@@_final_open_bool
-                                 {-medium.south~east}
-                                 {.north~west}}
+      { 
+        \@@_retrieve_coords:xx 
+          { 
+            \bool_if:NTF \l_@@_initial_open_bool
+              { - medium.north~west }
+              { .south~east }
+          } 
+          { 
+            \bool_if:NTF \l_@@_final_open_bool
+              { - medium.south~east }
+              { .north~west }
+          }
 %    \end{macrocode}
-% We have retrieved the coordinates in the usual way (they are stored in |\g_@@_x_initial_dim|, etc.).
-% If the parallelization of the diagonals is set, we will have (maybe) to adjust the fourth coordinate.
+% We have retrieved the coordinates in the usual way (they are stored in
+% |\g_@@_x_initial_dim|, etc.). If the parallelization of the diagonals is set,
+% we will have (maybe) to adjust the fourth coordinate. 
 %    \begin{macrocode}
-    \bool_if:NT \l_@@_parallelize_diags_bool
-       {\int_incr:N \l_@@_ddots_int
+        \bool_if:NT \l_@@_parallelize_diags_bool
+          { 
+            \int_incr:N \l_@@_ddots_int
 %    \end{macrocode}
-% We test if the diagonal line is the first one (the counter |\l_@@_ddots_int| is created for this usage).
+% We test if the diagonal line is the first one (the counter |\l_@@_ddots_int|
+% is created for this usage). 
 %    \begin{macrocode}
-        \int_compare:nNnTF \l_@@_ddots_int = 1
+            \int_compare:nNnTF \l_@@_ddots_int = \c_one_int
 %    \end{macrocode}
-% If the diagonal line is the first one, we have no adjustment of the line to do but we store the $\Delta_x$ and the
-% $\Delta_y$ of the line because these values will be used to draw the others diagonal lines parallels to the first one.
+% If the diagonal line is the first one, we have no adjustment of the line to do
+% but we store the $\Delta_x$ and the $\Delta_y$ of the line because these
+% values will be used to draw the others diagonal lines parallels to the first
+% one. 
 %    \begin{macrocode}
-          {\dim_set:Nn \l_@@_delta_x_one_dim {\g_@@_x_final_dim - \g_@@_x_initial_dim }
-           \dim_set:Nn \l_@@_delta_y_one_dim {\g_@@_y_final_dim - \g_@@_y_initial_dim }}
+              { 
+                \dim_set:Nn \l_@@_delta_x_one_dim 
+                  { \g_@@_x_final_dim - \g_@@_x_initial_dim }
+                \dim_set:Nn \l_@@_delta_y_one_dim 
+                  { \g_@@_y_final_dim - \g_@@_y_initial_dim }
+              }
 %    \end{macrocode}
-% If the diagonal line is not the first one, we have to adjust the second extremity of the line by modifying 
-% the coordinate |\g_@@_y_initial_dim|.
+% If the diagonal line is not the first one, we have to adjust the second
+% extremity of the line by modifying the coordinate |\g_@@_y_initial_dim|.
 %    \begin{macrocode}
-          {\dim_gset:Nn \g_@@_y_final_dim          
-                  {\g_@@_y_initial_dim +
-                      (\g_@@_x_final_dim - \g_@@_x_initial_dim)
-                      * \dim_ratio:nn \l_@@_delta_y_one_dim \l_@@_delta_x_one_dim }}}
+              { 
+                \dim_gset:Nn \g_@@_y_final_dim          
+                  { 
+                    \g_@@_y_initial_dim +
+                    ( \g_@@_x_final_dim - \g_@@_x_initial_dim ) * 
+                    \dim_ratio:nn \l_@@_delta_y_one_dim \l_@@_delta_x_one_dim 
+                  }
+              }
+          }
 %    \end{macrocode}
-% Now, we can draw the dotted line (after a possible change of |\g_@@_y_initial_dim|).
+% Now, we can draw the dotted line (after a possible change of
+% |\g_@@_y_initial_dim|). 
 %    \begin{macrocode}
-    \@@_draw_tikz_line:}}
+        \@@_draw_tikz_line:
+      }
+  }
 %    \end{macrocode}
 %
 % \bigskip
 % We draw the |\Iddots| diagonals in the same way.
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_draw_Iddots:nn
-   {\@@_find_extremities_of_line:nnnn {#1} {#2} 1 {-1}
+  {
+    \@@_find_extremities_of_line:nnnn { #1 } { #2 } 1 { -1 }
     \@@_if_yet_drawn:F
-    {\@@_retrieve_coords:xx {\bool_if:NTF \l_@@_initial_open_bool
-                              {-medium.north~east}
-                              {.south~west}} 
-                           {\bool_if:NTF \l_@@_final_open_bool
-                              {-medium.south~west}
-                              {.north~east}}
-     \bool_if:NT \l_@@_parallelize_diags_bool
-        {\int_incr:N \l_@@_iddots_int
-         \int_compare:nNnTF \l_@@_iddots_int = 1
-           {\dim_set:Nn \l_@@_delta_x_two_dim {\g_@@_x_final_dim - \g_@@_x_initial_dim}
-            \dim_set:Nn \l_@@_delta_y_two_dim {\g_@@_y_final_dim - \g_@@_y_initial_dim}}
-           {\dim_gset:Nn \g_@@_y_final_dim
-                   {\g_@@_y_initial_dim +
-                       (\g_@@_x_final_dim - \g_@@_x_initial_dim)
-                       * \dim_ratio:nn \l_@@_delta_y_two_dim \l_@@_delta_x_two_dim }}}
-    \@@_draw_tikz_line:}}
+      { \@@_retrieve_coords:xx 
+          { 
+            \bool_if:NTF \l_@@_initial_open_bool
+              { - medium.north~east }
+              { .south~west }
+          } 
+          { 
+            \bool_if:NTF \l_@@_final_open_bool
+              { - medium.south~west }
+              { .north~east }
+          }
+        \bool_if:NT \l_@@_parallelize_diags_bool
+          { 
+            \int_incr:N \l_@@_iddots_int
+            \int_compare:nNnTF \l_@@_iddots_int = \c_one_int
+              { 
+                \dim_set:Nn \l_@@_delta_x_two_dim 
+                  { \g_@@_x_final_dim - \g_@@_x_initial_dim }
+                \dim_set:Nn \l_@@_delta_y_two_dim 
+                  { \g_@@_y_final_dim - \g_@@_y_initial_dim }
+              }
+              { 
+                \dim_gset:Nn \g_@@_y_final_dim
+                   { 
+                     \g_@@_y_initial_dim +
+                     ( \g_@@_x_final_dim - \g_@@_x_initial_dim ) *
+                     \dim_ratio:nn \l_@@_delta_y_two_dim \l_@@_delta_x_two_dim 
+                   }
+              }
+          }
+        \@@_draw_tikz_line:
+      }
+  }
 %    \end{macrocode}
 %
 % \bigskip
@@ -3300,92 +3709,131 @@ version 2005/12/01 or later.
 %
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_draw_tikz_line:
-                 { 
+  { 
+%    \end{macrocode}
+% The dimension |\l_@@_l_dim| is the length $\ell$ of the line to draw. We use
+% the floating point reals of \pkg{expl3} to compute this length.
+%    \begin{macrocode}
+    \dim_zero_new:N \l_@@_l_dim
+    \dim_set:Nn \l_@@_l_dim
+      { 
+        \fp_to_dim:n 
+          { 
+            sqrt 
+             ( (   \dim_use:N \g_@@_x_final_dim 
+                 - \dim_use:N \g_@@_x_initial_dim 
+               ) ^ 2
+                  +
+               (   \dim_use:N \g_@@_y_final_dim 
+                 - \dim_use:N \g_@@_y_initial_dim
+               ) ^ 2 
+             )
+          }
+      }
 %    \end{macrocode}
-% The dimension |\l_@@_l_dim| is the length $\ell$ of the line to draw. We use the floating point reals of
-% \pkg{expl3} to compute this length.
+% We draw only if the length is not equel to zero (in fact, in the first
+% compilation, the length may be equal to zero). 
 %    \begin{macrocode}
-                   \dim_zero_new:N \l_@@_l_dim
-                   \dim_set:Nn \l_@@_l_dim
-                              { \fp_to_dim:n 
-                                  { sqrt( (  \dim_use:N \g_@@_x_final_dim 
-                                            -\dim_use:N \g_@@_x_initial_dim) ^2
-                                         +(  \dim_use:N \g_@@_y_final_dim 
-                                            -\dim_use:N \g_@@_y_initial_dim) ^2 )}
-                              }
+    \dim_compare:nNnF \l_@@_l_dim = \c_zero_dim
 %    \end{macrocode}
-% We draw only if the length is not equel to zero (in fact, in the first compilation, the length may be equal to
-% zero). 
+% The integer |\l_tmpa_int| is the number of dots of the dotted line.
 %    \begin{macrocode}
-                   \dim_compare:nNnF \l_@@_l_dim = \c_zero_dim
+      { 
+        \bool_if:NTF \l_@@_initial_open_bool
+          { 
+            \bool_if:NTF \l_@@_final_open_bool
+              { 
+                \int_set:Nn \l_tmpa_int 
+                  { \dim_ratio:nn \l_@@_l_dim { 0.45 em } }
+              }
+              { 
+                \int_set:Nn \l_tmpa_int 
+                  { \dim_ratio:nn { \l_@@_l_dim - 0.3 em } { 0.45 em } }
+              }
+          }
+          { 
+            \bool_if:NTF \l_@@_final_open_bool
+              { 
+                \int_set:Nn \l_tmpa_int 
+                  { \dim_ratio:nn { \l_@@_l_dim - 0.3 em } { 0.45 em } }
+              }
+              { \int_set:Nn \l_tmpa_int 
+                  { \dim_ratio:nn { \l_@@_l_dim - 0.6 em } { 0.45 em }}
+              }
+          }
 %    \end{macrocode}
-% The integer |\l_tmpa_int| is the number of dots of the dotted line.
+% The dimensions |\l_tmpa_dim| and |\l_tmpb_dim| are the coordinates of the
+% vector between two dots in the dotted line.
 %    \begin{macrocode}
-                     {\bool_if:NTF \l_@@_initial_open_bool
-                       {\bool_if:NTF \l_@@_final_open_bool
-                           {\int_set:Nn \l_tmpa_int 
-                                        {\dim_ratio:nn {\l_@@_l_dim} {0.45em}}}
-                           {\int_set:Nn \l_tmpa_int 
-                                        {\dim_ratio:nn {\l_@@_l_dim - 0.3em} {0.45em}}}}
-                       {\bool_if:NTF \l_@@_final_open_bool
-                           {\int_set:Nn \l_tmpa_int 
-                                        {\dim_ratio:nn {\l_@@_l_dim - 0.3em} {0.45em}}}
-                           {\int_set:Nn \l_tmpa_int 
-                                        {\dim_ratio:nn {\l_@@_l_dim - 0.6em} {0.45em}}}}
-%    \end{macrocode}
-% The dimensions |\l_tmpa_dim| and |\l_tmpb_dim| are the coordinates of the vector between two dots in the
-% dotted line.
-%    \begin{macrocode}
-                      \dim_set:Nn \l_tmpa_dim {(\g_@@_x_final_dim - \g_@@_x_initial_dim)
-                                                 * \dim_ratio:nn {0.45em} \l_@@_l_dim}
-                      \dim_set:Nn \l_tmpb_dim {(\g_@@_y_final_dim - \g_@@_y_initial_dim)
-                                                 * \dim_ratio:nn {0.45em} \l_@@_l_dim}
-%    \end{macrocode}
-%
-% The length $\ell$ is the length of the dotted line. We note $\Delta$ the length between two dots and $n$ the
-% number of intervals between dots. We note $\delta = \frac12(\ell - n \Delta)$.
-% The distance between the initial extremity of the line and the first dot will be equal to $k\cdot\delta$ where
+        \dim_set:Nn \l_tmpa_dim 
+          { 
+            ( \g_@@_x_final_dim - \g_@@_x_initial_dim ) *
+            \dim_ratio:nn { 0.45 em } \l_@@_l_dim 
+          }
+        \dim_set:Nn \l_tmpb_dim 
+          { 
+            ( \g_@@_y_final_dim - \g_@@_y_initial_dim ) *
+            \dim_ratio:nn { 0.45 em } \l_@@_l_dim
+          }
+%    \end{macrocode}
+%
+% The length $\ell$ is the length of the dotted line. We note $\Delta$ the
+% length between two dots and $n$ the number of intervals between dots. We note
+% $\delta = \frac12(\ell - n \Delta)$. The distance between the initial
+% extremity of the line and the first dot will be equal to $k\cdot\delta$ where 
 % $k=0$, $1$ or $2$. We first compute this number $k$ in |\l_tmpb_int|.
 %    \begin{macrocode}
-                      \int_set:Nn \l_tmpb_int
-                          {\bool_if:NTF \l_@@_initial_open_bool
-                             {\bool_if:NTF \l_@@_final_open_bool 1 0}
-                             {\bool_if:NTF \l_@@_final_open_bool 2 1}}
+        \int_set:Nn \l_tmpb_int
+          { 
+            \bool_if:NTF \l_@@_initial_open_bool
+              { \bool_if:NTF \l_@@_final_open_bool 1 0 }
+              { \bool_if:NTF \l_@@_final_open_bool 2 1 }
+          }
 %    \end{macrocode}
-% In the loop over the dots (|\int_step_inline:nnnn|), the dimensions |\g_@@_x_initial_dim| and
-% |\g_@@_y_initial_dim| will be used for the coordinates of the dots. But, before the loop, we must move until the
+% In the loop over the dots (|\int_step_inline:nnnn|), the dimensions
+% |\g_@@_x_initial_dim| and |\g_@@_y_initial_dim| will be used for the
+% coordinates of the dots. But, before the loop, we must move until the 
 % first dot.
 %
 %    \begin{macrocode}
-                      \dim_gadd:Nn \g_@@_x_initial_dim
-                          {  (\g_@@_x_final_dim - \g_@@_x_initial_dim)
-                              * \dim_ratio:nn {\l_@@_l_dim - 0.45 em * \l_tmpa_int}
-                                              {\l_@@_l_dim * 2} 
-                              * \l_tmpb_int}
+        \dim_gadd:Nn \g_@@_x_initial_dim
+          {  
+            ( \g_@@_x_final_dim - \g_@@_x_initial_dim ) *
+            \dim_ratio:nn 
+              { \l_@@_l_dim - 0.45 em * \l_tmpa_int } { \l_@@_l_dim * 2 } *
+            \l_tmpb_int
+          }
 %    \end{macrocode}
-% (In a multiplication of a dimension and an integer, the integer must always be put in second position.)
+% (In a multiplication of a dimension and an integer, the integer must always be
+% put in second position.) 
 %    \begin{macrocode}         
-                      \dim_gadd:Nn \g_@@_y_initial_dim 
-                          {   (\g_@@_y_final_dim - \g_@@_y_initial_dim)
-                             * \dim_ratio:nn {\l_@@_l_dim - 0.45 em * \l_tmpa_int}
-                                             {\l_@@_l_dim * 2}
-                             * \l_tmpb_int}
-                      \begin{tikzpicture}[overlay]
-                      \int_step_inline:nnnn 0 1 \l_tmpa_int
-                         { \pgfpathcircle{\pgfpoint{\g_@@_x_initial_dim}
-                                                   {\g_@@_y_initial_dim}}
-                                         {0.53pt}
-                           \pgfusepath{fill}
-                           \dim_gadd:Nn \g_@@_x_initial_dim \l_tmpa_dim
-                           \dim_gadd:Nn \g_@@_y_initial_dim \l_tmpb_dim }
-                      \end{tikzpicture}}
-}
+        \dim_gadd:Nn \g_@@_y_initial_dim 
+          {   
+            ( \g_@@_y_final_dim - \g_@@_y_initial_dim ) * 
+            \dim_ratio:nn 
+              { \l_@@_l_dim - 0.45 em * \l_tmpa_int } 
+              { \l_@@_l_dim * 2 } * 
+            \l_tmpb_int
+          }
+        \begin { tikzpicture } [ overlay ]
+          \int_step_inline:nnnn 0 1 \l_tmpa_int
+            { 
+              \pgfpathcircle 
+                { \pgfpoint { \g_@@_x_initial_dim } { \g_@@_y_initial_dim } }
+                { 0.53 pt }
+              \pgfusepath { fill }
+              \dim_gadd:Nn \g_@@_x_initial_dim \l_tmpa_dim
+              \dim_gadd:Nn \g_@@_y_initial_dim \l_tmpb_dim 
+            }
+        \end { tikzpicture } 
+      }
+  }
 %    \end{macrocode}
 %
 % \subsection{User commands available in the new environments}
 %
-% We give new names for the commands |\ldots|, |\cdots|, |\vdots| and |\ddots| because these commands will be
-% redefined (if the option |renew-dots| is used).
+% We give new names for the commands |\ldots|, |\cdots|, |\vdots| and |\ddots|
+% because these commands will be redefined (if the option |renew-dots| is used).
 %    \begin{macrocode}
 \cs_set_eq:NN \@@_ldots \ldots
 \cs_set_eq:NN \@@_cdots \cdots
@@ -3395,56 +3843,70 @@ version 2005/12/01 or later.
 %    \end{macrocode}
 %
 % \interitem
-% The command |\@@_add_to_empty_cells:| adds the current cell to |\g_@@_empty_cells_seq| which is the list of the
-% empty cells (the cells explicitly declared ``empty'': there may be, of course, other empty cells in the matrix).
+% The command |\@@_add_to_empty_cells:| adds the current cell to
+% |\g_@@_empty_cells_seq| which is the list of the empty cells (the cells
+% explicitly declared ``empty'': there may be, of course, other empty cells in
+% the matrix). 
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_add_to_empty_cells:
-    {\seq_gput_right:Nx \g_@@_empty_cells_seq
-          {\int_use:N \g_@@_row_int-
-           \int_use:N \g_@@_column_int}}
+  { 
+    \seq_gput_right:Nx \g_@@_empty_cells_seq
+      { \int_use:N \g_@@_row_int - \int_use:N \g_@@_column_int }
+  }
 %    \end{macrocode}
 %
 % \interitem 
-% The commands |\@@_Ldots|, |\@@_Cdots|, |\@@_Vdots|, |\@@_Ddots| and |\@@_Iddots| will be linked to |\Ldots|,
-% |\Cdots|, |\Vdots|, |\Ddots| and |\Iddots| in the environments |{NiceArray}| (the other environments of
-% \pkg{nicematrix} rely upon |{NiceArray}|).
-%    \begin{macrocode}
-\NewDocumentCommand \@@_Ldots {s}
-    {\bool_if:nF {#1} {\@@_instruction_of_type:n {Ldots}}
-     \bool_if:NF \l_@@_nullify_dots_bool {\phantom \@@_ldots}
-     \@@_add_to_empty_cells:}
+% The commands |\@@_Ldots|, |\@@_Cdots|, |\@@_Vdots|, |\@@_Ddots| and
+% |\@@_Iddots| will be linked to |\Ldots|, |\Cdots|, |\Vdots|, |\Ddots| and
+% |\Iddots| in the environments |{NiceArray}| (the other environments of
+% \pkg{nicematrix} rely upon |{NiceArray}|). 
+%    \begin{macrocode}
+\NewDocumentCommand \@@_Ldots { s }
+  { 
+    \bool_if:nF { #1 } { \@@_instruction_of_type:n { Ldots } }
+    \bool_if:NF \l_@@_nullify_dots_bool { \phantom \@@_ldots }
+    \@@_add_to_empty_cells:
+  }
 %    \end{macrocode}
 %
 % \bigskip
 %    \begin{macrocode}
-\NewDocumentCommand \@@_Cdots {s}
-    {\bool_if:nF {#1} {\@@_instruction_of_type:n {Cdots}}
-     \bool_if:NF \l_@@_nullify_dots_bool {\phantom \@@_cdots}
-     \@@_add_to_empty_cells:}
+\NewDocumentCommand \@@_Cdots { s }
+  { 
+    \bool_if:nF { #1 } { \@@_instruction_of_type:n { Cdots } }
+    \bool_if:NF \l_@@_nullify_dots_bool { \phantom \@@_cdots }
+    \@@_add_to_empty_cells:
+  }
 %    \end{macrocode}
 %
 % \bigskip
 %    \begin{macrocode}
-\NewDocumentCommand \@@_Vdots {s}
-    {\bool_if:nF {#1} {\@@_instruction_of_type:n {Vdots}}
-     \bool_if:NF \l_@@_nullify_dots_bool {\phantom \@@_vdots}
-     \@@_add_to_empty_cells:}
+\NewDocumentCommand \@@_Vdots { s }
+  {
+    \bool_if:nF { #1 } { \@@_instruction_of_type:n { Vdots } }
+    \bool_if:NF \l_@@_nullify_dots_bool { \phantom \@@_vdots }
+    \@@_add_to_empty_cells:
+  }
 %    \end{macrocode}
 %
 % \bigskip
 %    \begin{macrocode}
-\NewDocumentCommand \@@_Ddots {s}
-    {\bool_if:nF {#1} {\@@_instruction_of_type:n {Ddots}}
-     \bool_if:NF \l_@@_nullify_dots_bool {\phantom \@@_ddots}
-     \@@_add_to_empty_cells:}
+\NewDocumentCommand \@@_Ddots { s }
+  { 
+    \bool_if:nF { #1 } { \@@_instruction_of_type:n { Ddots } }
+    \bool_if:NF \l_@@_nullify_dots_bool { \phantom \@@_ddots }
+    \@@_add_to_empty_cells:
+  }
 %    \end{macrocode}
 %
 % \bigskip
 %    \begin{macrocode}
-\NewDocumentCommand \@@_Iddots {s}
-    {\bool_if:nF {#1} {\@@_instruction_of_type:n {Iddots}}
-     \bool_if:NF \l_@@_nullify_dots_bool {\phantom \@@_iddots}
-     \@@_add_to_empty_cells:}
+\NewDocumentCommand \@@_Iddots { s }
+  { 
+    \bool_if:nF { #1 } { \@@_instruction_of_type:n { Iddots } }
+    \bool_if:NF \l_@@_nullify_dots_bool { \phantom \@@_iddots }
+    \@@_add_to_empty_cells:
+  }
 %    \end{macrocode}
 %
 %
@@ -3452,145 +3914,189 @@ version 2005/12/01 or later.
 % The command |\@@_Hspace:| will be linked to |\hspace| in |{NiceArray}|.
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_Hspace:
-  {\@@_add_to_empty_cells:
-   \hspace}
+  { 
+   \@@_add_to_empty_cells:
+   \hspace
+  }
 %    \end{macrocode}
 %
 %
 % \bigskip
-% In the environment |{NiceArray}|, the command |\multicolumn| will be linked to the following command
-% |\@@_multicolumn:nnn|.
+% In the environment |{NiceArray}|, the command |\multicolumn| will be linked to
+% the following command |\@@_multicolumn:nnn|.
 %    \begin{macrocode}
 \cs_set_eq:NN \@@_old_multicolumn \multicolumn
 \cs_new:Nn \@@_multicolumn:nnn
-       {\@@_old_multicolumn{#1}{#2}{#3}
-        \int_compare:nNnT #1 > 1
-            {\seq_gput_left:Nx \g_@@_multicolumn_cells_seq
-                               {\int_eval:n \g_@@_row_int - 
-                                \int_use:N \g_@@_column_int}
-             \seq_gput_left:Nn \g_@@_multicolumn_sizes_seq {#1}}
-        \int_gadd:Nn \g_@@_column_int {#1-1}}
+  { 
+    \@@_old_multicolumn { #1 } { #2 } { #3 }
+    \int_compare:nNnT #1 > 1
+      {
+        \seq_gput_left:Nx \g_@@_multicolumn_cells_seq
+          { \int_eval:n \g_@@_row_int - \int_use:N \g_@@_column_int }
+        \seq_gput_left:Nn \g_@@_multicolumn_sizes_seq { #1 } 
+      }
+    \int_gadd:Nn \g_@@_column_int { #1 - 1 }
+  }
 %    \end{macrocode}
 %
 %
 % \bigskip
-% The command |\@@_Hdotsfor| will be linked to |\Hdotsfor| in |{NiceArray}|. This command uses an optional
-% argument like |\hdotsfor| but this argument is discarded (in |\hdotsfor|, this argument is used for fine tuning
-% of the space beetween two consecutive dots). 
-% Tikz nodes are created for all the cells of the array, even the implicit cells of the |\Hdotsfor|.
-%    \begin{macrocode}
-\NewDocumentCommand {\@@_Hdotsfor} {O{} m}
-     {\tl_gput_right:Nx \g_@@_lines_to_draw_tl 
-           {\exp_not:N \@@_draw_Hdotsfor:nnn
-                       {\int_use:N \g_@@_row_int} 
-                       {\int_use:N \g_@@_column_int}
-                       {#2}}
-      \prg_replicate:nn {#2-1} {&}}
+% The command |\@@_Hdotsfor| will be linked to |\Hdotsfor| in |{NiceArray}|.
+% This command uses an optional argument like |\hdotsfor| but this argument is
+% discarded (in |\hdotsfor|, this argument is used for fine tuning of the space
+% beetween two consecutive dots). Tikz nodes are created for all the cells of
+% the array, even the implicit cells of the |\Hdotsfor|. 
+%    \begin{macrocode}
+\NewDocumentCommand \@@_Hdotsfor { O { } m }
+  { 
+    \tl_gput_right:Nx \g_@@_lines_to_draw_tl 
+      { 
+        \exp_not:N \@@_draw_Hdotsfor:nnn
+          { \int_use:N \g_@@_row_int } 
+          { \int_use:N \g_@@_column_int }
+          { #2 }
+      }
+    \prg_replicate:nn { #2 - 1 } { & } 
+  }
 %    \end{macrocode}
 % 
 % \medskip
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_draw_Hdotsfor:nnn
-       {\bool_set_false:N \l_@@_initial_open_bool
-        \bool_set_false:N \l_@@_final_open_bool
+  { 
+    \bool_set_false:N \l_@@_initial_open_bool
+    \bool_set_false:N \l_@@_final_open_bool
 %    \end{macrocode}
 % For the row, it's easy.
 %    \begin{macrocode}
-        \int_set:Nn \l_@@_initial_i_int {#1}
-        \int_set:Nn \l_@@_final_i_int {#1}
+    \int_set:Nn \l_@@_initial_i_int { #1 }
+    \int_set:Nn \l_@@_final_i_int { #1 }
 %    \end{macrocode}
 % For the column, it's a bit more complicated.
 %    \begin{macrocode}
-        \int_compare:nNnTF #2 = 1
-              {\int_set:Nn \l_@@_initial_j_int 1
-               \bool_set_true:N \l_@@_initial_open_bool}
-              {\int_set:Nn \l_tmpa_int {#2-1}
-               \@@_if_not_empty_cell:nnTF \l_@@_initial_i_int \l_tmpa_int
-                 {\int_set:Nn \l_@@_initial_j_int {#2-1}}
-                 {\int_set:Nn \l_@@_initial_j_int {#2}
-                  \bool_set_true:N \l_@@_initial_open_bool}}
-        \int_compare:nNnTF {#2+#3-1} = \g_@@_column_int
-              {\int_set:Nn \l_@@_final_j_int {#2+#3-1}
-               \bool_set_true:N \l_@@_final_open_bool}
-              {\int_set:Nn \l_tmpa_int {#2+#3}
-               \@@_if_not_empty_cell:nnTF \l_@@_final_i_int \l_tmpa_int
-                 {\int_set:Nn \l_@@_final_j_int {#2+#3}}
-                 {\int_set:Nn \l_@@_final_j_int {#2+#3-1}
-                  \bool_set_true:N \l_@@_final_open_bool}}
-        \bool_if:nT {\l_@@_initial_open_bool || \l_@@_final_open_bool}
-                    \@@_create_extra_nodes: 
-        \@@_actually_draw_Ldots:}
+    \int_compare:nNnTF #2 = 1
+      { 
+        \int_set:Nn \l_@@_initial_j_int 1
+        \bool_set_true:N \l_@@_initial_open_bool
+      }
+      {
+        \int_set:Nn \l_tmpa_int { #2 - 1 }
+        \@@_if_not_empty_cell:nnTF \l_@@_initial_i_int \l_tmpa_int
+          { \int_set:Nn \l_@@_initial_j_int { #2 - 1 } }
+          { 
+            \int_set:Nn \l_@@_initial_j_int {#2}
+            \bool_set_true:N \l_@@_initial_open_bool
+          }
+      }
+    \int_compare:nNnTF { #2 + #3 -1 } = \g_@@_column_int
+      { 
+        \int_set:Nn \l_@@_final_j_int { #2 + #3 - 1 }
+        \bool_set_true:N \l_@@_final_open_bool
+      }
+      {
+        \int_set:Nn \l_tmpa_int { #2 + #3 }
+        \@@_if_not_empty_cell:nnTF \l_@@_final_i_int \l_tmpa_int
+          { \int_set:Nn \l_@@_final_j_int { #2 + #3 } }
+          { 
+            \int_set:Nn \l_@@_final_j_int { #2 + #3 - 1 }
+            \bool_set_true:N \l_@@_final_open_bool
+          }
+      }
+    \bool_if:nT { \l_@@_initial_open_bool || \l_@@_final_open_bool }
+      \@@_create_extra_nodes: 
+    \@@_actually_draw_Ldots:
+  }
 %    \end{macrocode}
 % 
 %
 %
 % \subsection{The command \textbackslash line accessible in code-after}
 %
-% In the |code-after|, the command |\@@_line:nn| will be linked to |\line|. This command takes two arguments which
-% are the specification of two cells in the array (in the format $i$-$j$) and draws a dotted line between these cells.
+% In the |code-after|, the command |\@@_line:nn| will be linked to |\line|. This
+% command takes two arguments which are the specification of two cells in the
+% array (in the format $i$-$j$) and draws a dotted line between these cells. 
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_line:nn
-     {\dim_zero_new:N \g_@@_x_initial_dim
-      \dim_zero_new:N \g_@@_y_initial_dim
-      \dim_zero_new:N \g_@@_x_final_dim
-      \dim_zero_new:N \g_@@_y_final_dim
-      \@@_bool_new:N \l_@@_initial_open_bool
-      \@@_bool_new:N \l_@@_final_open_bool
-      \begin{tikzpicture}
-         \path~(#1)~--~(#2)~node[at~start]~(i)~{}~node[at~end]~(f)~{} ;
-         \tikz@parse@node\pgfutil@firstofone (i)
-         \dim_gset:Nn \g_@@_x_initial_dim \pgf@x
-         \dim_gset:Nn \g_@@_y_initial_dim \pgf@y
-         \tikz@parse@node\pgfutil@firstofone (f)
-         \dim_gset:Nn \g_@@_x_final_dim \pgf@x
-         \dim_gset:Nn \g_@@_y_final_dim \pgf@y
-      \end{tikzpicture}  
-      \@@_draw_tikz_line:}
+  {
+    \dim_zero_new:N \g_@@_x_initial_dim
+    \dim_zero_new:N \g_@@_y_initial_dim
+    \dim_zero_new:N \g_@@_x_final_dim
+    \dim_zero_new:N \g_@@_y_final_dim
+    \bool_set_false:N \l_@@_initial_open_bool
+    \bool_set_false:N \l_@@_final_open_bool
+    \begin { tikzpicture }
+       \path~(#1)~--~(#2)~node[at~start]~(i)~{}~node[at~end]~(f)~{} ;
+       \tikz@parse@node \pgfutil@firstofone ( i )
+       \dim_gset:Nn \g_@@_x_initial_dim \pgf@x
+       \dim_gset:Nn \g_@@_y_initial_dim \pgf@y
+       \tikz@parse@node \pgfutil@firstofone ( f )
+       \dim_gset:Nn \g_@@_x_final_dim \pgf@x
+       \dim_gset:Nn \g_@@_y_final_dim \pgf@y
+    \end { tikzpicture }  
+    \@@_draw_tikz_line:
+  }
 %    \end{macrocode}
 % 
-% The commands |\Ldots|, |\Cdots|, |\Vdots|, |\Ddots|, |\Iddots| don't use this command because they have to do
-% other settings (for example, the diagonal lines must be parallelized).
+% The commands |\Ldots|, |\Cdots|, |\Vdots|, |\Ddots|, |\Iddots| don't use this
+% command because they have to do other settings (for example, the diagonal
+% lines must be parallelized). 
 %
 %
 %
 % \subsection{The environment \{NiceMatrixBlock\}}
 %
-% The following flag will be raised when all the columns of the environments of the block must have the same width
-% in ``auto'' mode.
+% The following flag will be raised when all the columns of the environments of
+% the block must have the same width in ``auto'' mode.
 %    \begin{macrocode}
 \bool_new:N \l_@@_block_auto_columns_width_bool
 %    \end{macrocode}
 %
 % \bigskip
-% As of now, there is only one option available for the environment |{NiceMatrixBlock}|.
-%    \begin{macrocode}
-\keys_define:nn {NiceMatrix/NiceMatrixBlock} 
-      {auto-columns-width .code:n = 
-                           {\bool_set_true:N \l_@@_block_auto_columns_width_bool
-                            \dim_gzero_new:N \g_@@_max_cell_width_dim
-                            \bool_set_true:N \l_@@_auto_columns_width_bool}}
+% As of now, there is only one option available for the environment
+% |{NiceMatrixBlock}|. 
+%    \begin{macrocode}
+\keys_define:nn { NiceMatrix / NiceMatrixBlock } 
+  {
+    auto-columns-width .code:n = 
+      { 
+        \bool_set_true:N \l_@@_block_auto_columns_width_bool
+        \dim_gzero_new:N \g_@@_max_cell_width_dim
+        \bool_set_true:N \l_@@_auto_columns_width_bool
+      }
+  }
 %    \end{macrocode}
 %
 % \bigskip
 %    \begin{macrocode}
-\NewDocumentEnvironment {NiceMatrixBlock} {!O{}}
-    {\keys_set:nn {NiceMatrix/NiceMatrixBlock} {#1}
-     \int_zero_new:N \l_@@_first_env_block_int
-     \int_set:Nn \l_@@_first_env_block_int {\g_@@_env_int + 1}}
+\NewDocumentEnvironment { NiceMatrixBlock } { ! O { } }
+  {
+    \keys_set:nn { NiceMatrix / NiceMatrixBlock } { #1 }
+    \int_zero_new:N \l_@@_first_env_block_int
+    \int_set:Nn \l_@@_first_env_block_int { \g_@@_env_int + 1 }
+  }
 %    \end{macrocode}
 %
 % \medskip
-% At the end of the environment |{NiceMatrixBlock}|, we write in the main |.aux| file instructions for the column
-% width of all the environments of the block (that's why we have stored the number of the first environment of the
-% block in the counter |\l_@@_first_env_block_int|).
-%    \begin{macrocode}
-    {\bool_if:NT \l_@@_block_auto_columns_width_bool
-          {\iow_now:Nn \@mainaux \ExplSyntaxOn
-           \int_step_inline:nnnn \l_@@_first_env_block_int 1 \g_@@_env_int
-               {\iow_now:Nx \@mainaux         
-                   {\cs_gset:cpn {@@_max_cell_width_##1} 
-                                 {\dim_use:N \g_@@_max_cell_width_dim}}}
-           \iow_now:Nn \@mainaux \ExplSyntaxOff}}
+% At the end of the environment |{NiceMatrixBlock}|, we write in the main |.aux|
+% file instructions for the column width of all the environments of the block
+% (that's why we have stored the number of the first environment of the block in
+% the counter |\l_@@_first_env_block_int|). 
+%    \begin{macrocode}
+  { 
+    \bool_if:NT \l_@@_block_auto_columns_width_bool
+      {
+        \iow_now:Nn \@mainaux \ExplSyntaxOn
+        \int_step_inline:nnnn \l_@@_first_env_block_int 1 \g_@@_env_int
+          { 
+            \iow_now:Nx \@mainaux         
+              { 
+                \cs_gset:cpn { @@ _ max _ cell _ width _ ##1 } 
+                  { \dim_use:N \g_@@_max_cell_width_dim }
+              }
+          }
+        \iow_now:Nn \@mainaux \ExplSyntaxOff
+      }
+  }
 %    \end{macrocode}
 %
 % \subsection{The environment \{pNiceArrayC\} and its variants}
@@ -3598,175 +4104,190 @@ version 2005/12/01 or later.
 % The code in this section can be removed without affecting the previous code.
 % 
 % \medskip
-% First, we define a set of options for the environment |{pNiceArrayC}| and its variants. This set of keys is named   
-% |NiceMatrix/NiceArrayC| even though there is no environment called |{NiceArrayC}|.
-%
-%    \begin{macrocode}
-\keys_define:nn {NiceMatrix/NiceArrayC}
-     {parallelize-diags .bool_set:N       = \l_@@_parallelize_diags_bool,
-      parallelize-diags .default:n        = true,
-      renew-dots        .bool_set:N       = \l_@@_renew_dots_bool,
-      renew-dots        .default:n        = true,
-      nullify-dots      .bool_set:N       = \l_@@_nullify_dots_bool ,
-      nullify-dots      .default:n        = true,
-      code-for-last-col .tl_set:N         = \l_@@_code_for_last_col_tl,
-      code-for-last-col .value_required:n = true,
-      columns-width     .code:n           = \str_if_eq:nnTF {#1} {auto}
-                                            {\bool_set_true:N 
-                                                   \l_@@_auto_columns_width_bool}
-                                            {\dim_set:Nn \l_@@_columns_width_dim {#1}},
-      columns-width     .value_required:n = true,
-      name              .code:n           = {\seq_if_in:NnTF \g_@@_names_seq {#1}
-                                                {\@@_error:nn {Duplicate~name} {#1}}
-                                                {\seq_gput_left:Nn \g_@@_names_seq {#1}}
-                                             \tl_set:Nn \l_@@_name_tl {#1}},
-      name              .value_required:n = true,
-      code-after        .tl_set:N          = \l_@@_code_after_tl,
-      code-after        .initial:n         = \c_empty_tl,
-      code-after        .value_required:n = true,
-      create-extra-nodes  .bool_set:N   = \l_@@_extra_nodes_bool,
-      create-extra-nodes  .default:n    = true,
-      left-margin  .dim_set:N  = \l_@@_left_margin_dim,
-      left-margin  .default:n  = \arraycolsep,
-      right-margin .dim_set:N  = \l_@@_right_margin_dim,
-      right-margin .default:n  = \arraycolsep,
-      extra-left-margin  .dim_set:N  = \l_@@_extra_left_margin_dim,
-      extra-right-margin .dim_set:N  = \l_@@_extra_right_margin_dim,
-      unknown .code:n  = \@@_error:n {Unknown~option~for~NiceArrayC}}
-%    \end{macrocode}
-%
-%    \begin{macrocode}
-\msg_new:nnnn {nicematrix}
-              {Unknown~option~for~NiceArrayC}
-              {The~option~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~environment~
-               \{\@currenvir\}.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~options,~type~H~<return>.}
-              {The~available~options~are~(in~alphabetic~order):~
-               code-after,~
-               code-for-last-col,~
-               columns-width,~
-               create-extra-nodes,~
-               extra-left-margin,~
-               extra-right-margin,~
-               left-margin,~
-               name,~
-               nullify-dots,~
-               parallelize-diags~
-               renew-dots~
-               and~right-margin.}
+% First, we define a set of options for the environment |{pNiceArrayC}| and its
+% variants. This set of keys is named |NiceMatrix/NiceArrayC| even though there
+% is no environment called |{NiceArrayC}|. 
+%
+%    \begin{macrocode}
+\keys_define:nn { NiceMatrix / NiceArrayC }
+  { 
+    code-for-last-col .tl_set:N = \l_@@_code_for_last_col_tl ,
+    code-for-last-col .value_required:n = true ,
+    unknown .code:n  = \@@_error:n { Unknown~option~for~NiceArrayC }
+  }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\@@_msg_new:nnn { Unknown~option~for~NiceArrayC }
+  { 
+    The~option~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~environment~
+    \{\@currenvir\}. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~options,~type~H~<return>.
+  }
+  { 
+    The~available~options~are~(in~alphabetic~order):~
+    code-after,~
+    code-for-last-col,~
+    columns-width,~
+    create-extra-nodes,~
+    extra-left-margin,~
+    extra-right-margin,~
+    left-margin,~
+    name,~
+    nullify-dots,~
+    parallelize-diags~
+    renew-dots~
+    and~right-margin.
+  }
 %    \end{macrocode}
 %
 % \bigskip
-% In the environment |{pNiceArrayC}| (and its variants), the last column is composed with instructions
-% |\hbox_overlap_right:n| (this instruction may be seen as the \pkg{expl3} equivalent of the classical command
-% |\rlap|). After the composition of the array, an horizontal skip is inserted to compensate for these
-% overlapping boxes.
+% In the environment |{pNiceArrayC}| (and its variants), the last column is
+% composed with instructions |\hbox_overlap_right:n| (this instruction may be
+% seen as the \pkg{expl3} equivalent of the classical command |\rlap|). After
+% the composition of the array, an horizontal skip is inserted to compensate for
+% these overlapping boxes.
 %
 % \medskip
-% The command |\@@_NiceArrayC:n| will be used in |{NiceArrayCwithDelims}| but also in the environment
-% |{NiceArrayRCwithDelims}|.
+% The command |\@@_NiceArrayC:n| will be used in |{NiceArrayCwithDelims}| but
+% also in the environment |{NiceArrayRCwithDelims}|.
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_NiceArrayC:n
-    {\bool_set_true:N \l_@@_exterior_column_bool
-     \begin{NiceArray}
+  {
+    \bool_set_true:N \l_@@_exterior_column_bool
+    \begin { NiceArray }
 %    \end{macrocode}
-% The beginning of the preamble is the argument of the environment |{pNiceArrayC}|. 
+% The beginning of the preamble is the argument of the environment
+% |{pNiceArrayC}|.  
 %    \begin{macrocode}
-             {#1
+      { #1
 %    \end{macrocode}
 % 
-% However, we add a last column with its own specification. For a cell in this last column, the first operation is
-% to store the content of the cell in the box |\l_tmpa_box|. This is allowed in \pkg{expl3} with the construction
-% |\hbox_set:Nw \l_tmpa_box| ... |\hbox_set_end:|.
+% However, we add a last column with its own specification. For a cell in this
+% last column, the first operation is to store the content of the cell in the
+% box |\l_tmpa_box|. This is allowed in \pkg{expl3} with the construction
+% |\hbox_set:Nw \l_tmpa_box| ... |\hbox_set_end:|. 
 %    \begin{macrocode}
-                >{\int_gincr:N \g_@@_column_int
-                 \int_gset:Nn \g_@@_column_total_int
-                              {\int_max:nn \g_@@_column_total_int \g_@@_column_int}
-                  \hbox_set:Nw \l_tmpa_box $ % $
-                     \l_@@_code_for_last_col_tl
-                 }
-                l
+        > 
+          { 
+            \int_gincr:N \g_@@_column_int
+            \int_gset:Nn \g_@@_column_total_int
+              { \int_max:nn \g_@@_column_total_int \g_@@_column_int }
+            \hbox_set:Nw \l_tmpa_box $ % $
+              \l_@@_code_for_last_col_tl
+          }
+        l
 %    \end{macrocode}
 % 
-% We actualize the value of |\g_@@_with_last_col_dim| which, at the end of the array, will contain the maximal width
-% of the cells of the last column (thus, it will be equal to the width of the last column).
+% We actualize the value of |\g_@@_with_last_col_dim| which, at the end of the
+% array, will contain the maximal width of the cells of the last column (thus,
+% it will be equal to the width of the last column). 
 %    \begin{macrocode}
-                <{   $ % $
-                  \hbox_set_end:
-                  \dim_gset:Nn \g_@@_width_last_col_dim
-                     {\dim_max:nn \g_@@_width_last_col_dim
-                                  {\box_wd:N \l_tmpa_box}}
-                  \skip_horizontal:n {-2\arraycolsep}
+        < { $ % $
+            \hbox_set_end:
+            \dim_gset:Nn \g_@@_width_last_col_dim
+               { 
+                 \dim_max:nn 
+                   \g_@@_width_last_col_dim
+                   { \box_wd:N \l_tmpa_box }
+               }
+            \skip_horizontal:n { - 2 \arraycolsep }
 %    \end{macrocode}
 % The content of the cell is inserted in an overlapping position.
 %    \begin{macrocode}
-                  \hbox_overlap_right:n
-                       {\skip_horizontal:n
-                               { 2\arraycolsep + \l_@@_right_margin_dim
-                                               + \l_@@_extra_right_margin_dim}
-                        \tikz[remember~picture, inner~sep=0pt, minimum~width=0pt, baseline]
-                           \node [anchor=base,
-                                  name = nm-\int_use:N \g_@@_env_int-
-                                            \int_use:N \g_@@_row_int-
-                                            \int_use:N \g_@@_column_int,
-                                  alias = \tl_if_empty:NF \l_@@_name_tl
-                                            {\l_@@_name_tl-
-                                             \int_use:N \g_@@_row_int-
-                                             \int_use:N \g_@@_column_int}]
-                                   {\box_use:N \l_tmpa_box} ; } }}}
-%    \end{macrocode}
-% This ends the preamble of the array that will be constructed (a rather long preamble, indeed).
+            \hbox_overlap_right:n
+              { 
+                \skip_horizontal:n
+                  { 
+                    2 \arraycolsep + 
+                    \l_@@_right_margin_dim + 
+                    \l_@@_extra_right_margin_dim
+                  }
+                \tikz 
+                  [ 
+                    remember~picture , 
+                    inner~sep = \c_zero_dim , 
+                    minimum~width = \c_zero_dim , 
+                    baseline
+                  ]
+                \node 
+                  [ 
+                    anchor = base ,
+                    name = 
+                      nm -
+                      \int_use:N \g_@@_env_int -
+                      \int_use:N \g_@@_row_int -
+                      \int_use:N \g_@@_column_int ,
+                    alias = 
+                      \str_if_empty:NF \l_@@_name_str
+                        { 
+                          \l_@@_name_str -
+                          \int_use:N \g_@@_row_int -
+                          \int_use:N \g_@@_column_int
+                        }
+                  ]
+                  { \box_use:N \l_tmpa_box } ; 
+              } 
+          }
+      }
+  }
+%    \end{macrocode}
 %
 % \bigskip
-% The environments of the type of |{pNiceArrayC}| will be constructed over |{NiceArrayCwithDelims}|. The first
-% two arguments of this environment are the left and the right delimiter.
-%    \begin{macrocode}
-\NewDocumentEnvironment{NiceArrayCwithDelims} {mm O{} m !O{}}
-    {\dim_gzero_new:N \g_@@_width_last_col_dim
-     \keys_set:nn {NiceMatrix/NiceArrayC} {#3,#5}
-     \bool_set_false:N \l_@@_exterior_arraycolsep_bool
-     \tl_set:Nn \l_@@_pos_env_tl c
-     \left#1
-     \@@_NiceArrayC:n {#4}}
-    {\end{NiceArray}
-     \right#2
-     \skip_horizontal:n \g_@@_width_last_col_dim
-    }
+% The environments of the type of |{pNiceArrayC}| will be constructed over
+% |{NiceArrayCwithDelims}|. The first two arguments of this environment are the
+% left and the right delimiter. 
+%    \begin{macrocode}
+\NewDocumentEnvironment { NiceArrayCwithDelims } { m m O { } m ! O { } }
+  {
+    \dim_gzero_new:N \g_@@_width_last_col_dim
+    \keys_set:nn { NiceMatrix / NiceArrayC } { #3 , #5 }
+    \bool_set_false:N \l_@@_exterior_arraycolsep_bool
+    \str_set:Nn \l_@@_pos_env_str c
+    \left #1
+    \@@_NiceArrayC:n { #4 }
+  }
+  {
+    \end { NiceArray }
+    \right #2
+    \skip_horizontal:n \g_@@_width_last_col_dim
+  }
 %    \end{macrocode}
 %         
 %                                                                             
 % \bigskip
-% In the following environments, we don't use the form with |\begin{...}| and |\end{...}| because we use
-% |\@currenvir| in the error message for an unknown option.
+% In the following environments, we don't use the form with |\begin{...}| and
+% |\end{...}| because we use |\@currenvir| in the error message for an unknown
+% option. 
 %    \begin{macrocode}                       
-\NewDocumentEnvironment {pNiceArrayC} {}
-    {\NiceArrayCwithDelims{(}{)}}
-    {\endNiceArrayCwithDelims}
+\NewDocumentEnvironment { pNiceArrayC } { }
+  { \NiceArrayCwithDelims ( ) }
+  { \endNiceArrayCwithDelims }
 %    \end{macrocode}
 %
 %    \begin{macrocode}                       
-\NewDocumentEnvironment {vNiceArrayC} {}
-    {\NiceArrayCwithDelims{|}{|}}
-    {\endNiceArrayCwithDelims}
+\NewDocumentEnvironment { vNiceArrayC } { }
+  { \NiceArrayCwithDelims | | }
+  { \endNiceArrayCwithDelims }
 %    \end{macrocode}
 %
 %    \begin{macrocode}                       
-\NewDocumentEnvironment {VNiceArrayC} {}
-    {\NiceArrayCwithDelims{\|}{\|}}
-    {\endNiceArrayCwithDelims}
+\NewDocumentEnvironment { VNiceArrayC } { }
+  { \NiceArrayCwithDelims \|  \| }
+  { \endNiceArrayCwithDelims }
 %    \end{macrocode}
 %
 %    \begin{macrocode}                       
-\NewDocumentEnvironment {bNiceArrayC} {}
-    {\NiceArrayCwithDelims{[}{]}}
-    {\endNiceArrayCwithDelims}
+\NewDocumentEnvironment { bNiceArrayC } { }
+  { \NiceArrayCwithDelims [ ] }
+  { \endNiceArrayCwithDelims }
 %    \end{macrocode}
 %
 %    \begin{macrocode}                       
-\NewDocumentEnvironment {BNiceArrayC} {}
-    {\NiceArrayCwithDelims{\{}{\}}}
-    {\endNiceArrayCwithDelims}
+\NewDocumentEnvironment { BNiceArrayC } { }
+  { \NiceArrayCwithDelims \{  \} }
+  { \endNiceArrayCwithDelims }
 %    \end{macrocode}
 %    
 %
@@ -3777,129 +4298,124 @@ version 2005/12/01 or later.
 %
 % \bigskip
 %    \begin{macrocode}
-\keys_define:nn {NiceMatrix/NiceArrayRC}
-  {parallelize-diags    .bool_set:N = \l_@@_parallelize_diags_bool,
-   parallelize-diags    .default:n  = true,
-   renew-dots           .bool_set:N = \l_@@_renew_dots_bool,
-   renew-dots           .default:n  = true,
-   nullify-dots         .bool_set:N = \l_@@_nullify_dots_bool ,
-   nullify-dots         .default:n  = true,
-   code-for-first-row   .tl_set:N   = \l_@@_code_for_first_row_tl,
-   code-for-first-row    .value_required:n = true,
-   code-for-last-col    .tl_set:N   = \l_@@_code_for_last_col_tl,
-   code-for-last-col    .value_required:n = true,
-   columns-width        .code:n     = \str_if_eq:nnTF {#1} {auto}
-                                         {\bool_set_true:N 
-                                                \l_@@_auto_columns_width_bool}
-                                         {\dim_set:Nn \l_@@_columns_width_dim {#1}},
-   columns-width        .value_required:n = true,
-   name                 .code:n     = {\seq_if_in:NnTF \g_@@_names_seq {#1}
-                                          {\@@_error:nn {Duplicate~name} {#1}}
-                                          {\seq_gput_left:Nn \g_@@_names_seq {#1}}
-                                       \tl_set:Nn \l_@@_name_tl {#1}},
-   code-after           .tl_set:N    = \l_@@_code_after_tl,
-   create-extra-nodes   .bool_set:N  = \l_@@_extra_nodes_bool,
-   create-extra-nodes   .default:n   = true,
-   left-margin  .dim_set:N  = \l_@@_left_margin_dim,
-   left-margin  .default:n  = \arraycolsep,
-   right-margin .dim_set:N  = \l_@@_right_margin_dim,
-   right-margin .default:n  = \arraycolsep,
-   extra-left-margin  .dim_set:N  = \l_@@_extra_left_margin_dim,
-   extra-right-margin .dim_set:N  = \l_@@_extra_right_margin_dim,
-   unknown .code:n  = \@@_error:n {Unknown~option~for~NiceArrayRC}}
-%    \end{macrocode}
-%
-%    \begin{macrocode}
-\msg_new:nnnn {nicematrix}
-              {Unknown~option~for~NiceArrayRC}
-              {The~option~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~environment~
-               \{\@currenvir\}.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~options,~type~H~<return>.}
-              {The~available~options~are~(in~alphabetic~order):~
-               code-after,~
-               code-for-last-col,~
-               code-for-first-row,~
-               columns-width,~
-               create-extra-nodes,~
-               extra-left-margin,~
-               extra-right-margin,~
-               left-margin,~
-               name,~
-               nullify-dots,~
-               parallelize-diags,~
-               renew-dots~
-               and~right-margin.}
-%    \end{macrocode}
-%
-%
-% The first and the second argument of the environment |{NiceArrayRCwithDelims}| are the delimiters which will be
-% used in the array. Usually, the final user will not use directly this environment |{NiceArrayRCwithDelims}|
-% because he will use one of the variants |{pNiceArrayRC}|, |{vNiceArrayRC}|, etc.
-%
-%    \begin{macrocode}
-\NewDocumentEnvironment {NiceArrayRCwithDelims} {mm O{} m !O{}}
-    {\int_zero:N \l_@@_nb_first_row_int 
-     \dim_gzero_new:N \g_@@_width_last_col_dim
-     \keys_set:nn {NiceMatrix/NiceArrayRC} {#3,#5}
-     \bool_set_false:N \l_@@_exterior_arraycolsep_bool
-     \tl_set:Nn \l_@@_pos_env_tl c
-     \box_clear_new:N \l_@@_the_array_box
-     \hbox_set:Nw \l_@@_the_array_box
-           $ % $
-           \@@_NiceArrayC:n {#4}}
-    {      \end{NiceArray}
-           $ % $
-     \hbox_set_end:
-     \dim_set:Nn \l_tmpa_dim
-            { ( \dim_max:nn {12pt} 
-                            {\g_@@_max_ht_row_one_dim + \g_@@_max_dp_row_zero_dim})
-              + \g_@@_max_ht_row_zero_dim 
-              - \g_@@_max_ht_row_one_dim }
-     \hbox_set:Nn \l_tmpa_box
-        {$ % $
-         \left#1
-         \vcenter {\skip_vertical:n {- \l_tmpa_dim}
-                   \box_use_drop:N \l_@@_the_array_box}
-         \right#2
-         $ % $
-         \skip_horizontal:n \g_@@_width_last_col_dim}
-     \box_set_ht:Nn \l_tmpa_box {\box_ht:N \l_tmpa_box + \l_tmpa_dim}
-     \box_use_drop:N \l_tmpa_box
+\keys_define:nn { NiceMatrix / NiceArrayRC }
+  {
+    code-for-first-row .tl_set:N = \l_@@_code_for_first_row_tl ,
+    code-for-first-row .value_required:n = true ,
+    code-for-last-col .tl_set:N = \l_@@_code_for_last_col_tl ,
+    code-for-last-col .value_required:n = true ,
+    unknown .code:n = \@@_error:n { Unknown~option~for~NiceArrayRC }
+  }
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\@@_msg_new:nnn { Unknown~option~for~NiceArrayRC }
+  { 
+    The~option~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~environment~
+     \{ \@currenvir \}. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~options,~type~H~<return>.
+  }
+  { 
+    The~available~options~are~(in~alphabetic~order):~
+    code-after,~
+    code-for-last-col,~
+    code-for-first-row,~
+    columns-width,~
+    create-extra-nodes,~
+    extra-left-margin,~
+    extra-right-margin,~
+    left-margin,~
+    name,~
+    nullify-dots,~
+    parallelize-diags,~
+    renew-dots~
+    and~right-margin.
+  }
+%    \end{macrocode}
+%
+%
+% The first and the second argument of the environment |{NiceArrayRCwithDelims}|
+% are the delimiters which will be used in the array. Usually, the final user
+% will not use directly this environment |{NiceArrayRCwithDelims}| because he
+% will use one of the variants |{pNiceArrayRC}|, |{vNiceArrayRC}|, etc. 
+%
+%    \begin{macrocode}
+\NewDocumentEnvironment { NiceArrayRCwithDelims } { m m O { } m ! O { } }
+  {
+    \int_zero:N \l_@@_nb_first_row_int 
+    \dim_gzero_new:N \g_@@_width_last_col_dim
+    \keys_set:nn { NiceMatrix / NiceArrayRC } { #3 , #5 }
+    \bool_set_false:N \l_@@_exterior_arraycolsep_bool
+    \str_set:Nn \l_@@_pos_env_str c
+    \box_clear_new:N \l_@@_the_array_box
+    \hbox_set:Nw \l_@@_the_array_box
+    $ % $
+    \@@_NiceArrayC:n { #4 } 
+  }
+  { 
+    \end { NiceArray }
+    $ % $
+    \hbox_set_end:
+    \dim_set:Nn \l_tmpa_dim
+      { 
+        ( 
+          \dim_max:nn
+             { 12 pt } 
+             { \g_@@_max_ht_row_one_dim + \g_@@_max_dp_row_zero_dim }
+        ) 
+        + \g_@@_max_ht_row_zero_dim - \g_@@_max_ht_row_one_dim 
+      }
+    \hbox_set:Nn \l_tmpa_box
+      {
+        $ % $
+        \left #1
+        \vcenter 
+          { 
+            \skip_vertical:n { - \l_tmpa_dim }
+            \box_use_drop:N \l_@@_the_array_box
+          }
+        \right #2
+        $ % $
+        \skip_horizontal:n \g_@@_width_last_col_dim
+      }
+    \box_set_ht:Nn \l_tmpa_box { \box_ht:N \l_tmpa_box + \l_tmpa_dim }
+    \box_use_drop:N \l_tmpa_box
     }
 %    \end{macrocode}
 % 
 % \bigskip
-% In the following environments, we don't use the form with |\begin{...}| and |\end{...}| because we use
-% |\@currenvir| in the error message for an unknown option.
+% In the following environments, we don't use the form with |\begin{...}| and
+% |\end{...}| because we use |\@currenvir| in the error message for an unknown
+% option. 
 %    \begin{macrocode}
-\NewDocumentEnvironment {pNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{(}{)}}
-     {\endNiceArrayRCwithDelims}
+\NewDocumentEnvironment { pNiceArrayRC } { }
+  { \NiceArrayRCwithDelims ( ) }
+  { \endNiceArrayRCwithDelims }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\NewDocumentEnvironment {bNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{[}{]}}
-     {\endNiceArrayRCwithDelims}
+\NewDocumentEnvironment { bNiceArrayRC } { }
+  { \NiceArrayRCwithDelims [ ] }
+  { \endNiceArrayRCwithDelims }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\NewDocumentEnvironment {vNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{|}{|}}
-     {\endNiceArrayRCwithDelims}
+\NewDocumentEnvironment { vNiceArrayRC } { }
+  { \NiceArrayRCwithDelims | | }
+  { \endNiceArrayRCwithDelims }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\NewDocumentEnvironment {VNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{\|}{\|}}
-     {\endNiceArrayRCwithDelims}
+\NewDocumentEnvironment { VNiceArrayRC } { }
+  { \NiceArrayRCwithDelims \| \| }
+  { \endNiceArrayRCwithDelims }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\NewDocumentEnvironment {BNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{\{}{\}}}
-     {\endNiceArrayRCwithDelims}
+\NewDocumentEnvironment { BNiceArrayRC } { }
+  { \NiceArrayRCwithDelims \{ \} }
+  { \endNiceArrayRCwithDelims }
 %    \end{macrocode}
 %
 %
@@ -3907,246 +4423,327 @@ version 2005/12/01 or later.
 %
 % First, two variants of the functions |\dim_min:nn| and |\dim_max:nn|.
 %    \begin{macrocode}
-\cs_generate_variant:Nn \dim_min:nn {vn}
-\cs_generate_variant:Nn \dim_max:nn {vn}
+\cs_generate_variant:Nn \dim_min:nn { v n }
+\cs_generate_variant:Nn \dim_max:nn { v n }
 %    \end{macrocode}
 %
 %
 %
 % \bigskip
-% For each row $i$, we compute two dimensions \texttt{l_@@_row_\textsl{i}_min_dim} and
-% \texttt{l_@@_row_\textsl{i}_max_dim}. The dimension \texttt{l_@@_row_\textsl{i}_min_dim} is the minimal
-% $y$-value of all the cells of the row~$i$. The dimension \texttt{l_@@_row_\textsl{i}_max_dim} is the maximal
-% $y$-value of all the cells of the row~$i$.
-%
-% Similarly, for each column $j$, we compute two dimensions \texttt{l_@@_column_\textsl{j}_min_dim} and
-% \texttt{l_@@_column_\textsl{j}_max_dim}. The dimension \texttt{l_@@_column_\textsl{j}_min_dim} is the minimal
-% $x$-value of all the cells of the column~$j$. The dimension \texttt{l_@@_column_\textsl{j}_max_dim} is the maximal
-% $x$-value of all the cells of the column~$j$.
-%
-% Since these dimensions will be computed as maximum or minimum, we initialize them to |\c_max_dim| or |-\c_max_dim|.
+% For each row $i$, we compute two dimensions
+% \texttt{l_@@_row_\textsl{i}_min_dim} and \texttt{l_@@_row_\textsl{i}_max_dim}.
+% The dimension \texttt{l_@@_row_\textsl{i}_min_dim} is the minimal 
+% $y$-value of all the cells of the row~$i$. The dimension
+% \texttt{l_@@_row_\textsl{i}_max_dim} is the maximal $y$-value of all the cells
+% of the row~$i$. 
+%
+% Similarly, for each column $j$, we compute two dimensions
+% \texttt{l_@@_column_\textsl{j}_min_dim} and
+% \texttt{l_@@_column_\textsl{j}_max_dim}. The dimension
+% \texttt{l_@@_column_\textsl{j}_min_dim} is the minimal $x$-value of all the
+% cells of the column~$j$. The dimension \texttt{l_@@_column_\textsl{j}_max_dim}
+% is the maximal $x$-value of all the cells of the column~$j$.
+%
+% Since these dimensions will be computed as maximum or minimum, we initialize
+% them to |\c_max_dim| or |-\c_max_dim|. 
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_create_extra_nodes:
-     {\begin{tikzpicture}[remember~picture,overlay]
+  {
+    \begin { tikzpicture } [ remember~picture , overlay ]
       \int_step_variable:nnnNn \l_@@_nb_first_row_int 1 \g_@@_row_int \@@_i
-          {\dim_zero_new:c {l_@@_row_\@@_i _min_dim} 
-           \dim_set_eq:cN {l_@@_row_\@@_i _min_dim} \c_max_dim
-           \dim_zero_new:c {l_@@_row_\@@_i _max_dim} 
-           \dim_set:cn {l_@@_row_\@@_i _max_dim} {-\c_max_dim}}
+        { 
+          \dim_zero_new:c { l_@@_row_\@@_i _min_dim } 
+          \dim_set_eq:cN { l_@@_row_\@@_i _min_dim } \c_max_dim
+          \dim_zero_new:c { l_@@_row_\@@_i _max_dim } 
+          \dim_set:cn { l_@@_row_\@@_i _max_dim } { - \c_max_dim }
+        }
       \int_step_variable:nnnNn 1 1 \g_@@_column_total_int \@@_j
-          {\dim_zero_new:c {l_@@_column_\@@_j _min_dim} 
-           \dim_set_eq:cN {l_@@_column_\@@_j _min_dim} \c_max_dim
-           \dim_zero_new:c {l_@@_column_\@@_j _max_dim} 
-           \dim_set:cn {l_@@_column_\@@_j _max_dim} {-\c_max_dim}}
+        {
+          \dim_zero_new:c { l_@@_column_\@@_j _min_dim } 
+          \dim_set_eq:cN { l_@@_column_\@@_j _min_dim } \c_max_dim
+          \dim_zero_new:c { l_@@_column_\@@_j _max_dim } 
+          \dim_set:cn { l_@@_column_\@@_j _max_dim } { - \c_max_dim }
+        }
 %    \end{macrocode}
 % We begin the two nested loops over the rows and the columns of the array.
 %    \begin{macrocode}
-      \int_step_variable:nnnNn \l_@@_nb_first_row_int 1 \g_@@_row_int \@@_i
-          {\int_step_variable:nnnNn 1 1 \g_@@_column_total_int \@@_j
-%    \end{macrocode}
-% Maybe the cell ($i$-$j$) is an implicit cell (that is to say a cell after implicit ampersands |&|). In this case,
-% of course, we don't update the dimensions we want to compute.
-%    \begin{macrocode}
-            {\cs_if_exist:cT {pgf@sh@ns@nm-\int_use:N \g_@@_env_int-\@@_i-\@@_j}
-%    \end{macrocode}
-% We retrieve the coordinates of the anchor |south west| of the (normal) node of the cell ($i$-$j$). They will be
-% stored in |\pgf@x| and |\pgf@y|.
-%    \begin{macrocode}
-               {\tikz@parse@node \pgfutil@firstofone 
-                           (nm-\int_use:N \g_@@_env_int-\@@_i-\@@_j.south~west)
-                \dim_set:cn {l_@@_row_\@@_i _min_dim}
-                            {\dim_min:vn {l_@@_row_\@@_i _min_dim} \pgf@y}
-                \seq_if_in:NxF \g_@@_multicolumn_cells_seq {\@@_i-\@@_j}
-                   {\dim_set:cn {l_@@_column_\@@_j _min_dim}
-                               {\dim_min:vn {l_@@_column_\@@_j _min_dim} \pgf@x}}
-%    \end{macrocode}
-% We retrieve the coordinates of the anchor |north east| of the (normal) node of the cell ($i$-$j$). They will be
-% stored in |\pgf@x| and |\pgf@y|.
-%    \begin{macrocode}
-                \tikz@parse@node \pgfutil@firstofone 
-                           (nm-\int_use:N \g_@@_env_int-\@@_i-\@@_j.north~east)
-                \dim_set:cn {l_@@_row_\@@_i _max_dim}
-                            {\dim_max:vn {l_@@_row_\@@_i _max_dim} \pgf@y}
-                \seq_if_in:NxF \g_@@_multicolumn_cells_seq {\@@_i-\@@_j}
-                   {\dim_set:cn {l_@@_column_\@@_j _max_dim}
-                               {\dim_max:vn {l_@@_column_\@@_j _max_dim} \pgf@x}}}
-          }}
-%    \end{macrocode}
-% Now, we can create the ``medium nodes''. We use a command |\@@_create_nodes:| because this command will also be used
-% for the creation of the ``large nodes'' (after changing the value of |name-suffix|).
+      \int_step_variable:nnNn \l_@@_nb_first_row_int \g_@@_row_int \@@_i
+        { 
+          \int_step_variable:nNn \g_@@_column_total_int \@@_j
+%    \end{macrocode}
+% Maybe the cell ($i$-$j$) is an implicit cell (that is to say a cell after
+% implicit ampersands |&|). In this case, of course, we don't update the
+% dimensions we want to compute. 
+%    \begin{macrocode}
+            { \cs_if_exist:cT 
+                { pgf@sh@ns@nm - \int_use:N \g_@@_env_int - \@@_i- \@@_j }
+%    \end{macrocode}
+% We retrieve the coordinates of the anchor |south west| of the (normal) node of
+% the cell ($i$-$j$). They will be stored in |\pgf@x| and |\pgf@y|.
+%    \begin{macrocode}
+                {
+                  \tikz@parse@node \pgfutil@firstofone 
+                    ( nm - \int_use:N \g_@@_env_int 
+                         - \@@_i - \@@_j .south~west )
+                  \dim_set:cn { l_@@_row_\@@_i _min_dim}
+                    { \dim_min:vn { l_@@_row _ \@@_i _min_dim } \pgf@y }  
+                  \seq_if_in:NxF \g_@@_multicolumn_cells_seq { \@@_i - \@@_j }
+                    { 
+                      \dim_set:cn { l_@@_column _ \@@_j _ min_dim}
+                        { \dim_min:vn { l_@@_column _ \@@_j _min_dim } \pgf@x }
+                    }
+%    \end{macrocode}
+% We retrieve the coordinates of the anchor |north east| of the (normal) node of
+% the cell ($i$-$j$). They will be stored in |\pgf@x| and |\pgf@y|.
+%    \begin{macrocode}
+                 \tikz@parse@node \pgfutil@firstofone 
+                   ( nm - \int_use:N \g_@@_env_int - \@@_i - \@@_j .north~east )
+                  \dim_set:cn { l_@@_row _ \@@_i _ max_dim }
+                    { \dim_max:vn { l_@@_row _ \@@_i _ max_dim } \pgf@y }
+                  \seq_if_in:NxF \g_@@_multicolumn_cells_seq { \@@_i - \@@_j }
+                    { 
+                      \dim_set:cn { l_@@_column _ \@@_j _ max_dim }
+                        { \dim_max:vn { l_@@_column _ \@@_j _max_dim } \pgf@x }
+                    } 
+                }
+            }
+        }
+%    \end{macrocode}
+% Now, we can create the ``medium nodes''. We use a command |\@@_create_nodes:|
+% because this command will also be used for the creation of the ``large nodes''
+% (after changing the value of |name-suffix|). 
 %    \begin{macrocode} 
-      \tikzset{name~suffix = -medium}
+      \tikzset { name~suffix = -medium }
       \@@_create_nodes:
 %    \end{macrocode}
 % 
 % \bigskip
-% For ``large nodes'', the eventual ``first row'' and ``last column'' (in environments like |{pNiceArrayRC}|) don't
-% interfer. That's why the loop over the rows will start at 1 and the loop over the columns will stop at
-% $|\g_@@_column_int|$ (and not |\g_@@_column_total_int|).\footnote{We recall that |\g_@@_column_total_int| is
-% equal to |\g_@@_column_int| except if there is an exterior column. In this case, |\g_@@_column_total_int| is equal
-% to |\g_@@_column_int|${}+1$.}
+% For ``large nodes'', the eventual ``first row'' and ``last column'' (in
+% environments like |{pNiceArrayRC}|) don't interfer. That's why the loop over
+% the rows will start at 1 and the loop over the columns will stop at
+% $|\g_@@_column_int|$ (and not |\g_@@_column_total_int|).\footnote{We recall
+% that |\g_@@_column_total_int| is equal to |\g_@@_column_int| except if there
+% is an exterior column. In this case, |\g_@@_column_total_int| is equal to
+% |\g_@@_column_int|${}+1$.} 
 %     \begin{macrocode}
       \int_set:Nn \l_@@_nb_first_row_int 1
 %    \end{macrocode}
-% We have to change the values of all the dimensions \texttt{l_@@_row_\textsl{i}_min_dim},
-% \texttt{l_@@_row_\textsl{i}_max_dim}, \texttt{l_@@_column_\textsl{j}_min_dim} and
-% \texttt{l_@@_column_\textsl{j}_max_dim}. 
+% We have to change the values of all the dimensions
+% \texttt{l_@@_row_\textsl{i}_min_dim}, \texttt{l_@@_row_\textsl{i}_max_dim},
+% \texttt{l_@@_column_\textsl{j}_min_dim} and
+% \texttt{l_@@_column_\textsl{j}_max_dim}.  
 %    \begin{macrocode} 
-      \int_step_variable:nnnNn 1 1 {\g_@@_row_int-1} \@@_i
-         {\dim_set:cn {l_@@_row_\@@_i _min_dim}  
-                      {(  \dim_use:c {l_@@_row_\@@_i _min_dim} 
-                        + \dim_use:c {l_@@_row_\int_eval:n{\@@_i+1}_max_dim}) / 2}
-          \dim_set_eq:cc {l_@@_row_\int_eval:n{\@@_i+1}_max_dim} 
-                         {l_@@_row_\@@_i _min_dim} }
-      \int_step_variable:nnnNn 1 1 {\g_@@_column_int-1} \@@_j
-         {\dim_set:cn {l_@@_column_\@@_j _max_dim}  
-                      {(  \dim_use:c {l_@@_column_\@@_j _max_dim} 
-                        + \dim_use:c {l_@@_column_\int_eval:n{\@@_j+1}_min_dim}) / 2}
-          \dim_set_eq:cc {l_@@_column_\int_eval:n{\@@_j+1}_min_dim} 
-                         {l_@@_column_\@@_j _max_dim} }
-      \dim_sub:cn {l_@@_column_1_min_dim} \g_@@_left_margin_dim
-      \dim_add:cn {l_@@_column_\int_use:N \g_@@_column_int _max_dim} 
-                  \g_@@_right_margin_dim
+      \int_step_variable:nnnNn 1 1 { \g_@@_row_int - 1 } \@@_i
+        { 
+          \dim_set:cn { l_@@_row _ \@@_i _ min _ dim }  
+            {
+              (  
+                \dim_use:c { l_@@_row _ \@@_i _ min _ dim } + 
+                \dim_use:c { l_@@_row _ \int_eval:n { \@@_i + 1 } _ max _ dim }
+              ) 
+              / 2
+            }
+          \dim_set_eq:cc { l_@@_row _ \int_eval:n { \@@_i + 1 } _ max _ dim } 
+            { l_@@_row_\@@_i _min_dim } 
+        }
+      \int_step_variable:nnnNn 1 1 { \g_@@_column_int - 1 } \@@_j
+        { 
+          \dim_set:cn { l_@@_column _ \@@_j _ max _ dim }  
+            { 
+              (  
+                \dim_use:c 
+                  { l_@@_column _ \@@_j _ max _ dim } + 
+                \dim_use:c 
+                  { l_@@_column _ \int_eval:n { \@@_j + 1 } _ min _ dim }
+              ) 
+              / 2
+            }
+          \dim_set_eq:cc { l_@@_column _ \int_eval:n { \@@_j + 1 } _ min _ dim }
+            { l_@@_column _ \@@_j _ max _ dim } 
+        }
+      \dim_sub:cn 
+        { l_@@_column _ 1 _ min _ dim } 
+        \g_@@_left_margin_dim
+      \dim_add:cn 
+        { l_@@_column _ \int_use:N \g_@@_column_int _ max _ dim } 
+        \g_@@_right_margin_dim
 %    \end{macrocode}
 % Now, we can actually create the ``large nodes''.
 %    \begin{macrocode}
-      \tikzset{name~suffix = -large}
+      \tikzset { name~suffix = -large }
       \@@_create_nodes:
       \end{tikzpicture}
 %    \end{macrocode}
 %
 % \medskip
-% When used once, the command |\@@_create_extra_nodes:| must become no-op (in the current TeX group). That's why we
-% put a nullification of the command.
+% When used once, the command |\@@_create_extra_nodes:| must become no-op (in
+% the current TeX group). That's why we put a nullification of the command.
 %    \begin{macrocode}
-      \cs_set:Nn \@@_create_extra_nodes: {}}
+      \cs_set:Nn \@@_create_extra_nodes: { }
+  }
 %    \end{macrocode}
 % 
 %
 % \bigskip
-% The control sequence |\@@_create_nodes:| is used twice: for the construction of the ``medium nodes'' and for the
-% construction of the ``large nodes''. The nodes are constructed with the value of all the dimensions 
-% \texttt{l_@@_row_\textsl{i}_min_dim}, \texttt{l_@@_row_\textsl{i}_max_dim}, 
-% \texttt{l_@@_column_\textsl{j}_min_dim} and \texttt{l_@@_column_\textsl{j}_max_dim}. Between the 
-% construction of the ``medium nodes'' and the ``large nodes'', the values of these dimensions are changed.
+% The control sequence |\@@_create_nodes:| is used twice: for the construction
+% of the ``medium nodes'' and for the construction of the ``large nodes''. The
+% nodes are constructed with the value of all the dimensions
+% \texttt{l_@@_row_\textsl{i}_min_dim}, \texttt{l_@@_row_\textsl{i}_max_dim},
+% \texttt{l_@@_column_\textsl{j}_min_dim} and
+% \texttt{l_@@_column_\textsl{j}_max_dim}. Between the construction of the
+% ``medium nodes'' and the ``large nodes'', the values of these dimensions are
+% changed. 
 %     \begin{macrocode}
 \cs_new_protected:Nn \@@_create_nodes:
-      {\int_step_variable:nnnNn \l_@@_nb_first_row_int 1 \g_@@_row_int \@@_i
-          {\int_step_variable:nnnNn 1 1 \g_@@_column_total_int \@@_j
-%    \end{macrocode}
-% We create two ponctual nodes for the extremities of a diagonal of the rectangular node we want to create. These
-% nodes |(@@~south~west)| and |(@@~north~east)| are not available for the user of \pkg{nicematrix}. That's why
-% their names are independent of the row and the column. In the two nested loops, they will be overwritten until the
-% last cell.
-%    \begin{macrocode}
-              {\coordinate (@@~south~west) 
-                           at (\dim_use:c {l_@@_column_\@@_j _min_dim},
-                               \dim_use:c {l_@@_row_\@@_i _min_dim}) ; 
-               \coordinate (@@~north~east) 
-                           at (\dim_use:c {l_@@_column_\@@_j _max_dim},
-                               \dim_use:c {l_@@_row_\@@_i _max_dim}) ; 
-%    \end{macrocode}
-% We can eventually draw the rectangular node for the cell (|\@@_i|-|\@@_j|). This node is created with the Tikz library
-% \pkg{fit}. Don't forget that the Tikz option |name suffix| has been set to |-medium| or |-large|.
-%    \begin{macrocode}
-               \draw node [fit = {(@@~south~west) (@@~north~east)},
-                           inner~sep=0pt,
-                           name = nm-\int_use:N \g_@@_env_int-\@@_i-\@@_j,
-                           alias = \tl_if_empty:NF \g_@@_name_tl 
-                                         {\tl_use:N \g_@@_name_tl-\@@_i-\@@_j}] 
-                          {} ; 
-              }
+  { 
+    \int_step_variable:nnnNn \l_@@_nb_first_row_int 1 \g_@@_row_int \@@_i
+      { 
+        \int_step_variable:nnnNn 1 1 \g_@@_column_total_int \@@_j
+%    \end{macrocode}
+% We create two ponctual nodes for the extremities of a diagonal of the
+% rectangular node we want to create. These nodes |(@@~south~west)| and
+% |(@@~north~east)| are not available for the user of \pkg{nicematrix}. That's
+% why their names are independent of the row and the column. In the two nested
+% loops, they will be overwritten until the last cell.
+%    \begin{macrocode}
+          {
+            \coordinate ( @@~south~west ) 
+               at ( \dim_use:c { l_@@_column_ \@@_j _min_dim } ,
+                    \dim_use:c { l_@@_row_ \@@_i _min_dim } ) ; 
+            \coordinate ( @@~north~east ) 
+               at ( \dim_use:c { l_@@_column_ \@@_j _max_dim },
+                    \dim_use:c { l_@@_row_ \@@_i _max_dim } ) ; 
+%    \end{macrocode}
+% We can eventually draw the rectangular node for the cell (|\@@_i|-|\@@_j|).
+% This node is created with the Tikz library \pkg{fit}. Don't forget that the
+% Tikz option |name suffix| has been set to |-medium| or |-large|. 
+%    \begin{macrocode}
+            \node
+              [ 
+                node~contents = { } ,
+                fit = ( @@~south~west ) ( @@~north~east )  ,
+                inner~sep = \c_zero_dim ,
+                name = nm - \int_use:N \g_@@_env_int - \@@_i - \@@_j ,
+                alias = 
+                  \str_if_empty:NF \g_@@_name_str 
+                    { \g_@@_name_str - \@@_i - \@@_j }
+              ] 
+              ; 
           }
+      }
 %    \end{macrocode}
-% Now, we create the nodes for the cells of the |\multicolumn|. We recall that we have stored in
-% |\g_@@_multicolumn_cells_seq| the list of the cells where a |\multicolumn{|$n$|}{...}{...}| with $n$>1 was issued
-% and in |\g_@@_multicolumn_sizes_seq| the correspondant values of $n$.
+% Now, we create the nodes for the cells of the |\multicolumn|. We recall that
+% we have stored in |\g_@@_multicolumn_cells_seq| the list of the cells where a
+% |\multicolumn{|$n$|}{...}{...}| with $n$>1 was issued and in
+% |\g_@@_multicolumn_sizes_seq| the correspondant values of $n$. 
 %    \begin{macrocode}
-      \@@_seq_mapthread_function:NNN \g_@@_multicolumn_cells_seq 
-                                     \g_@@_multicolumn_sizes_seq
-                                     \@@_node_for_multicolumn:nn
-      }
+    \@@_seq_mapthread_function:NNN 
+      \g_@@_multicolumn_cells_seq 
+      \g_@@_multicolumn_sizes_seq
+      \@@_node_for_multicolumn:nn
+  }
 %    \end{macrocode}
 %
 %
 % 
 %    \begin{macrocode}
-\cs_set:Npn \@@_extract_coords: #1-#2\q_stop{\cs_set:Npn \@@_i {#1} 
-                                             \cs_set:Npn \@@_j {#2}}
+\cs_new_protected:Npn \@@_extract_coords: #1 - #2 \q_stop
+  { 
+    \cs_set:Npn \@@_i { #1 } 
+    \cs_set:Npn \@@_j { #2 }
+  }
 %    \end{macrocode}
 %
-% The command |\@@_node_for_multicolumn:nn| takes two arguments. The first is the position of the cell where the
-% command |\multicolumn{|$n$|}{...}{...}| was issued in the format $i$|-|$j$ and the second is the value of~$n$ (the
-% length of the ``multi-cell'').
+% The command |\@@_node_for_multicolumn:nn| takes two arguments. The first is
+% the position of the cell where the command |\multicolumn{|$n$|}{...}{...}| was
+% issued in the format $i$|-|$j$ and the second is the value of~$n$ (the length
+% of the ``multi-cell''). 
 %    \begin{macrocode}
 \cs_new_protected:Nn \@@_node_for_multicolumn:nn
-       {\@@_extract_coords: #1\q_stop
-        \coordinate (@@~south~west) 
-                    at (\dim_use:c {l_@@_column_\@@_j _min_dim},
-                        \dim_use:c {l_@@_row_\@@_i _min_dim}) ; 
-        \coordinate (@@~north~east) 
-                    at (\dim_use:c {l_@@_column_\int_eval:n{\@@_j+#2-1}_max_dim},
-                        \dim_use:c {l_@@_row_\@@_i _max_dim}) ; 
-        \draw node [fit = {(@@~south~west) (@@~north~east)},
-                    inner~sep=0pt,
-                    name = nm-\int_use:N \g_@@_env_int-\@@_i-\@@_j,
-                    alias = \tl_if_empty:NF \g_@@_name_tl 
-                                  {\tl_use:N \g_@@_name_tl-\@@_i-\@@_j}] 
-                   {} ; 
-        }
+  { 
+    \@@_extract_coords: #1 \q_stop
+    \coordinate ( @@~south~west ) at
+      (
+        \dim_use:c { l_@@_column _ \@@_j _ min _ dim } ,
+        \dim_use:c { l_@@_row _ \@@_i _ min _ dim } 
+      ) ; 
+    \coordinate ( @@~north~east ) at
+      ( 
+        \dim_use:c { l_@@_column _ \int_eval:n { \@@_j + #2 - 1 } _ max _ dim} ,
+        \dim_use:c { l_@@_row _ \@@_i _ max _ dim } 
+      ) ; 
+    \node 
+      [ 
+        node~contents = { } ,
+        fit = ( @@~south~west ) ( @@~north~east ) ,
+        inner~sep = \c_zero_dim ,
+        name = nm - \int_use:N \g_@@_env_int - \@@_i - \@@_j ,
+        alias = 
+          \str_if_empty:NF \g_@@_name_str { \g_@@_name_str - \@@_i - \@@_j }
+      ] 
+      ; 
+  }
 %    \end{macrocode}
 %
 %
 % \subsection{We process the options}
 %
-% We process the options when the package is loaded (with |\usepackage|) but we recommend to use
-% |\NiceMatrixOptions| instead. 
+% We process the options when the package is loaded (with |\usepackage|) but we
+% recommend to use |\NiceMatrixOptions| instead. 
 %
-% We must process these options after the definition of the environment |{NiceMatrix}| because the option
-% |renew-matrix| execute the code |\cs_set_eq:NN \env@matrix \NiceMatrix|. 
+% We must process these options after the definition of the environment
+% |{NiceMatrix}| because the option |renew-matrix| execute the code
+% |\cs_set_eq:NN \env@matrix \NiceMatrix|.  
 %
-% Of course, the command |\NiceMatrix| must be defined before such an instruction is executed.
+% Of course, the command |\NiceMatrix| must be defined before such an
+% instruction is executed. 
 %    \begin{macrocode}
 \ProcessKeysOptions {NiceMatrix}
 %    \end{macrocode}
 %
 % \subsection{Code for \texttt{seq_mapthread_function:NNN}}
 %
-% In |\@@_create_nodes:| (used twice in |\@@_create_extra_nodes:| to create the ``medium nodes'' and ``large
-% nodes''), we want to use |\seq_mapthread_function:NNN| which is in \pkg{l3candidates}). For security, we define a
-% function |\@@_seq_mapthread_function:NNN|. We will delete the following code when |\seq_mapthread_function:NNN|
-% will be in \pkg{l3seq}.
+% In |\@@_create_nodes:| (used twice in |\@@_create_extra_nodes:| to create the
+% ``medium nodes'' and ``large nodes''), we want to use
+% |\seq_mapthread_function:NNN| which is in \pkg{l3candidates}). For security,
+% we define a function |\@@_seq_mapthread_function:NNN|. We will delete the
+% following code when |\seq_mapthread_function:NNN| will be in \pkg{l3seq}.
 %    \begin{macrocode}
-\cs_new:Npn \@@_seq_mapthread_function:NNN #1#2#3
-  {\group_begin:
+\cs_new:Npn \@@_seq_mapthread_function:NNN #1 #2 #3
+  { 
+   \group_begin:
 %    \end{macrocode}
 % In the group, we can use |\seq_pop:NN| safely.
 %    \begin{macrocode}
-   \int_step_inline:nnnn 1 1 {\seq_count:N #1}
-         {\seq_pop:NN #1 \l_tmpa_tl
-          \seq_pop:NN #2 \l_tmpb_tl
-          \exp_args:NVV #3 \l_tmpa_tl \l_tmpb_tl}
+   \int_step_inline:nnnn 1 1 { \seq_count:N #1 }
+     { 
+       \seq_pop:NN #1 \l_tmpa_tl
+       \seq_pop:NN #2 \l_tmpb_tl
+       \exp_args:NVV #3 \l_tmpa_tl \l_tmpb_tl
+     }
    \group_end:
   }
 %    \end{macrocode}
 %
 %    \begin{macrocode}
-\cs_set:Nn \@@_renew_matrix:
-    {\RenewDocumentEnvironment {pmatrix} {}
-         {\begin{pNiceMatrix}}
-         {\end{pNiceMatrix}}
-     \RenewDocumentEnvironment {vmatrix} {}
-         {\begin{vNiceMatrix}}
-         {\end{vNiceMatrix}}
-     \RenewDocumentEnvironment {Vmatrix} {}
-         {\begin{VNiceMatrix}}
-         {\end{VNiceMatrix}}
-     \RenewDocumentEnvironment {bmatrix} {}
-         {\begin{bNiceMatrix}}
-         {\end{bNiceMatrix}}
-     \RenewDocumentEnvironment {Bmatrix} {}
-         {\begin{BNiceMatrix}}
-         {\end{BNiceMatrix}}}
+\cs_set_protected:Npn \@@_renew_matrix:
+  { 
+    \RenewDocumentEnvironment { pmatrix } { }
+      { \pNiceMatrix } 
+      { \endpNiceMatrix }
+    \RenewDocumentEnvironment { vmatrix } { }
+      { \vNiceMatrix }
+      { \endvNiceMatrix }
+    \RenewDocumentEnvironment { Vmatrix } { }
+      { \VNiceMatrix }
+      { \endVNiceMatrix }
+    \RenewDocumentEnvironment { bmatrix } { }
+      { \bNiceMatrix }
+      { \endbNiceMatrix }
+    \RenewDocumentEnvironment { Bmatrix } { }
+      { \BNiceMatrix }
+      { \endBNiceMatrix }
+  }
 %    \end{macrocode}
 %
 % 
@@ -4154,7 +4751,8 @@ version 2005/12/01 or later.
 %
 % \subsection{Changes between versions 1.0 and 1.1}
 % 
-% The dotted lines are no longer drawn with Tikz nodes but with Tikz circles (for efficiency).
+% The dotted lines are no longer drawn with Tikz nodes but with Tikz circles
+% (for efficiency). 
 % 
 % Modification of the code which is now twice faster.
 %
@@ -4166,56 +4764,65 @@ version 2005/12/01 or later.
 %
 % New environment |{pNiceArrayC}| and its variants.
 %
-% Correction of a bug in the definition of |{BNiceMatrix}|, |{vNiceMatrix}| and |{VNiceMatrix}| (in fact, it was a
-% typo).
+% Correction of a bug in the definition of |{BNiceMatrix}|, |{vNiceMatrix}| and
+% |{VNiceMatrix}| (in fact, it was a typo).
 %
 % Options are now available locally in |{pNiceMatrix}| and its variants. 
 % 
-% The names of the options are changed. The old names were names in ``camel style''. New names are in lowercase and
-% hyphens (but backward compatibility is kept).
+% The names of the options are changed. The old names were names in ``camel
+% style''. New names are in lowercase and hyphens (but backward compatibility is
+% kept). 
 % 
 %
 % \subsection{Changes between version 1.3 and 1.4}
 % 
-% The column types |w| and |W| can now be used in the environments |{NiceArray}|, |{pNiceArrayC}| and its variants
-% with the same meaning as in the package \pkg{array}.
+% The column types |w| and |W| can now be used in the environments
+% |{NiceArray}|, |{pNiceArrayC}| and its variants with the same meaning as in
+% the package \pkg{array}. 
 % 
-% New option |columns-width| to fix the same width for all the columns of the array.
+% New option |columns-width| to fix the same width for all the columns of the
+% array. 
 % 
 %
 % \subsection{Changes between version 1.4 and 2.0}
 % 
-% The versions 1.0 to 1.4 of \pkg{nicematrix} were focused on the continuous dotted lines whereas the version 2.0 of
-% \pkg{nicematrix} provides different features to improve the typesetting of mathematical matrices.
+% The versions 1.0 to 1.4 of \pkg{nicematrix} were focused on the continuous
+% dotted lines whereas the version 2.0 of \pkg{nicematrix} provides different
+% features to improve the typesetting of mathematical matrices. 
 %
 % \subsection{Changes between version 2.0 and 2.1}
 %
-% New implementation of the environment |{pNiceArrayRC}|. With this new implementation, there is no restriction on
-% the width of the columns.
+% New implementation of the environment |{pNiceArrayRC}|. With this new
+% implementation, there is no restriction on the width of the columns.
 %
-% The package \pkg{nicematrix} no longer loads \pkg{mathtools} but only \pkg{amsmath}.
+% The package \pkg{nicematrix} no longer loads \pkg{mathtools} but only
+% \pkg{amsmath}. 
 %
 % Creation of ``medium nodes'' and ``large nodes''.
 %
 % \subsection{Changes between version 2.1 and 2.1.1}
 %
-% Small corrections: for example, the option |code-for-first-row| is now available in the command |\NiceMatrixOptions|.
+% Small corrections: for example, the option |code-for-first-row| is now
+% available in the command |\NiceMatrixOptions|. 
 %
 % Following a discussion on
-% TeX StackExchange\footnote{cf. |tex.stackexchange.com/questions/450841/tikz-externalize-and-nicematrix-package|}, 
+% TeX StackExchange\footnote{cf.
+% |tex.stackexchange.com/questions/450841/tikz-externalize-and-nicematrix-package|},  
 % Tikz externalization is now deactivated in the environments of the
-% extension \pkg{nicematrix}.\footnote{Before this version, there was an error when using \pkg{nicematrix} with
-% Tikz externalization. In any case, it's not possible to externalize the Tikz elements constructed by
-% \pkg{nicematrix} because they use the options |overlay| and |remember picture|.}
+% extension \pkg{nicematrix}.\footnote{Before this version, there was an error
+% when using \pkg{nicematrix} with Tikz externalization. In any case, it's not
+% possible to externalize the Tikz elements constructed by \pkg{nicematrix}
+% because they use the options |overlay| and |remember picture|.} 
 % 
 % \subsection{Changes between version 2.1 and 2.1.2}
 % Option |draft|: with this option, the dotted lines are not drawn (quicker).
 %
 % \subsection{Changes between version 2.1.2 and 2.1.3}
 %
-% When searching the end of a dotted line from a command like |\Cdots| issued in the ``main matrix'' (not in the
-% column |C|), the cells in the column |C| are considered as outside the matrix. That means that it's possible to
-% do the following matrix with only a |\Cdots| command (and a single |\Vdots|).
+% When searching the end of a dotted line from a command like |\Cdots| issued in
+% the ``main matrix'' (not in the column |C|), the cells in the column |C| are
+% considered as outside the matrix. That means that it's possible to do the
+% following matrix with only a |\Cdots| command (and a single |\Vdots|). 
 % \[\begin{pNiceArrayRC}{wc{5mm}Cwc{5mm}}
 % & C_j & \\
 % \mbox{\Large $0$} & \Vdots & \mbox{\Large $0$} \\
@@ -4225,13 +4832,21 @@ version 2005/12/01 or later.
 %
 % \subsection{Changes between version 2.1.3 and 2.1.4}
 %
-% Replacement of some options |O{}| in commands and environments defined with \pkg{xparse} by |!O{}| (because a
-% recent version of \pkg{xparse} introduced the specifier |!| and modified the default behaviour of the last
-% optional arguments).
+% Replacement of some options |O { }| in commands and environments defined with
+% \pkg{xparse} by |! O { }| (because a recent version of \pkg{xparse} introduced
+% the specifier |!| and modified the default behaviour of the last optional
+% arguments). 
 %
 % See |https://www.texdev.net/2018/04/21/xparse-optional-arguments-at-the-end|
 %
+% \subsection{Changes between version 2.1.4 and 2.1.5}
+%
+% Compatibility with the classes \cls{revtex4-1} and \cls{revtex4-2}.
+% 
+% Option |allow-duplicate-names|.
+%
 % \endinput
 % Local Variables:
 % TeX-fold-mode: nil
+% fill-column: 80
 % End:
diff --git a/Master/texmf-dist/tex/latex/nicematrix/nicematrix.sty b/Master/texmf-dist/tex/latex/nicematrix/nicematrix.sty
index d681eeb9ac4..dea687e5f4a 100644
--- a/Master/texmf-dist/tex/latex/nicematrix/nicematrix.sty
+++ b/Master/texmf-dist/tex/latex/nicematrix/nicematrix.sty
@@ -18,1123 +18,1481 @@
 %% and version 1.3 or later is part of all distributions of
 %% LaTeX version 2005/12/01 or later.
 %% 
-\def\myfileversion{2.1.4}
-\def\myfiledate{2019/01/28}
+\def\myfileversion{2.1.5}
+\def\myfiledate{2019/05/27}
 \RequirePackage{tikz}
 \usetikzlibrary{fit}
-\RequirePackage{expl3}[2018-01-01]
+\RequirePackage{expl3}[2019/02/15]
 \RequirePackage{l3keys2e}
 \ProvidesExplPackage
   {nicematrix}
   {\myfiledate}
   {\myfileversion}
   {Several features to improve the typesetting of mathematical matrices with TikZ}
-\bool_new:N \c__nicem_draft_bool
-\DeclareOption {draft} {\bool_set_true:N \c__nicem_draft_bool}
-\DeclareOption* {}
+\bool_new:N \c__nm_draft_bool
+\DeclareOption { draft } { \bool_set_true:N \c__nm_draft_bool }
+\DeclareOption* { }
 \ProcessOptions \relax
-\RequirePackage{array}
-\RequirePackage{amsmath}
-\RequirePackage{xparse}[2018-10-17]
-\cs_new_protected:Nn \__nicem_error:n
-        {\msg_error:nn {nicematrix} {#1}}
-\cs_new_protected:Nn \__nicem_error:nn
-        {\msg_error:nn {nicematrix} {#1} {#2}}
-\cs_new_protected:Nn \__nicem_bool_new:N
-      {\bool_if_exist:NTF #1
-         {\bool_set_false:N #1}
-         {\bool_new:N #1}}
-\ProvideDocumentCommand \iddots {}
-      {\mathinner{\mkern 1mu
-                  \raise \p@ \hbox{.}
-                  \mkern 2mu
-                  \raise 4\p@ \hbox{.}
-                  \mkern 2mu
-                  \raise 7\p@ \vbox{\kern 7pt
-                                    \hbox{.}}
-                  \mkern 1mu}}
-\int_new:N \g__nicem_env_int
-\dim_new:N \l__nicem_columns_width_dim
-\seq_new:N \g__nicem_names_seq
-\int_new:N \l__nicem_nb_first_row_int
-\int_set:Nn \l__nicem_nb_first_row_int 1
-\bool_new:N \l__nicem_exterior_column_bool
-\tl_new:N \l__nicem_pos_env_tl
-\tl_set:Nn \l__nicem_pos_env_tl c
-\bool_new:N \l__nicem_exterior_arraycolsep_bool
-\bool_new:N \l__nicem_parallelize_diags_bool
-\bool_set_true:N \l__nicem_parallelize_diags_bool
-\bool_new:N \l__nicem_nullify_dots_bool
-\bool_new:N \l__nicem_auto_columns_width_bool
-\tl_new:N \l__nicem_code_for_last_col_tl
-\tl_new:N \g__nicem_name_tl
-\tl_new:N \l__nicem_name_tl
-\bool_new:N \l__nicem_extra_nodes_bool
-\bool_new:N \g__nicem_extra_nodes_bool
-\dim_new:N \l__nicem_left_margin_dim
-\dim_new:N \l__nicem_right_margin_dim
-\dim_new:N \g__nicem_left_margin_dim
-\dim_new:N \g__nicem_right_margin_dim
-\dim_new:N \l__nicem_extra_left_margin_dim
-\dim_new:N \l__nicem_extra_right_margin_dim
-\dim_new:N \g__nicem_extra_right_margin_dim
-\keys_define:nn {NiceMatrix/NiceMatrixOptions}
-     {parallelize-diags    .bool_set:N = \l__nicem_parallelize_diags_bool,
-      parallelize-diags    .default:n  = true,
-      ParallelizeDiagonals .meta:n = parallelize-diags,
-      renew-dots        .bool_set:N = \l__nicem_renew_dots_bool,
-      renew-dots        .default:n  = true,
-      RenewDots         .meta:n = renew-dots,
-      renew-matrix      .code:n     = \__nicem_renew_matrix:,
-      renew-matrix      .value_forbidden:n = true,
-      RenewMatrix       .meta:n     = renew-matrix,
-      transparent       .meta:n     = {renew-dots,renew-matrix},
-      transparent       .value_forbidden:n = true,
-      Transparent       .meta:n     = transparent,
-      nullify-dots      .bool_set:N = \l__nicem_nullify_dots_bool ,
-      nullify-dots      .default:n  = true,
-      NullifyDots       .meta:n     = nullify-dots,
-      code-for-last-col  .tl_set:N         = \l__nicem_code_for_last_col_tl,
-      code-for-last-col  .value_required:n = true,
-      code-for-first-row   .tl_set:N   = \l__nicem_code_for_first_row_tl,
-      code-for-first-row    .value_required:n = true,
-      exterior-arraycolsep .bool_set:N = \l__nicem_exterior_arraycolsep_bool ,
-      exterior-arraycolsep .default:n  = true,
-      columns-width     .code:n    = \str_if_eq:nnTF {#1} {auto}
-                                     {\__nicem_error:n {Option~auto~for~columns-width}}
-                                     {\dim_set:Nn \l__nicem_columns_width_dim {#1}},
-      create-extra-nodes  .bool_set:N   = \l__nicem_extra_nodes_bool,
-      create-extra-nodes  .default:n    = true,
-      left-margin  .dim_set:N  = \l__nicem_left_margin_dim,
-      left-margin  .default:n  = \arraycolsep,
-      right-margin .dim_set:N  = \l__nicem_right_margin_dim,
-      right-margin  .default:n  = \arraycolsep,
-      unknown .code:n  = \__nicem_error:n {Unknown~key~for~NiceMatrixOptions}}
-\msg_new:nnnn {nicematrix}
-              {Unknown~key~for~NiceMatrixOptions}
-              {The~key~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~command~
-               \token_to_str:N \NiceMatrixOptions.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~keys,~type~H~<return>.}
-              {The~available~keys~are~(in~alphabetic~order):~
-               code-for-last-col,~
-               exterior-arraycolsep,~
-               left-margin,~
-               nullify-dots,~
-               parallelize-diags,~
-               renew-dots,~
-               renew-matrix,~
-               right-margin,~
-               and~transparent}
-\msg_new:nnn {nicematrix}
-             {Option~auto~for~columns-width}
-             {You~can't~give~the~value~"auto"~to~the~option~"columns-width"~here.~
-              If~you~go~on,~the~option~will~be~ignored.}
-\NewDocumentCommand \NiceMatrixOptions {m}
-    {\keys_set:nn {NiceMatrix/NiceMatrixOptions} {#1}}
-\keys_define:nn {NiceMatrix/NiceMatrix}
-     {parallelize-diags .bool_set:N  = \l__nicem_parallelize_diags_bool,
-      parallelize-diags .default:n   = true,
-      renew-dots        .bool_set:N  = \l__nicem_renew_dots_bool,
-      renew-dots        .default:n   = true,
-      nullify-dots      .bool_set:N  = \l__nicem_nullify_dots_bool ,
-      nullify-dots      .default:n   = true,
-      columns-width     .code:n      = \str_if_eq:nnTF {#1} {auto}
-                                           {\bool_set_true:N
-                                                \l__nicem_auto_columns_width_bool}
-                                           {\dim_set:Nn \l__nicem_columns_width_dim {#1}},
-      name    .code:n                = {\seq_if_in:NnTF \g__nicem_names_seq {#1}
-                                           {\__nicem_error:nn {Duplicate~name} {#1}}
-                                           {\seq_gput_left:Nn \g__nicem_names_seq {#1}}
-                                        \tl_set:Nn \l__nicem_name_tl {#1}},
-      name    .value_required:n      = true,
-      code-after         .tl_set:N     = \l__nicem_code_after_tl,
-      code-after         .initial:n    = \c_empty_tl,
-      code-after         .value_required:n = true,
-      create-extra-nodes  .bool_set:N   = \l__nicem_extra_nodes_bool,
-      create-extra-nodes  .default:n    = true,
-      left-margin  .dim_set:N  = \l__nicem_left_margin_dim,
-      left-margin  .default:n  = \arraycolsep,
-      right-margin .dim_set:N  = \l__nicem_right_margin_dim,
-      right-margin .default:n  = \arraycolsep,
-      extra-left-margin  .dim_set:N  = \l__nicem_extra_left_margin_dim,
-      extra-right-margin .dim_set:N  = \l__nicem_extra_right_margin_dim,
-      unknown .code:n  = \__nicem_error:n {Unknown~option~for~NiceMatrix}}
-\msg_new:nnnn {nicematrix}
-              {Unknown~option~for~NiceMatrix}
-              {The~option~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~environment~
-               \{NiceMatrix\}~and~its~variants.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~options,~type~H~<return>.}
-              {The~available~options~are~(in~alphabetic~order):~
-               code-after,~
-               columns-width,~
-               create-extra-nodes,~
-               extra-left-margin,~
-               extra-right-margin,~
-               left-margin,~
-               name,~
-               nullify-dots,~
-               parallelize-diags,~
-               renew-dots~
-               and~right-margin.}
-\msg_new:nnnn {nicematrix}
-              {Duplicate~name}
-              {The~name~"#1"~is~already~used~and~you~shouldn't~use~
-               the~same~environment~name~twice.~You~can~go~on,~but,~
-               maybe,~you~will~have~incorrect~results~especially~
-               if~you~use~"columns-width=auto".\\
-               For~a~list~of~the~names~already~used,~type~H~<return>.}
-              {The~names~already~defined~in~this~document~are:~
-               \seq_use:Nnnn~\g__nicem_names_seq~{,~} {,~} {~and~}.}
-\keys_define:nn {NiceMatrix/NiceArray}
-     {parallelize-diags    .bool_set:N = \l__nicem_parallelize_diags_bool,
-      parallelize-diags    .default:n  = true,
-      renew-dots           .bool_set:N = \l__nicem_renew_dots_bool,
-      renew-dots           .default:n  = true,
-      nullify-dots         .bool_set:N = \l__nicem_nullify_dots_bool ,
-      nullify-dots         .default:n  = true,
-      columns-width        .code:n = \str_if_eq:nnTF {#1} {auto}
-                                       {\bool_set_true:N \l__nicem_auto_columns_width_bool}
-                                       {\dim_set:Nn \l__nicem_columns_width_dim {#1}},
-      columns-width        .value_required:n = true,
-      name                 .code:n     = {\seq_if_in:NnTF \g__nicem_names_seq {#1}
-                                            {\__nicem_error:nn {Duplicate~name} {#1}}
-                                            {\seq_gput_left:Nn \g__nicem_names_seq {#1}}
-                                          \tl_set:Nn \l__nicem_name_tl {#1}},
-      name                 .value_required:n = true,
-      c                  .code:n    = \tl_set:Nn \l__nicem_pos_env_tl c,
-      t                  .code:n    = \tl_set:Nn \l__nicem_pos_env_tl t,
-      b                  .code:n    = \tl_set:Nn \l__nicem_pos_env_tl b,
-      code-after         .tl_set:N  = \l__nicem_code_after_tl,
-      code-after         .initial:n = \c_empty_tl,
-      code-after         .value_required:n = true,
-      create-extra-nodes  .bool_set:N   = \l__nicem_extra_nodes_bool,
-      create-extra-nodes  .default:n    = true,
-      left-margin  .dim_set:N  = \l__nicem_left_margin_dim,
-      left-margin  .default:n  = \arraycolsep,
-      right-margin .dim_set:N  = \l__nicem_right_margin_dim,
-      right-margin .default:n  = \arraycolsep,
-      extra-left-margin  .dim_set:N  = \l__nicem_extra_left_margin_dim,
-      extra-right-margin .dim_set:N  = \l__nicem_extra_right_margin_dim,
-      unknown .code:n  = \__nicem_error:n {Unknown~option~for~NiceArray}}
-\msg_new:nnnn {nicematrix}
-              {Unknown~option~for~NiceArray}
-              {The~option~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~environment~
-               \{NiceArray\}.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~options,~type~H~<return>.}
-              {The~available~options~are~(in~alphabetic~order):~
-               b,~
-               c,~
-               code-after,~
-               create-extra-nodes,~
-               columns-width,~
-               extra-left-margin,~
-               extra-right-margin,~
-               left-margin,~
-               name,~
-               nullify-dots,~
-               parallelize-diags,~
-               renew-dots,~
-               right-margin,~
-               and~t.}
-\cs_new_protected:Nn \__nicem_Cell:
-   {
-    \int_gincr:N \g__nicem_column_int
-    \int_compare:nNnT \g__nicem_column_int = 1
-          {\int_gincr:N \g__nicem_row_int}
-    \int_gset:Nn \g__nicem_column_total_int
-                 {\int_max:nn \g__nicem_column_total_int \g__nicem_column_int}
+\RequirePackage { array }
+\RequirePackage { amsmath }
+\RequirePackage { xparse } [ 2018-10-17 ]
+\bool_new:N \c__nm_revtex_bool
+\@ifclassloaded { revtex4-1 }
+  { \bool_set_true:N \c__nm_revtex_bool }
+  { }
+\@ifclassloaded { revtex4-2 }
+  { \bool_set_true:N \c__nm_revtex_bool }
+  { }
+\cs_new_protected:Nn \__nm_error:n { \msg_error:nn { nicematrix } { #1 } }
+\cs_new_protected:Nn \__nm_error:nn { \msg_error:nn { nicematrix } { #1 } { #2 } }
+\cs_new_protected:Npn \__nm_msg_new:nn { \msg_new:nnn { nicematrix } }
+\cs_new_protected:Npn \__nm_msg_new:nnn { \msg_new:nnnn { nicematrix } }
+\cs_new_protected:Npn \__nm_msg_redirect_name:nn
+  { \msg_redirect_name:nnn { nicematrix } }
+\ProvideDocumentCommand \iddots { }
+  {
+    \mathinner
+      { \mkern 1 mu
+        \raise \p@ \hbox { . }
+        \mkern 2 mu
+        \raise 4 \p@ \hbox { . }
+        \mkern 2 mu
+        \raise 7 \p@ \vbox { \kern 7 pt \hbox { . } } \mkern 1 mu
+      }
+  }
+\int_new:N \g__nm_env_int
+\dim_new:N \l__nm_columns_width_dim
+\seq_new:N \g__nm_names_seq
+\int_new:N \l__nm_nb_first_row_int
+\int_set:Nn \l__nm_nb_first_row_int 1
+\bool_new:N \l__nm_exterior_column_bool
+\bool_new:N \l__nm_in_NiceArray_bool
+\str_new:N \l__nm_pos_env_str
+\str_set:Nn \l__nm_pos_env_str c
+\bool_new:N \l__nm_exterior_arraycolsep_bool
+\bool_new:N \l__nm_parallelize_diags_bool
+\bool_set_true:N \l__nm_parallelize_diags_bool
+\bool_new:N \l__nm_nullify_dots_bool
+\bool_new:N \l__nm_auto_columns_width_bool
+\tl_new:N \l__nm_code_for_last_col_tl
+\str_new:N \g__nm_name_str
+\str_new:N \l__nm_name_str
+\bool_new:N \l__nm_extra_nodes_bool
+\bool_new:N \g__nm_extra_nodes_bool
+\dim_new:N \l__nm_left_margin_dim
+\dim_new:N \l__nm_right_margin_dim
+\dim_new:N \g__nm_left_margin_dim
+\dim_new:N \g__nm_right_margin_dim
+\dim_new:N \l__nm_extra_left_margin_dim
+\dim_new:N \l__nm_extra_right_margin_dim
+\dim_new:N \g__nm_extra_right_margin_dim
+\keys_define:nn { NiceMatrix / Global }
+  {
+    parallelize-diags .bool_set:N = \l__nm_parallelize_diags_bool ,
+    parallelize-diags .default:n = true ,
+    renew-dots .bool_set:N = \l__nm_renew_dots_bool ,
+    renew-dots .default:n = true ,
+    nullify-dots .bool_set:N = \l__nm_nullify_dots_bool ,
+    nullify-dots .default:n = true ,
+    create-extra-nodes .bool_set:N = \l__nm_extra_nodes_bool ,
+    create-extra-nodes .default:n = true,
+    left-margin .dim_set:N = \l__nm_left_margin_dim ,
+    left-margin .default:n = \arraycolsep ,
+    right-margin .dim_set:N = \l__nm_right_margin_dim ,
+    right-margin .default:n = \arraycolsep ,
+    extra-left-margin .dim_set:N = \l__nm_extra_left_margin_dim ,
+    extra-right-margin .dim_set:N = \l__nm_extra_right_margin_dim
+  }
+\keys_define:nn { NiceMatrix / Env }
+  {
+    columns-width .code:n =
+      \str_if_eq:nnTF { #1 } { auto }
+        { \bool_set_true:N \l__nm_auto_columns_width_bool }
+        { \dim_set:Nn \l__nm_columns_width_dim { #1 } } ,
+    columns-width .value_required:n = true ,
+    name .code:n =
+      \seq_if_in:NnTF \g__nm_names_seq { #1 }
+         { \__nm_error:nn { Duplicate~name } { #1 } }
+         { \seq_gput_left:Nn \g__nm_names_seq { #1 } }
+      \str_set:Nn \l__nm_name_str { #1 } ,
+    name .value_required:n = true ,
+    code-after .tl_set:N = \l__nm_code_after_tl ,
+    code-after .initial:n = \c_empty_tl ,
+    code-after .value_required:n = true ,
+  }
+\keys_define:nn { NiceMatrix }
+  {
+    NiceMatrixOptions .inherit:n = NiceMatrix / Global ,
+    NiceMatrix .inherit:n =
+      {
+        NiceMatrix / Global ,
+        NiceMatrix / Env
+      } ,
+    NiceArray .inherit:n =
+      {
+        NiceMatrix / Global ,
+        NiceMatrix / Env
+      } ,
+    NiceArrayC .inherit:n =
+      {
+        NiceMatrix / Global ,
+        NiceMatrix / Env
+       } ,
+    NiceArrayRC .inherit:n =
+      {
+        NiceMatrix / Global ,
+        NiceMatrix / Env
+      }
+  }
+\keys_define:nn { NiceMatrix / NiceMatrixOptions }
+  {
+    renew-matrix .code:n = \__nm_renew_matrix: ,
+    renew-matrix .value_forbidden:n = true ,
+    RenewMatrix .meta:n = renew-matrix ,
+    transparent .meta:n = { renew-dots , renew-matrix } ,
+    transparent .value_forbidden:n = true,
+    Transparent .meta:n = transparent,
+    code-for-last-col .tl_set:N = \l__nm_code_for_last_col_tl ,
+    code-for-last-col .value_required:n = true ,
+    code-for-first-row .tl_set:N = \l__nm_code_for_first_row_tl ,
+    code-for-first-row .value_required:n = true ,
+    exterior-arraycolsep .bool_set:N = \l__nm_exterior_arraycolsep_bool ,
+    exterior-arraycolsep .default:n  = true ,
+    columns-width .code:n =
+      \str_if_eq:nnTF { #1 } { auto }
+        { \__nm_error:n { Option~auto~for~columns-width } }
+        { \dim_set:Nn \l__nm_columns_width_dim { #1 } } ,
+    allow-duplicate-names .code:n =
+      \__nm_msg_redirect_name:nn { Duplicate~name } {none} ,
+    allow-duplicate-names .value_forbidden:n = true ,
+    unknown .code:n  = \__nm_error:n { Unknown~key~for~NiceMatrixOptions } }
+\__nm_msg_new:nnn { Unknown~key~for~NiceMatrixOptions }
+  {
+    The~key~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~command~
+    \token_to_str:N \NiceMatrixOptions. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~keys,~type~H~<return>.
+  }
+  {
+    The~available~keys~are~(in~alphabetic~order):~
+    allow-duplicate-names,~
+    code-for-last-col,~
+    exterior-arraycolsep,~
+    left-margin,~
+    nullify-dots,~
+    parallelize-diags,~
+    renew-dots,~
+    renew-matrix,~
+    right-margin,~
+    and~transparent
+  }
+\__nm_msg_new:nn { Option~auto~for~columns-width }
+  {
+    You~can't~give~the~value~'auto'~to~the~option~'columns-width'~here.~
+    If~you~go~on,~the~option~will~be~ignored.
+  }
+\NewDocumentCommand \NiceMatrixOptions { m }
+  { \keys_set:nn { NiceMatrix / NiceMatrixOptions } { #1 } }
+\keys_define:nn { NiceMatrix / NiceMatrix }
+  { unknown .code:n = \__nm_error:n { Unknown~option~for~NiceMatrix } }
+\__nm_msg_new:nnn { Unknown~option~for~NiceMatrix }
+  {
+    The~option~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~environment~
+    \{NiceMatrix\}~and~its~variants. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~options,~type~H~<return>.
+  }
+  {
+    The~available~options~are~(in~alphabetic~order):~
+    code-after,~
+    columns-width,~
+    create-extra-nodes,~
+    extra-left-margin,~
+    extra-right-margin,~
+    left-margin,~
+    name,~
+    nullify-dots,~
+    parallelize-diags,~
+    renew-dots~
+    and~right-margin.
+  }
+\__nm_msg_new:nnn { Duplicate~name }
+  {
+    The~name~'\l_keys_value_tl'~is~already~used~and~you~shouldn't~use~
+    the~same~environment~name~twice.~You~can~go~on,~but,~
+    maybe,~you~will~have~incorrect~results~especially~
+    if~you~use~'columns-width=auto'. \\
+    For~a~list~of~the~names~already~used,~type~H~<return>. \\
+    If~you~don't~want~to~see~this~message~again,~use~the~option~
+    'allow-duplicate-names'.
+  }
+  {
+    The~names~already~defined~in~this~document~are:~
+    \seq_use:Nnnn \g__nm_names_seq { ,~ } { ,~ } { ~and~ }.
+  }
+\keys_define:nn { NiceMatrix / NiceArray }
+  {
+    c .code:n = \str_set:Nn \l__nm_pos_env_str c ,
+    t .code:n = \str_set:Nn \l__nm_pos_env_str t ,
+    b .code:n = \str_set:Nn \l__nm_pos_env_str b ,
+    unknown .code:n = \__nm_error:n { Unknown~option~for~NiceArray }
+  }
+\__nm_msg_new:nnn { Unknown~option~for~NiceArray }
+  {
+    The~option~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~environment~
+    \{NiceArray\}. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~options,~type~H~<return>.
+  }
+  {
+    The~available~options~are~(in~alphabetic~order):~
+    b,~
+    c,~
+    code-after,~
+    create-extra-nodes,~
+    columns-width,~
+    extra-left-margin,~
+    extra-right-margin,~
+    left-margin,~
+    name,~
+    nullify-dots,~
+    parallelize-diags,~
+    renew-dots,~
+    right-margin,~
+    and~t.
+  }
+\cs_new_protected:Nn \__nm_Cell:
+  {
+    \int_gincr:N \g__nm_column_int
+    \int_compare:nNnT \g__nm_column_int = \c_one_int
+       { \int_gincr:N \g__nm_row_int }
+    \int_gset:Nn \g__nm_column_total_int
+       { \int_max:nn \g__nm_column_total_int \g__nm_column_int }
     \hbox_set:Nw \l_tmpa_box $ % $
-    \int_compare:nNnT \g__nicem_row_int = 0
-             \l__nicem_code_for_first_row_tl}
-\cs_new_protected:Nn \__nicem_end_Cell:
-   {$ % $
+    \int_compare:nNnT \g__nm_row_int = \c_zero_int
+      \l__nm_code_for_first_row_tl
+  }
+\cs_new_protected:Nn \__nm_end_Cell:
+  { $ % $
     \hbox_set_end:
-    \dim_gset:Nn \g__nicem_max_cell_width_dim
-          {\dim_max:nn \g__nicem_max_cell_width_dim {\box_wd:N \l_tmpa_box}}
-    \int_compare:nNnT \g__nicem_row_int = 0
-       {\dim_gset:Nn \g__nicem_max_dp_row_zero_dim
-            {\dim_max:nn \g__nicem_max_dp_row_zero_dim {\box_dp:N \l_tmpa_box}}
-        \dim_gset:Nn \g__nicem_max_ht_row_zero_dim
-            {\dim_max:nn \g__nicem_max_ht_row_zero_dim {\box_ht:N \l_tmpa_box}}}
-    \int_compare:nNnT \g__nicem_row_int = 1
-       {\dim_gset:Nn \g__nicem_max_ht_row_one_dim
-            {\dim_max:nn \g__nicem_max_ht_row_one_dim {\box_ht:N \l_tmpa_box}}}
-    \tikz[remember~picture, inner~sep = 0pt, minimum~width = 0pt, baseline]
-       \node [anchor = base,
-              name = nm-\int_use:N \g__nicem_env_int-
-                        \int_use:N \g__nicem_row_int-
-                        \int_use:N \g__nicem_column_int,
-              alias = \tl_if_empty:NF \l__nicem_name_tl
-                         {\tl_use:N \l__nicem_name_tl-
-                          \int_use:N \g__nicem_row_int-
-                          \int_use:N \g__nicem_column_int} ]
-       \bgroup
-       \box_use:N \l_tmpa_box
-       \egroup ;}
-\NewDocumentEnvironment {NiceMatrix} {!O{}}
-    {\keys_set:nn {NiceMatrix/NiceMatrix} {#1}
-     \tl_set:Nn \l__nicem_pos_env_tl c
-     \bool_set_false:N \l__nicem_exterior_arraycolsep_bool
-         \NiceArray{*\c@MaxMatrixCols{C}}
+    \dim_gset:Nn \g__nm_max_cell_width_dim
+      { \dim_max:nn \g__nm_max_cell_width_dim { \box_wd:N \l_tmpa_box } }
+    \int_compare:nNnT \g__nm_row_int = \c_zero_int
+      {
+        \dim_gset:Nn \g__nm_max_dp_row_zero_dim
+          { \dim_max:nn \g__nm_max_dp_row_zero_dim { \box_dp:N \l_tmpa_box } }
+        \dim_gset:Nn \g__nm_max_ht_row_zero_dim
+          { \dim_max:nn \g__nm_max_ht_row_zero_dim { \box_ht:N \l_tmpa_box } }
       }
-    {\endarray
-     \skip_horizontal:n {-\arraycolsep}
-     \skip_horizontal:n {\g__nicem_right_margin_dim + \g__nicem_extra_right_margin_dim}}
-\cs_generate_variant:Nn \dim_set:Nn {Nx}
-\msg_new:nnn {nicematrix}
-             {We~are~yet~in~an~environment~NiceArray}
-             {Environments~\{NiceArray\}~(or~\{NiceMatrix\},~etc.)~can't~be~
-              nested.~We~can~go~on,~but,~maybe,~you~will~have~errors~or~an~incorrect~
-              result.}
-\cs_new_protected:Npn \__nicem_define_dots:
-    {\cs_set_eq:NN \Ldots \__nicem_Ldots
-     \cs_set_eq:NN \Cdots \__nicem_Cdots
-     \cs_set_eq:NN \Vdots \__nicem_Vdots
-     \cs_set_eq:NN \Ddots \__nicem_Ddots
-     \cs_set_eq:NN \Iddots \__nicem_Iddots
-     \bool_if:NT \l__nicem_renew_dots_bool
-        {\cs_set_eq:NN \ldots \__nicem_Ldots
-         \cs_set_eq:NN \cdots \__nicem_Cdots
-         \cs_set_eq:NN \vdots \__nicem_Vdots
-         \cs_set_eq:NN \ddots \__nicem_Ddots
-         \cs_set_eq:NN \iddots \__nicem_Iddots
-         \cs_set_eq:NN \dots \__nicem_Ldots
-         \cs_set_eq:NN \hdotsfor \__nicem_Hdotsfor}}
-\cs_new_protected:Npn \__nicem_define_dots_to_nil:
-    {\cs_set_eq:NN \Ldots \prg_do_nothing:
-     \cs_set_eq:NN \Cdots \prg_do_nothing:
-     \cs_set_eq:NN \Vdots \prg_do_nothing:
-     \cs_set_eq:NN \Ddots \prg_do_nothing:
-     \cs_set_eq:NN \Iddots \prg_do_nothing:
-     \bool_if:NT \l__nicem_renew_dots_bool
-        {\cs_set_eq:NN \ldots \prg_do_nothing:
-         \cs_set_eq:NN \cdots \prg_do_nothing:
-         \cs_set_eq:NN \vdots \prg_do_nothing:
-         \cs_set_eq:NN \ddots \prg_do_nothing:
-         \cs_set_eq:NN \iddots \prg_do_nothing:
-         \cs_set_eq:NN \dots \prg_do_nothing:
-         \cs_set_eq:NN \hdotsfor \__nicem_Hdotsfor}}
-\NewDocumentEnvironment {NiceArray} {O{} m !O{}}
-    {\cs_if_exist:NT \__nicem_in_NiceArray:
-           {\__nicem_error:n {We~are~yet~in~an~environment~NiceArray}}
-     \cs_if_exist:NT \tikz@library@external@loaded
-        {\tikzset{external/export = false}}
-     \cs_set:Npn \__nicem_in_NiceArray: {--Void--}
-     \group_insert_after:N \__nicem_after_array:
-     \tl_gclear_new:N \g__nicem_lines_to_draw_tl
-     \int_gincr:N \g__nicem_env_int
-     \bool_if:NF \l__nicem_block_auto_columns_width_bool
-              {\dim_gzero_new:N \g__nicem_max_cell_width_dim}
-     \dim_gzero_new:N \g__nicem_max_dp_row_zero_dim
-     \dim_gzero_new:N \g__nicem_max_ht_row_zero_dim
-     \dim_gzero_new:N \g__nicem_max_ht_row_one_dim
-     \keys_set:nn {NiceMatrix/NiceArray} {#1,#3}
-     \bool_if:NT \l__nicem_auto_columns_width_bool
-         {\group_insert_after:N \__nicem_write_max_cell_width:
-          \cs_if_free:cTF {__nicem_max_cell_width_\int_use:N \g__nicem_env_int}
-                {\dim_set:Nn \l__nicem_columns_width_dim \c_zero_dim}
-                {\dim_set:Nx \l__nicem_columns_width_dim
-                     {\use:c {__nicem_max_cell_width_\int_use:N \g__nicem_env_int}}}
-          \tl_if_empty:NF \l__nicem_name_tl
-            {\cs_if_free:cF {__nicem_max_cell_width_\l__nicem_name_tl}
-                {\dim_set:Nx \l__nicem_columns_width_dim
-                     {\use:c {__nicem_max_cell_width_\l__nicem_name_tl}}}}
-         }
-     \bool_gset_eq:NN \g__nicem_extra_nodes_bool \l__nicem_extra_nodes_bool
-     \dim_gset_eq:NN \g__nicem_left_margin_dim \l__nicem_left_margin_dim
-     \dim_gset_eq:NN \g__nicem_right_margin_dim \l__nicem_right_margin_dim
-     \dim_gset_eq:NN \g__nicem_extra_right_margin_dim \l__nicem_extra_right_margin_dim
-     \tl_gset_eq:NN \g__nicem_code_after_tl \l__nicem_code_after_tl
-     \tl_gset_eq:NN \g__nicem_name_tl \l__nicem_name_tl
-     \cs_set:Npn \ialign
-          {\everycr{\noalign{\int_gzero:N \g__nicem_column_int}}
-          \tabskip = \c_zero_skip
-          \cs_set:Npn \ialign {\everycr{}
-                               \tabskip = \c_zero_skip
-                               \halign}
-          \halign}
-     \dim_compare:nNnTF \l__nicem_columns_width_dim = \c_zero_dim
-        {\newcolumntype{L}{>{\__nicem_Cell:}l<{\__nicem_end_Cell:}}
-         \newcolumntype{C}{>{\__nicem_Cell:}c<{\__nicem_end_Cell:}}
-         \newcolumntype{R}{>{\__nicem_Cell:}r<{\__nicem_end_Cell:}}}
-        {\newcolumntype{L}{wl{\dim_use:N \l__nicem_columns_width_dim}}
-         \newcolumntype{C}{wc{\dim_use:N \l__nicem_columns_width_dim}}
-         \newcolumntype{R}{wr{\dim_use:N \l__nicem_columns_width_dim}}}
-     \cs_set_eq:NN \NC@find@w \relax
-     \cs_set_eq:NN \NC@find@W \relax
-     \newcolumntype{w}[2]
-       {>{\hbox_set:Nw \l_tmpa_box
-          \__nicem_Cell:}
-        c
-        <{\__nicem_end_Cell:
-          \hbox_set_end:
-          \makebox[##2][##1]{\box_use:N \l_tmpa_box}}}
-     \newcolumntype{W}[2]
-       {>{\hbox_set:Nw \l_tmpa_box
-          \__nicem_Cell:}
+    \int_compare:nNnT \g__nm_row_int = \c_one_int
+      {
+        \dim_gset:Nn \g__nm_max_ht_row_one_dim
+          { \dim_max:nn \g__nm_max_ht_row_one_dim { \box_ht:N \l_tmpa_box } }
+      }
+    \tikz
+      [
+        remember~picture ,
+        inner~sep = \c_zero_dim ,
+        minimum~width = \c_zero_dim ,
+        baseline
+      ]
+    \node
+      [
+        anchor = base ,
+        name = nm - \int_use:N \g__nm_env_int -
+                    \int_use:N \g__nm_row_int -
+                    \int_use:N \g__nm_column_int ,
+        alias =
+          \str_if_empty:NF \l__nm_name_str
+            {
+              \l__nm_name_str -
+              \int_use:N \g__nm_row_int -
+              \int_use:N \g__nm_column_int
+            }
+      ]
+    \bgroup
+    \box_use:N \l_tmpa_box
+    \egroup ;
+  }
+\NewDocumentEnvironment { NiceMatrix } { ! O { } }
+  {
+    \keys_set:nn { NiceMatrix / NiceMatrix } { #1 }
+    \str_set:Nn \l__nm_pos_env_str c
+    \bool_set_false:N \l__nm_exterior_arraycolsep_bool
+    \NiceArray { * \c@MaxMatrixCols C }
+  }
+  {
+    \endarray
+    \skip_horizontal:n
+      { \g__nm_right_margin_dim + \g__nm_extra_right_margin_dim - \arraycolsep }
+  }
+\cs_generate_variant:Nn \dim_set:Nn { N x }
+\__nm_msg_new:nn { Yet~in~NiceArray }
+  {
+    Environments~\{NiceArray\}~(or~\{NiceMatrix\},~etc.)~can't~be~
+    nested.~We~can~go~on,~but,~maybe,~you~will~have~errors~or~an~incorrect~
+    result.
+  }
+\cs_new_protected:Npn \__nm_define_dots:
+  {
+    \cs_set_eq:NN \Ldots \__nm_Ldots
+    \cs_set_eq:NN \Cdots \__nm_Cdots
+    \cs_set_eq:NN \Vdots \__nm_Vdots
+    \cs_set_eq:NN \Ddots \__nm_Ddots
+    \cs_set_eq:NN \Iddots \__nm_Iddots
+    \bool_if:NT \l__nm_renew_dots_bool
+      {
+        \cs_set_eq:NN \ldots \__nm_Ldots
+        \cs_set_eq:NN \cdots \__nm_Cdots
+        \cs_set_eq:NN \vdots \__nm_Vdots
+        \cs_set_eq:NN \ddots \__nm_Ddots
+        \cs_set_eq:NN \iddots \__nm_Iddots
+        \cs_set_eq:NN \dots \__nm_Ldots
+        \cs_set_eq:NN \hdotsfor \__nm_Hdotsfor
+      }
+  }
+\cs_new_protected:Npn \__nm_define_dots_to_nil:
+  {
+    \cs_set_eq:NN \Ldots \prg_do_nothing:
+    \cs_set_eq:NN \Cdots \prg_do_nothing:
+    \cs_set_eq:NN \Vdots \prg_do_nothing:
+    \cs_set_eq:NN \Ddots \prg_do_nothing:
+    \cs_set_eq:NN \Iddots \prg_do_nothing:
+    \bool_if:NT \l__nm_renew_dots_bool
+      {
+        \cs_set_eq:NN \ldots \prg_do_nothing:
+        \cs_set_eq:NN \cdots \prg_do_nothing:
+        \cs_set_eq:NN \vdots \prg_do_nothing:
+        \cs_set_eq:NN \ddots \prg_do_nothing:
+        \cs_set_eq:NN \iddots \prg_do_nothing:
+        \cs_set_eq:NN \dots \prg_do_nothing:
+        \cs_set_eq:NN \hdotsfor \__nm_Hdotsfor
+      }
+  }
+\NewDocumentEnvironment { NiceArray } { O { } m ! O { } }
+  {
+    \bool_if:NT \l__nm_in_NiceArray_bool
+      { \__nm_error:n { Yet~in~NiceArray } }
+    \cs_if_exist:NT \tikz@library@external@loaded
+      { \tikzset { external / export = false } }
+    \bool_set_true:N \l__nm_in_NiceArray_bool
+    \group_insert_after:N \__nm_after_array:
+    \tl_gclear_new:N \g__nm_lines_to_draw_tl
+    \int_gincr:N \g__nm_env_int
+    \bool_if:NF \l__nm_block_auto_columns_width_bool
+      { \dim_gzero_new:N \g__nm_max_cell_width_dim }
+    \dim_gzero_new:N \g__nm_max_dp_row_zero_dim
+    \dim_gzero_new:N \g__nm_max_ht_row_zero_dim
+    \dim_gzero_new:N \g__nm_max_ht_row_one_dim
+    \keys_set:nn { NiceMatrix / NiceArray } { #1 , #3 }
+    \bool_if:NT \l__nm_auto_columns_width_bool
+      {
+        \group_insert_after:N \__nm_write_max_cell_width:
+         \cs_if_free:cTF { __nm_max_cell_width_ \int_use:N \g__nm_env_int }
+           { \dim_set:Nn \l__nm_columns_width_dim \c_zero_dim }
+           {
+             \dim_set:Nx \l__nm_columns_width_dim
+               { \use:c { __nm_max_cell_width _ \int_use:N \g__nm_env_int } }
+           }
+         \str_if_empty:NF \l__nm_name_str
+           {
+             \cs_if_free:cF { __nm_max_cell_width_ \l__nm_name_str }
+               {
+                 \dim_set:Nx \l__nm_columns_width_dim
+                   { \use:c { __nm_max_cell_width_ \l__nm_name_str } }
+               }
+           }
+      }
+    \bool_gset_eq:NN \g__nm_extra_nodes_bool \l__nm_extra_nodes_bool
+    \dim_gset_eq:NN \g__nm_left_margin_dim \l__nm_left_margin_dim
+    \dim_gset_eq:NN \g__nm_right_margin_dim \l__nm_right_margin_dim
+    \dim_gset_eq:NN \g__nm_extra_right_margin_dim \l__nm_extra_right_margin_dim
+    \tl_gset_eq:NN \g__nm_code_after_tl \l__nm_code_after_tl
+    \tl_gset_eq:NN \g__nm_name_str \l__nm_name_str
+    \cs_set:Npn \ialign
+       {
+         \everycr { \noalign { \int_gzero:N \g__nm_column_int } }
+         \tabskip = \c_zero_skip
+         \cs_set:Npn \ialign
+            {
+              \everycr { }
+              \tabskip = \c_zero_skip
+              \halign
+            }
+         \halign
+       }
+    \dim_compare:nNnTF \l__nm_columns_width_dim = \c_zero_dim
+       {
+        \newcolumntype L { > \__nm_Cell: l < \__nm_end_Cell: }
+        \newcolumntype C { > \__nm_Cell: c < \__nm_end_Cell: }
+        \newcolumntype R { > \__nm_Cell: r < \__nm_end_Cell: }
+       }
+       {
+        \newcolumntype L { w l { \dim_use:N \l__nm_columns_width_dim } }
+        \newcolumntype C { w c { \dim_use:N \l__nm_columns_width_dim } }
+        \newcolumntype R { w r { \dim_use:N \l__nm_columns_width_dim } }
+       }
+    \cs_set_eq:NN \NC@find@w \relax
+    \cs_set_eq:NN \NC@find@W \relax
+    \newcolumntype w [ 2 ]
+      {
+        > {
+            \hbox_set:Nw \l_tmpa_box
+            \__nm_Cell:}
         c
-        <{\__nicem_end_Cell:
-          \hbox_set_end:
-          \cs_set_eq:NN \hss \hfil
-          \makebox[##2][##1]{\box_use:N \l_tmpa_box}}}
-     \bool_if:NTF \c__nicem_draft_bool
-            \__nicem_define_dots_to_nil:
-            \__nicem_define_dots:
-     \cs_set_eq:NN \Hspace \__nicem_Hspace:
-     \cs_set_eq:NN \Hdotsfor \__nicem_Hdotsfor
-     \cs_set_eq:NN \multicolumn \__nicem_multicolumn:nnn
-     \seq_gclear_new:N  \g__nicem_empty_cells_seq
-     \seq_gclear_new:N \g__nicem_multicolumn_cells_seq
-     \seq_gclear_new:N \g__nicem_multicolumn_sizes_seq
-     \int_gzero_new:N \g__nicem_row_int
-     \int_gset:Nn \g__nicem_row_int {\l__nicem_nb_first_row_int - 1}
-     \int_gzero_new:N \g__nicem_column_int
-     \int_gzero_new:N \g__nicem_column_total_int
-     \cs_set_eq:NN \@ifnextchar \new@ifnextchar
-     \bool_if:NF \l__nicem_exterior_arraycolsep_bool
-         {\skip_horizontal:n {-\arraycolsep}}
-     \skip_horizontal:n {\l__nicem_left_margin_dim + \l__nicem_extra_left_margin_dim}
-     \array[\l__nicem_pos_env_tl]{#2}}
-    {\endarray
-     \bool_if:NF \l__nicem_exterior_arraycolsep_bool
-         {\skip_horizontal:n {-\arraycolsep}}
-     \skip_horizontal:n {\g__nicem_right_margin_dim + \g__nicem_extra_right_margin_dim}}
-\NewDocumentEnvironment {pNiceMatrix} {}
-   {\left(\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right)}
-\NewDocumentEnvironment {bNiceMatrix} {}
-   {\left[\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right]}
-\NewDocumentEnvironment {BNiceMatrix} {}
-   {\left\{\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right\}}
-\NewDocumentEnvironment {vNiceMatrix} {}
-   {\left\lvert\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right\rvert}
-\NewDocumentEnvironment {VNiceMatrix} {}
-   {\left\lVert\begin{NiceMatrix}}
-   {\end{NiceMatrix}\right\rVert}
-\cs_new_protected:Nn \__nicem_write_max_cell_width:
-    {\bool_if:NF \l__nicem_block_auto_columns_width_bool
-       {\iow_now:Nn \@mainaux {\ExplSyntaxOn}
-        \iow_now:Nx \@mainaux {\cs_gset:cpn
-                               {__nicem_max_cell_width_\int_use:N \g__nicem_env_int}
-                               {\dim_use:N \g__nicem_max_cell_width_dim} }
-          \iow_now:Nx \@mainaux {\cs_gset:cpn {__nicem_max_cell_width_\g__nicem_name_tl}
-                                              {\dim_use:N \g__nicem_max_cell_width_dim} }
-        \iow_now:Nn \@mainaux {\ExplSyntaxOff}}}
-\prg_set_conditional:Npnn \__nicem_if_not_empty_cell:nn #1#2 {T,TF}
-       {\cs_if_exist:cTF {pgf@sh@ns@nm-\int_use:N \g__nicem_env_int-
-                                       \int_use:N #1-
-                                       \int_use:N #2}
-          {\seq_if_in:NxTF \g__nicem_empty_cells_seq
-                           {\int_use:N #1-\int_use:N #2}
-             {\prg_return_false:}
-             {\begin{pgfpicture}
-                \tl_set:Nx \l_tmpa_tl {nm-\int_use:N \g__nicem_env_int-
-                                          \int_use:N #1-
-                                          \int_use:N #2}
-                \pgfpointanchor \l_tmpa_tl {east}
-                \dim_gset:Nn \g_tmpa_dim \pgf@x
-                \pgfpointanchor \l_tmpa_tl {west}
-                \dim_gset:Nn \g_tmpb_dim \pgf@x
-              \end{pgfpicture}
-              \dim_compare:nNnTF {\dim_abs:n {\g_tmpb_dim-\g_tmpa_dim}} < {0.5 pt}
-                    \prg_return_false:
-                    \prg_return_true:
-             }}
-          \prg_return_false:
+        < {
+            \__nm_end_Cell:
+            \hbox_set_end:
+            \makebox [ ##2 ] [ ##1 ] { \box_use:N \l_tmpa_box }
+          }
+      }
+    \newcolumntype W [ 2 ]
+      {
+        > {
+            \hbox_set:Nw \l_tmpa_box
+            \__nm_Cell:
+          }
+       c
+       < {
+           \__nm_end_Cell:
+           \hbox_set_end:
+           \cs_set_eq:NN \hss \hfil
+           \makebox [ ##2 ] [ ##1 ] { \box_use:N \l_tmpa_box }
+         }
+      }
+    \bool_if:NTF \c__nm_draft_bool
+      \__nm_define_dots_to_nil:
+      \__nm_define_dots:
+    \cs_set_eq:NN \Hspace \__nm_Hspace:
+    \cs_set_eq:NN \Hdotsfor \__nm_Hdotsfor
+    \cs_set_eq:NN \multicolumn \__nm_multicolumn:nnn
+    \seq_gclear_new:N  \g__nm_empty_cells_seq
+    \seq_gclear_new:N \g__nm_multicolumn_cells_seq
+    \seq_gclear_new:N \g__nm_multicolumn_sizes_seq
+    \int_gzero_new:N \g__nm_row_int
+    \int_gset:Nn \g__nm_row_int { \l__nm_nb_first_row_int - 1 }
+    \int_gzero_new:N \g__nm_column_int
+    \int_gzero_new:N \g__nm_column_total_int
+    \cs_set_eq:NN \@ifnextchar \new@ifnextchar
+    \bool_if:NF \l__nm_exterior_arraycolsep_bool
+      { \skip_horizontal:n { - \arraycolsep } }
+    \skip_horizontal:n { \l__nm_left_margin_dim + \l__nm_extra_left_margin_dim }
+    \bool_if:NTF \c__nm_revtex_bool
+       {
+         \cs_set_eq:NN \@acoll \@arrayacol
+         \cs_set_eq:NN \@acolr \@arrayacol
+         \cs_set_eq:NN \@acol \@arrayacol
+         \cs_set:Npn \@halignto { }
+         \@array@array
        }
-\cs_new_protected:Nn \__nicem_instruction_of_type:n
-     {\tl_gput_right:Nx \g__nicem_lines_to_draw_tl
-           {\exp_not:c {__nicem_draw_#1:nn}
-                       {\int_use:N \g__nicem_row_int}
-                       {\int_use:N \g__nicem_column_int}}}
-\cs_new_protected:Nn \__nicem_after_array:
-    {\group_begin:
-     \cs_if_exist:NT \tikz@library@external@loaded
-         {\tikzset{external/export = false}}
-     \int_gset_eq:NN \g__nicem_column_int \g__nicem_column_total_int
-     \bool_if:NT \l__nicem_exterior_column_bool {\int_gdecr:N \g__nicem_column_int}
-     \seq_gclear_new:N \g__nicem_yet_drawn_seq
-     \bool_if:NT \l__nicem_parallelize_diags_bool
-          {\int_zero_new:N \l__nicem_ddots_int
-           \int_zero_new:N \l__nicem_iddots_int
-           \dim_zero_new:N \l__nicem_delta_x_one_dim
-           \dim_zero_new:N \l__nicem_delta_y_one_dim
-           \dim_zero_new:N \l__nicem_delta_x_two_dim
-           \dim_zero_new:N \l__nicem_delta_y_two_dim}
-     \bool_if:NT \g__nicem_extra_nodes_bool \__nicem_create_extra_nodes:
-     \tl_if_empty:NF \g__nicem_lines_to_draw_tl
-           {\int_zero_new:N  \l__nicem_initial_i_int
-            \int_zero_new:N  \l__nicem_initial_j_int
-            \int_zero_new:N  \l__nicem_final_i_int
-            \int_zero_new:N  \l__nicem_final_j_int
-            \__nicem_bool_new:N \l__nicem_initial_open_bool
-            \__nicem_bool_new:N \l__nicem_final_open_bool
-            \g__nicem_lines_to_draw_tl}
-     \tl_gclear:N \g__nicem_lines_to_draw_tl
-     \tikzset{every~picture/.style = {overlay,
-                                      remember~picture,
-                                      name~prefix = nm-\int_use:N \g__nicem_env_int-}}
-     \cs_set_eq:NN \line \__nicem_line:nn
-     \g__nicem_code_after_tl
-     \group_end:}
-\cs_new_protected:Nn \__nicem_find_extremities_of_line:nnnn
-          {\int_set:Nn \l__nicem_initial_i_int {#1}
-           \int_set:Nn \l__nicem_initial_j_int {#2}
-           \int_set:Nn \l__nicem_final_i_int {#1}
-           \int_set:Nn \l__nicem_final_j_int {#2}
-           \bool_set_false:N \l__nicem_initial_open_bool
-           \bool_set_false:N \l__nicem_final_open_bool
-           \__nicem_bool_new:N \l__nicem_stop_loop_bool
-           \bool_do_until:Nn \l__nicem_stop_loop_bool
-              {\int_add:Nn \l__nicem_final_i_int {#3}
-               \int_add:Nn \l__nicem_final_j_int {#4}
-               \bool_if:nTF { \int_compare_p:nNn
-                                  \l__nicem_final_i_int < {\l__nicem_nb_first_row_int - 1}
-                           || \int_compare_p:nNn
-                                  \l__nicem_final_i_int > \g__nicem_row_int
-                           || \int_compare_p:nNn
-                                  \l__nicem_final_j_int < 1
-                           || \int_compare_p:nNn
-                                  \l__nicem_final_j_int > \g__nicem_column_total_int
-                           || \int_compare_p:nNn
-                                  \l__nicem_final_j_int > \g__nicem_column_int
-                              && \int_compare_p:nNn {#4} > 0 }
-                       {\bool_set_true:N \l__nicem_final_open_bool
-                        \int_sub:Nn \l__nicem_final_i_int {#3}
-                        \int_sub:Nn \l__nicem_final_j_int {#4}
-                        \bool_set_true:N \l__nicem_stop_loop_bool}
-                       {\__nicem_if_not_empty_cell:nnT
-                              \l__nicem_final_i_int
-                              \l__nicem_final_j_int
-                              {\bool_set_true:N \l__nicem_stop_loop_bool}}
-               }
-           \bool_set_false:N \l__nicem_stop_loop_bool
-           \bool_do_until:Nn \l__nicem_stop_loop_bool
-              {\int_sub:Nn \l__nicem_initial_i_int {#3}
-               \int_sub:Nn \l__nicem_initial_j_int {#4}
-               \bool_if:nTF
-                       {   \int_compare_p:nNn
-                               \l__nicem_initial_i_int < \l__nicem_nb_first_row_int
-                        || \int_compare_p:nNn
-                               \l__nicem_initial_i_int > \g__nicem_row_int
-                        || \int_compare_p:nNn
-                               \l__nicem_initial_j_int < 1
-                        || \int_compare_p:nNn
-                               \l__nicem_initial_j_int > \g__nicem_column_total_int}
-                       {\bool_set_true:N \l__nicem_initial_open_bool
-                        \int_add:Nn \l__nicem_initial_i_int {#3}
-                        \int_add:Nn \l__nicem_initial_j_int {#4}
-                        \bool_set_true:N \l__nicem_stop_loop_bool}
-                       {\__nicem_if_not_empty_cell:nnT
-                              \l__nicem_initial_i_int
-                              \l__nicem_initial_j_int
-                              {\bool_set_true:N \l__nicem_stop_loop_bool}}
-               }
-           \bool_if:nT {\l__nicem_initial_open_bool || \l__nicem_final_open_bool}
-                       \__nicem_create_extra_nodes: }
-\prg_set_conditional:Npnn \__nicem_if_yet_drawn: {F}
-            {\tl_set:Nx \l_tmpa_tl {\int_use:N \l__nicem_initial_i_int-
-                                    \int_use:N \l__nicem_initial_j_int-
-                                    \int_use:N \l__nicem_final_i_int-
-                                    \int_use:N \l__nicem_final_j_int}
-             \seq_if_in:NVTF \g__nicem_yet_drawn_seq \l_tmpa_tl
-              {\prg_return_true:}
-              {\seq_gput_left:NV \g__nicem_yet_drawn_seq \l_tmpa_tl
-               \prg_return_false:}}
-\cs_new_protected:Nn \__nicem_retrieve_coords:nn
-     {\dim_gzero_new:N \g__nicem_x_initial_dim
-      \dim_gzero_new:N \g__nicem_y_initial_dim
-      \dim_gzero_new:N \g__nicem_x_final_dim
-      \dim_gzero_new:N \g__nicem_y_final_dim
-      \begin{tikzpicture}[remember~picture]
+       \array
+    [ \l__nm_pos_env_str ] { #2 }
+  }
+  { \endarray
+     \bool_if:NF \l__nm_exterior_arraycolsep_bool
+       { \skip_horizontal:n { - \arraycolsep } }
+     \skip_horizontal:n
+       { \g__nm_right_margin_dim + \g__nm_extra_right_margin_dim }
+  }
+\NewDocumentEnvironment { pNiceMatrix } { }
+   { \left( \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right) }
+\NewDocumentEnvironment { bNiceMatrix } { }
+   { \left[ \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right] }
+\NewDocumentEnvironment { BNiceMatrix } { }
+   { \left\{ \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right\} }
+\NewDocumentEnvironment { vNiceMatrix } { }
+   { \left\lvert \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right\rvert }
+\NewDocumentEnvironment { VNiceMatrix } {}
+   { \left\lVert \begin{NiceMatrix} }
+   { \end{NiceMatrix} \right\rVert }
+\cs_new_protected:Nn \__nm_write_max_cell_width:
+  {
+    \bool_if:NF \l__nm_block_auto_columns_width_bool
+      {
+        \iow_now:Nn \@mainaux \ExplSyntaxOn
+        \iow_now:Nx \@mainaux
+          {
+            \cs_gset:cpn { __nm_max_cell_width_ \int_use:N \g__nm_env_int }
+              { \dim_use:N \g__nm_max_cell_width_dim }
+          }
+        \iow_now:Nx \@mainaux
+          {
+            \cs_gset:cpn { __nm_max_cell_width_ \g__nm_name_str }
+              { \dim_use:N \g__nm_max_cell_width_dim }
+          }
+        \iow_now:Nn \@mainaux \ExplSyntaxOff
+      }
+  }
+\prg_set_conditional:Npnn \__nm_if_not_empty_cell:nn #1 #2 { T , TF }
+  {
+    \cs_if_free:cTF
+      { pgf@sh@ns@nm -\int_use:N \g__nm_env_int - \int_use:N #1 - \int_use:N #2 }
+      \prg_return_false:
+      {
+        \seq_if_in:NxTF \g__nm_empty_cells_seq { \int_use:N #1 - \int_use:N #2 }
+          \prg_return_false:
+          {
+            \begin { pgfpicture }
+            \tl_set:Nx \l_tmpa_tl
+               { nm - \int_use:N \g__nm_env_int - \int_use:N #1 - \int_use:N #2 }
+            \pgfpointanchor \l_tmpa_tl { east }
+            \dim_gset:Nn \g_tmpa_dim \pgf@x
+            \pgfpointanchor \l_tmpa_tl { west }
+            \dim_gset:Nn \g_tmpb_dim \pgf@x
+            \end { pgfpicture }
+            \dim_compare:nTF
+              { \dim_abs:n { \g_tmpb_dim - \g_tmpa_dim } < 0.5 pt }
+              \prg_return_false:
+              \prg_return_true:
+          }
+      }
+  }
+\cs_new_protected:Nn \__nm_instruction_of_type:n
+  {
+    \tl_gput_right:Nx \g__nm_lines_to_draw_tl
+      {
+        \exp_not:c { __nm _ draw _ #1 : nn }
+          { \int_use:N \g__nm_row_int }
+          { \int_use:N \g__nm_column_int }
+      }
+  }
+\cs_new_protected:Nn \__nm_after_array:
+  {
+    \group_begin:
+    \cs_if_exist:NT \tikz@library@external@loaded
+      { \tikzset { external / export = false } }
+    \int_gset_eq:NN \g__nm_column_int \g__nm_column_total_int
+    \bool_if:NT \l__nm_exterior_column_bool { \int_gdecr:N \g__nm_column_int }
+    \seq_gclear_new:N \g__nm_yet_drawn_seq
+    \bool_if:NT \l__nm_parallelize_diags_bool
+      {
+        \int_zero_new:N \l__nm_ddots_int
+        \int_zero_new:N \l__nm_iddots_int
+        \dim_zero_new:N \l__nm_delta_x_one_dim
+        \dim_zero_new:N \l__nm_delta_y_one_dim
+        \dim_zero_new:N \l__nm_delta_x_two_dim
+        \dim_zero_new:N \l__nm_delta_y_two_dim
+      }
+    \bool_if:NT \g__nm_extra_nodes_bool \__nm_create_extra_nodes:
+    \tl_if_empty:NF \g__nm_lines_to_draw_tl
+      {
+        \int_zero_new:N \l__nm_initial_i_int
+        \int_zero_new:N \l__nm_initial_j_int
+        \int_zero_new:N \l__nm_final_i_int
+        \int_zero_new:N \l__nm_final_j_int
+        \bool_set_false:N \l__nm_initial_open_bool
+        \bool_set_false:N \l__nm_final_open_bool
+        \g__nm_lines_to_draw_tl
+      }
+    \tl_gclear:N \g__nm_lines_to_draw_tl
+    \tikzset
+      {
+        every~picture / .style =
+         {
+           overlay ,
+           remember~picture ,
+           name~prefix = nm - \int_use:N \g__nm_env_int -
+         }
+      }
+    \cs_set_eq:NN \line \__nm_line:nn
+    \g__nm_code_after_tl
+    \group_end:
+  }
+\cs_new_protected:Nn \__nm_find_extremities_of_line:nnnn
+  {
+    \int_set:Nn \l__nm_initial_i_int { #1 }
+    \int_set:Nn \l__nm_initial_j_int { #2 }
+    \int_set:Nn \l__nm_final_i_int { #1 }
+    \int_set:Nn \l__nm_final_j_int { #2 }
+    \bool_set_false:N \l__nm_initial_open_bool
+    \bool_set_false:N \l__nm_final_open_bool
+    \bool_set_false:N \l__nm_stop_loop_bool
+    \bool_do_until:Nn \l__nm_stop_loop_bool
+      {
+        \int_add:Nn \l__nm_final_i_int { #3 }
+        \int_add:Nn \l__nm_final_j_int { #4 }
+        \bool_if:nTF
+          {
+               \int_compare_p:nNn
+                 \l__nm_final_i_int < { \l__nm_nb_first_row_int - 1 }
+            || \int_compare_p:nNn \l__nm_final_i_int > \g__nm_row_int
+            || \int_compare_p:nNn \l__nm_final_j_int < \c_one_int
+            || \int_compare_p:nNn \l__nm_final_j_int > \g__nm_column_total_int
+            || \int_compare_p:nNn \l__nm_final_j_int > \g__nm_column_int
+               && \int_compare_p:nNn { #4 } > \c_zero_int
+          }
+          {
+            \bool_set_true:N \l__nm_final_open_bool
+            \int_sub:Nn \l__nm_final_i_int { #3 }
+            \int_sub:Nn \l__nm_final_j_int { #4 }
+            \bool_set_true:N \l__nm_stop_loop_bool
+          }
+          {
+            \__nm_if_not_empty_cell:nnT \l__nm_final_i_int \l__nm_final_j_int
+              { \bool_set_true:N \l__nm_stop_loop_bool }
+          }
+      }
+    \bool_set_false:N \l__nm_stop_loop_bool
+    \bool_do_until:Nn \l__nm_stop_loop_bool
+      {
+        \int_sub:Nn \l__nm_initial_i_int { #3 }
+        \int_sub:Nn \l__nm_initial_j_int { #4 }
+        \bool_if:nTF
+          {
+            \int_compare_p:nNn \l__nm_initial_i_int < \l__nm_nb_first_row_int
+              ||
+            \int_compare_p:nNn \l__nm_initial_i_int > \g__nm_row_int
+              ||
+            \int_compare_p:nNn \l__nm_initial_j_int < 1
+              ||
+            \int_compare_p:nNn \l__nm_initial_j_int > \g__nm_column_total_int
+          }
+          {
+            \bool_set_true:N \l__nm_initial_open_bool
+            \int_add:Nn \l__nm_initial_i_int { #3 }
+            \int_add:Nn \l__nm_initial_j_int { #4 }
+            \bool_set_true:N \l__nm_stop_loop_bool
+          }
+          {
+            \__nm_if_not_empty_cell:nnT
+              \l__nm_initial_i_int \l__nm_initial_j_int
+              { \bool_set_true:N \l__nm_stop_loop_bool }
+          }
+      }
+    \bool_if:nT { \l__nm_initial_open_bool || \l__nm_final_open_bool }
+      \__nm_create_extra_nodes:
+  }
+\prg_set_conditional:Npnn \__nm_if_yet_drawn: { F }
+  {
+    \tl_set:Nx \l_tmpa_tl
+      {
+        \int_use:N \l__nm_initial_i_int -
+        \int_use:N \l__nm_initial_j_int -
+        \int_use:N \l__nm_final_i_int -
+        \int_use:N \l__nm_final_j_int
+      }
+    \seq_if_in:NVTF \g__nm_yet_drawn_seq \l_tmpa_tl
+      \prg_return_true:
+      {
+        \seq_gput_left:NV \g__nm_yet_drawn_seq \l_tmpa_tl
+        \prg_return_false:
+      }
+  }
+\cs_new_protected:Nn \__nm_retrieve_coords:nn
+  {
+    \dim_gzero_new:N \g__nm_x_initial_dim
+    \dim_gzero_new:N \g__nm_y_initial_dim
+    \dim_gzero_new:N \g__nm_x_final_dim
+    \dim_gzero_new:N \g__nm_y_final_dim
+    \begin { tikzpicture } [ remember~picture ]
       \tikz@parse@node\pgfutil@firstofone
-             (nm-\int_use:N \g__nicem_env_int-
-                 \int_use:N \l__nicem_initial_i_int-
-                 \int_use:N \l__nicem_initial_j_int #1)
-      \dim_gset:Nn \g__nicem_x_initial_dim \pgf@x
-      \dim_gset:Nn \g__nicem_y_initial_dim \pgf@y
+        ( nm - \int_use:N \g__nm_env_int -
+               \int_use:N \l__nm_initial_i_int -
+               \int_use:N \l__nm_initial_j_int #1 )
+      \dim_gset:Nn \g__nm_x_initial_dim \pgf@x
+      \dim_gset:Nn \g__nm_y_initial_dim \pgf@y
       \tikz@parse@node\pgfutil@firstofone
-             (nm-\int_use:N \g__nicem_env_int-
-                 \int_use:N \l__nicem_final_i_int-
-                 \int_use:N \l__nicem_final_j_int #2)
-      \dim_gset:Nn \g__nicem_x_final_dim \pgf@x
-      \dim_gset:Nn \g__nicem_y_final_dim \pgf@y
-      \end{tikzpicture} }
-\cs_generate_variant:Nn \__nicem_retrieve_coords:nn {xx}
-\cs_new_protected:Nn \__nicem_draw_Ldots:nn
-      {\__nicem_find_extremities_of_line:nnnn {#1} {#2} 0 1
-       \__nicem_if_yet_drawn:F \__nicem_actually_draw_Ldots:}
-\cs_new_protected:Nn \__nicem_actually_draw_Ldots:
-          {\__nicem_retrieve_coords:xx {\bool_if:NTF \l__nicem_initial_open_bool
-                                     {-medium.base~west}
-                                     {.base~east}}
-                                  {\bool_if:NTF \l__nicem_final_open_bool
-                                     {-medium.base~east}
-                                     {.base~west}}
-           \bool_if:NT \l__nicem_initial_open_bool
-                 {\dim_gset_eq:NN \g__nicem_y_initial_dim \g__nicem_y_final_dim }
-           \bool_if:NT \l__nicem_final_open_bool
-                 {\dim_gset_eq:NN \g__nicem_y_final_dim \g__nicem_y_initial_dim }
-           \dim_gadd:Nn \g__nicem_y_initial_dim {0.53pt}
-           \dim_gadd:Nn \g__nicem_y_final_dim {0.53pt}
-           \__nicem_draw_tikz_line:}
-\cs_new_protected:Nn \__nicem_draw_Cdots:nn
-      {\__nicem_find_extremities_of_line:nnnn {#1} {#2} 0 1
-       \__nicem_if_yet_drawn:F
-            {\__nicem_retrieve_coords:xx {\bool_if:NTF \l__nicem_initial_open_bool
-                                        {-medium.mid~west}
-                                        {.mid~east}}
-                                    {\bool_if:NTF \l__nicem_final_open_bool
-                                        {-medium.mid~east}
-                                        {.mid~west}}
-             \bool_if:NT \l__nicem_initial_open_bool
-                   {\dim_gset_eq:NN \g__nicem_y_initial_dim \g__nicem_y_final_dim }
-             \bool_if:NT \l__nicem_final_open_bool
-                   {\dim_gset_eq:NN \g__nicem_y_final_dim \g__nicem_y_initial_dim }
-             \__nicem_draw_tikz_line:}}
-\cs_new_protected:Nn \__nicem_draw_Vdots:nn
-      {\__nicem_find_extremities_of_line:nnnn {#1} {#2} 1 0
-       \__nicem_if_yet_drawn:F
-       {\__nicem_retrieve_coords:xx {\bool_if:NTF \l__nicem_initial_open_bool
-                                  {-medium.north~west}
-                                  {.south~west}}
-                               {\bool_if:NTF \l__nicem_final_open_bool
-                                   {-medium.south~west}
-                                   {.north~west}}
-       \bool_set:Nn \l_tmpa_bool
-                    {\dim_compare_p:nNn \g__nicem_x_initial_dim = \g__nicem_x_final_dim}
-       \__nicem_retrieve_coords:xx {\bool_if:NTF \l__nicem_initial_open_bool
-                                 {-medium.north}
-                                 {.south}}
-                              {\bool_if:NTF \l__nicem_final_open_bool
-                                 {-medium.south}
-                                 {.north}}
-       \bool_set:Nn \l_tmpb_bool
-                    {\dim_compare_p:nNn \g__nicem_x_initial_dim = \g__nicem_x_final_dim}
-       \bool_if:NF \l_tmpb_bool
-            {\dim_gset:Nn \g__nicem_x_initial_dim
-                         {\bool_if:NTF \l_tmpa_bool \dim_min:nn \dim_max:nn
-                                       \g__nicem_x_initial_dim \g__nicem_x_final_dim}
-             \dim_gset_eq:NN \g__nicem_x_final_dim \g__nicem_x_initial_dim}
-       \__nicem_draw_tikz_line:}}
-\cs_new_protected:Nn \__nicem_draw_Ddots:nn
-   {\__nicem_find_extremities_of_line:nnnn {#1} {#2} 1 1
-    \__nicem_if_yet_drawn:F
-    {\__nicem_retrieve_coords:xx {\bool_if:NTF \l__nicem_initial_open_bool
-                                 {-medium.north~west}
-                                 {.south~east}}
-                            {\bool_if:NTF \l__nicem_final_open_bool
-                                 {-medium.south~east}
-                                 {.north~west}}
-    \bool_if:NT \l__nicem_parallelize_diags_bool
-       {\int_incr:N \l__nicem_ddots_int
-        \int_compare:nNnTF \l__nicem_ddots_int = 1
-          {\dim_set:Nn \l__nicem_delta_x_one_dim {\g__nicem_x_final_dim - \g__nicem_x_initial_dim }
-           \dim_set:Nn \l__nicem_delta_y_one_dim {\g__nicem_y_final_dim - \g__nicem_y_initial_dim }}
-          {\dim_gset:Nn \g__nicem_y_final_dim
-                  {\g__nicem_y_initial_dim +
-                      (\g__nicem_x_final_dim - \g__nicem_x_initial_dim)
-                      * \dim_ratio:nn \l__nicem_delta_y_one_dim \l__nicem_delta_x_one_dim }}}
-    \__nicem_draw_tikz_line:}}
-\cs_new_protected:Nn \__nicem_draw_Iddots:nn
-   {\__nicem_find_extremities_of_line:nnnn {#1} {#2} 1 {-1}
-    \__nicem_if_yet_drawn:F
-    {\__nicem_retrieve_coords:xx {\bool_if:NTF \l__nicem_initial_open_bool
-                              {-medium.north~east}
-                              {.south~west}}
-                           {\bool_if:NTF \l__nicem_final_open_bool
-                              {-medium.south~west}
-                              {.north~east}}
-     \bool_if:NT \l__nicem_parallelize_diags_bool
-        {\int_incr:N \l__nicem_iddots_int
-         \int_compare:nNnTF \l__nicem_iddots_int = 1
-           {\dim_set:Nn \l__nicem_delta_x_two_dim {\g__nicem_x_final_dim - \g__nicem_x_initial_dim}
-            \dim_set:Nn \l__nicem_delta_y_two_dim {\g__nicem_y_final_dim - \g__nicem_y_initial_dim}}
-           {\dim_gset:Nn \g__nicem_y_final_dim
-                   {\g__nicem_y_initial_dim +
-                       (\g__nicem_x_final_dim - \g__nicem_x_initial_dim)
-                       * \dim_ratio:nn \l__nicem_delta_y_two_dim \l__nicem_delta_x_two_dim }}}
-    \__nicem_draw_tikz_line:}}
-\cs_new_protected:Nn \__nicem_draw_tikz_line:
-                 {
-                   \dim_zero_new:N \l__nicem_l_dim
-                   \dim_set:Nn \l__nicem_l_dim
-                              { \fp_to_dim:n
-                                  { sqrt( (  \dim_use:N \g__nicem_x_final_dim
-                                            -\dim_use:N \g__nicem_x_initial_dim) ^2
-                                         +(  \dim_use:N \g__nicem_y_final_dim
-                                            -\dim_use:N \g__nicem_y_initial_dim) ^2 )}
-                              }
-                   \dim_compare:nNnF \l__nicem_l_dim = \c_zero_dim
-                     {\bool_if:NTF \l__nicem_initial_open_bool
-                       {\bool_if:NTF \l__nicem_final_open_bool
-                           {\int_set:Nn \l_tmpa_int
-                                        {\dim_ratio:nn {\l__nicem_l_dim} {0.45em}}}
-                           {\int_set:Nn \l_tmpa_int
-                                        {\dim_ratio:nn {\l__nicem_l_dim - 0.3em} {0.45em}}}}
-                       {\bool_if:NTF \l__nicem_final_open_bool
-                           {\int_set:Nn \l_tmpa_int
-                                        {\dim_ratio:nn {\l__nicem_l_dim - 0.3em} {0.45em}}}
-                           {\int_set:Nn \l_tmpa_int
-                                        {\dim_ratio:nn {\l__nicem_l_dim - 0.6em} {0.45em}}}}
-                      \dim_set:Nn \l_tmpa_dim {(\g__nicem_x_final_dim - \g__nicem_x_initial_dim)
-                                                 * \dim_ratio:nn {0.45em} \l__nicem_l_dim}
-                      \dim_set:Nn \l_tmpb_dim {(\g__nicem_y_final_dim - \g__nicem_y_initial_dim)
-                                                 * \dim_ratio:nn {0.45em} \l__nicem_l_dim}
-                      \int_set:Nn \l_tmpb_int
-                          {\bool_if:NTF \l__nicem_initial_open_bool
-                             {\bool_if:NTF \l__nicem_final_open_bool 1 0}
-                             {\bool_if:NTF \l__nicem_final_open_bool 2 1}}
-                      \dim_gadd:Nn \g__nicem_x_initial_dim
-                          {  (\g__nicem_x_final_dim - \g__nicem_x_initial_dim)
-                              * \dim_ratio:nn {\l__nicem_l_dim - 0.45 em * \l_tmpa_int}
-                                              {\l__nicem_l_dim * 2}
-                              * \l_tmpb_int}
-                      \dim_gadd:Nn \g__nicem_y_initial_dim
-                          {   (\g__nicem_y_final_dim - \g__nicem_y_initial_dim)
-                             * \dim_ratio:nn {\l__nicem_l_dim - 0.45 em * \l_tmpa_int}
-                                             {\l__nicem_l_dim * 2}
-                             * \l_tmpb_int}
-                      \begin{tikzpicture}[overlay]
-                      \int_step_inline:nnnn 0 1 \l_tmpa_int
-                         { \pgfpathcircle{\pgfpoint{\g__nicem_x_initial_dim}
-                                                   {\g__nicem_y_initial_dim}}
-                                         {0.53pt}
-                           \pgfusepath{fill}
-                           \dim_gadd:Nn \g__nicem_x_initial_dim \l_tmpa_dim
-                           \dim_gadd:Nn \g__nicem_y_initial_dim \l_tmpb_dim }
-                      \end{tikzpicture}}
-}
-\cs_set_eq:NN \__nicem_ldots \ldots
-\cs_set_eq:NN \__nicem_cdots \cdots
-\cs_set_eq:NN \__nicem_vdots \vdots
-\cs_set_eq:NN \__nicem_ddots \ddots
-\cs_set_eq:NN \__nicem_iddots \iddots
-\cs_new_protected:Nn \__nicem_add_to_empty_cells:
-    {\seq_gput_right:Nx \g__nicem_empty_cells_seq
-          {\int_use:N \g__nicem_row_int-
-           \int_use:N \g__nicem_column_int}}
-\NewDocumentCommand \__nicem_Ldots {s}
-    {\bool_if:nF {#1} {\__nicem_instruction_of_type:n {Ldots}}
-     \bool_if:NF \l__nicem_nullify_dots_bool {\phantom \__nicem_ldots}
-     \__nicem_add_to_empty_cells:}
-\NewDocumentCommand \__nicem_Cdots {s}
-    {\bool_if:nF {#1} {\__nicem_instruction_of_type:n {Cdots}}
-     \bool_if:NF \l__nicem_nullify_dots_bool {\phantom \__nicem_cdots}
-     \__nicem_add_to_empty_cells:}
-\NewDocumentCommand \__nicem_Vdots {s}
-    {\bool_if:nF {#1} {\__nicem_instruction_of_type:n {Vdots}}
-     \bool_if:NF \l__nicem_nullify_dots_bool {\phantom \__nicem_vdots}
-     \__nicem_add_to_empty_cells:}
-\NewDocumentCommand \__nicem_Ddots {s}
-    {\bool_if:nF {#1} {\__nicem_instruction_of_type:n {Ddots}}
-     \bool_if:NF \l__nicem_nullify_dots_bool {\phantom \__nicem_ddots}
-     \__nicem_add_to_empty_cells:}
-\NewDocumentCommand \__nicem_Iddots {s}
-    {\bool_if:nF {#1} {\__nicem_instruction_of_type:n {Iddots}}
-     \bool_if:NF \l__nicem_nullify_dots_bool {\phantom \__nicem_iddots}
-     \__nicem_add_to_empty_cells:}
-\cs_new_protected:Nn \__nicem_Hspace:
-  {\__nicem_add_to_empty_cells:
-   \hspace}
-\cs_set_eq:NN \__nicem_old_multicolumn \multicolumn
-\cs_new:Nn \__nicem_multicolumn:nnn
-       {\__nicem_old_multicolumn{#1}{#2}{#3}
-        \int_compare:nNnT #1 > 1
-            {\seq_gput_left:Nx \g__nicem_multicolumn_cells_seq
-                               {\int_eval:n \g__nicem_row_int -
-                                \int_use:N \g__nicem_column_int}
-             \seq_gput_left:Nn \g__nicem_multicolumn_sizes_seq {#1}}
-        \int_gadd:Nn \g__nicem_column_int {#1-1}}
-\NewDocumentCommand {\__nicem_Hdotsfor} {O{} m}
-     {\tl_gput_right:Nx \g__nicem_lines_to_draw_tl
-           {\exp_not:N \__nicem_draw_Hdotsfor:nnn
-                       {\int_use:N \g__nicem_row_int}
-                       {\int_use:N \g__nicem_column_int}
-                       {#2}}
-      \prg_replicate:nn {#2-1} {&}}
-\cs_new_protected:Nn \__nicem_draw_Hdotsfor:nnn
-       {\bool_set_false:N \l__nicem_initial_open_bool
-        \bool_set_false:N \l__nicem_final_open_bool
-        \int_set:Nn \l__nicem_initial_i_int {#1}
-        \int_set:Nn \l__nicem_final_i_int {#1}
-        \int_compare:nNnTF #2 = 1
-              {\int_set:Nn \l__nicem_initial_j_int 1
-               \bool_set_true:N \l__nicem_initial_open_bool}
-              {\int_set:Nn \l_tmpa_int {#2-1}
-               \__nicem_if_not_empty_cell:nnTF \l__nicem_initial_i_int \l_tmpa_int
-                 {\int_set:Nn \l__nicem_initial_j_int {#2-1}}
-                 {\int_set:Nn \l__nicem_initial_j_int {#2}
-                  \bool_set_true:N \l__nicem_initial_open_bool}}
-        \int_compare:nNnTF {#2+#3-1} = \g__nicem_column_int
-              {\int_set:Nn \l__nicem_final_j_int {#2+#3-1}
-               \bool_set_true:N \l__nicem_final_open_bool}
-              {\int_set:Nn \l_tmpa_int {#2+#3}
-               \__nicem_if_not_empty_cell:nnTF \l__nicem_final_i_int \l_tmpa_int
-                 {\int_set:Nn \l__nicem_final_j_int {#2+#3}}
-                 {\int_set:Nn \l__nicem_final_j_int {#2+#3-1}
-                  \bool_set_true:N \l__nicem_final_open_bool}}
-        \bool_if:nT {\l__nicem_initial_open_bool || \l__nicem_final_open_bool}
-                    \__nicem_create_extra_nodes:
-        \__nicem_actually_draw_Ldots:}
-\cs_new_protected:Nn \__nicem_line:nn
-     {\dim_zero_new:N \g__nicem_x_initial_dim
-      \dim_zero_new:N \g__nicem_y_initial_dim
-      \dim_zero_new:N \g__nicem_x_final_dim
-      \dim_zero_new:N \g__nicem_y_final_dim
-      \__nicem_bool_new:N \l__nicem_initial_open_bool
-      \__nicem_bool_new:N \l__nicem_final_open_bool
-      \begin{tikzpicture}
-         \path~(#1)~--~(#2)~node[at~start]~(i)~{}~node[at~end]~(f)~{} ;
-         \tikz@parse@node\pgfutil@firstofone (i)
-         \dim_gset:Nn \g__nicem_x_initial_dim \pgf@x
-         \dim_gset:Nn \g__nicem_y_initial_dim \pgf@y
-         \tikz@parse@node\pgfutil@firstofone (f)
-         \dim_gset:Nn \g__nicem_x_final_dim \pgf@x
-         \dim_gset:Nn \g__nicem_y_final_dim \pgf@y
-      \end{tikzpicture}
-      \__nicem_draw_tikz_line:}
-\bool_new:N \l__nicem_block_auto_columns_width_bool
-\keys_define:nn {NiceMatrix/NiceMatrixBlock}
-      {auto-columns-width .code:n =
-                           {\bool_set_true:N \l__nicem_block_auto_columns_width_bool
-                            \dim_gzero_new:N \g__nicem_max_cell_width_dim
-                            \bool_set_true:N \l__nicem_auto_columns_width_bool}}
-\NewDocumentEnvironment {NiceMatrixBlock} {!O{}}
-    {\keys_set:nn {NiceMatrix/NiceMatrixBlock} {#1}
-     \int_zero_new:N \l__nicem_first_env_block_int
-     \int_set:Nn \l__nicem_first_env_block_int {\g__nicem_env_int + 1}}
-    {\bool_if:NT \l__nicem_block_auto_columns_width_bool
-          {\iow_now:Nn \@mainaux \ExplSyntaxOn
-           \int_step_inline:nnnn \l__nicem_first_env_block_int 1 \g__nicem_env_int
-               {\iow_now:Nx \@mainaux
-                   {\cs_gset:cpn {__nicem_max_cell_width_##1}
-                                 {\dim_use:N \g__nicem_max_cell_width_dim}}}
-           \iow_now:Nn \@mainaux \ExplSyntaxOff}}
-\keys_define:nn {NiceMatrix/NiceArrayC}
-     {parallelize-diags .bool_set:N       = \l__nicem_parallelize_diags_bool,
-      parallelize-diags .default:n        = true,
-      renew-dots        .bool_set:N       = \l__nicem_renew_dots_bool,
-      renew-dots        .default:n        = true,
-      nullify-dots      .bool_set:N       = \l__nicem_nullify_dots_bool ,
-      nullify-dots      .default:n        = true,
-      code-for-last-col .tl_set:N         = \l__nicem_code_for_last_col_tl,
-      code-for-last-col .value_required:n = true,
-      columns-width     .code:n           = \str_if_eq:nnTF {#1} {auto}
-                                            {\bool_set_true:N
-                                                   \l__nicem_auto_columns_width_bool}
-                                            {\dim_set:Nn \l__nicem_columns_width_dim {#1}},
-      columns-width     .value_required:n = true,
-      name              .code:n           = {\seq_if_in:NnTF \g__nicem_names_seq {#1}
-                                                {\__nicem_error:nn {Duplicate~name} {#1}}
-                                                {\seq_gput_left:Nn \g__nicem_names_seq {#1}}
-                                             \tl_set:Nn \l__nicem_name_tl {#1}},
-      name              .value_required:n = true,
-      code-after        .tl_set:N          = \l__nicem_code_after_tl,
-      code-after        .initial:n         = \c_empty_tl,
-      code-after        .value_required:n = true,
-      create-extra-nodes  .bool_set:N   = \l__nicem_extra_nodes_bool,
-      create-extra-nodes  .default:n    = true,
-      left-margin  .dim_set:N  = \l__nicem_left_margin_dim,
-      left-margin  .default:n  = \arraycolsep,
-      right-margin .dim_set:N  = \l__nicem_right_margin_dim,
-      right-margin .default:n  = \arraycolsep,
-      extra-left-margin  .dim_set:N  = \l__nicem_extra_left_margin_dim,
-      extra-right-margin .dim_set:N  = \l__nicem_extra_right_margin_dim,
-      unknown .code:n  = \__nicem_error:n {Unknown~option~for~NiceArrayC}}
-\msg_new:nnnn {nicematrix}
-              {Unknown~option~for~NiceArrayC}
-              {The~option~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~environment~
-               \{\@currenvir\}.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~options,~type~H~<return>.}
-              {The~available~options~are~(in~alphabetic~order):~
-               code-after,~
-               code-for-last-col,~
-               columns-width,~
-               create-extra-nodes,~
-               extra-left-margin,~
-               extra-right-margin,~
-               left-margin,~
-               name,~
-               nullify-dots,~
-               parallelize-diags~
-               renew-dots~
-               and~right-margin.}
-\cs_new_protected:Nn \__nicem_NiceArrayC:n
-    {\bool_set_true:N \l__nicem_exterior_column_bool
-     \begin{NiceArray}
-             {#1
-                >{\int_gincr:N \g__nicem_column_int
-                 \int_gset:Nn \g__nicem_column_total_int
-                              {\int_max:nn \g__nicem_column_total_int \g__nicem_column_int}
-                  \hbox_set:Nw \l_tmpa_box $ % $
-                     \l__nicem_code_for_last_col_tl
-                 }
-                l
-                <{   $ % $
-                  \hbox_set_end:
-                  \dim_gset:Nn \g__nicem_width_last_col_dim
-                     {\dim_max:nn \g__nicem_width_last_col_dim
-                                  {\box_wd:N \l_tmpa_box}}
-                  \skip_horizontal:n {-2\arraycolsep}
-                  \hbox_overlap_right:n
-                       {\skip_horizontal:n
-                               { 2\arraycolsep + \l__nicem_right_margin_dim
-                                               + \l__nicem_extra_right_margin_dim}
-                        \tikz[remember~picture, inner~sep=0pt, minimum~width=0pt, baseline]
-                           \node [anchor=base,
-                                  name = nm-\int_use:N \g__nicem_env_int-
-                                            \int_use:N \g__nicem_row_int-
-                                            \int_use:N \g__nicem_column_int,
-                                  alias = \tl_if_empty:NF \l__nicem_name_tl
-                                            {\l__nicem_name_tl-
-                                             \int_use:N \g__nicem_row_int-
-                                             \int_use:N \g__nicem_column_int}]
-                                   {\box_use:N \l_tmpa_box} ; } }}}
-\NewDocumentEnvironment{NiceArrayCwithDelims} {mm O{} m !O{}}
-    {\dim_gzero_new:N \g__nicem_width_last_col_dim
-     \keys_set:nn {NiceMatrix/NiceArrayC} {#3,#5}
-     \bool_set_false:N \l__nicem_exterior_arraycolsep_bool
-     \tl_set:Nn \l__nicem_pos_env_tl c
-     \left#1
-     \__nicem_NiceArrayC:n {#4}}
-    {\end{NiceArray}
-     \right#2
-     \skip_horizontal:n \g__nicem_width_last_col_dim
-    }
-\NewDocumentEnvironment {pNiceArrayC} {}
-    {\NiceArrayCwithDelims{(}{)}}
-    {\endNiceArrayCwithDelims}
-\NewDocumentEnvironment {vNiceArrayC} {}
-    {\NiceArrayCwithDelims{|}{|}}
-    {\endNiceArrayCwithDelims}
-\NewDocumentEnvironment {VNiceArrayC} {}
-    {\NiceArrayCwithDelims{\|}{\|}}
-    {\endNiceArrayCwithDelims}
-\NewDocumentEnvironment {bNiceArrayC} {}
-    {\NiceArrayCwithDelims{[}{]}}
-    {\endNiceArrayCwithDelims}
-\NewDocumentEnvironment {BNiceArrayC} {}
-    {\NiceArrayCwithDelims{\{}{\}}}
-    {\endNiceArrayCwithDelims}
-\keys_define:nn {NiceMatrix/NiceArrayRC}
-  {parallelize-diags    .bool_set:N = \l__nicem_parallelize_diags_bool,
-   parallelize-diags    .default:n  = true,
-   renew-dots           .bool_set:N = \l__nicem_renew_dots_bool,
-   renew-dots           .default:n  = true,
-   nullify-dots         .bool_set:N = \l__nicem_nullify_dots_bool ,
-   nullify-dots         .default:n  = true,
-   code-for-first-row   .tl_set:N   = \l__nicem_code_for_first_row_tl,
-   code-for-first-row    .value_required:n = true,
-   code-for-last-col    .tl_set:N   = \l__nicem_code_for_last_col_tl,
-   code-for-last-col    .value_required:n = true,
-   columns-width        .code:n     = \str_if_eq:nnTF {#1} {auto}
-                                         {\bool_set_true:N
-                                                \l__nicem_auto_columns_width_bool}
-                                         {\dim_set:Nn \l__nicem_columns_width_dim {#1}},
-   columns-width        .value_required:n = true,
-   name                 .code:n     = {\seq_if_in:NnTF \g__nicem_names_seq {#1}
-                                          {\__nicem_error:nn {Duplicate~name} {#1}}
-                                          {\seq_gput_left:Nn \g__nicem_names_seq {#1}}
-                                       \tl_set:Nn \l__nicem_name_tl {#1}},
-   code-after           .tl_set:N    = \l__nicem_code_after_tl,
-   create-extra-nodes   .bool_set:N  = \l__nicem_extra_nodes_bool,
-   create-extra-nodes   .default:n   = true,
-   left-margin  .dim_set:N  = \l__nicem_left_margin_dim,
-   left-margin  .default:n  = \arraycolsep,
-   right-margin .dim_set:N  = \l__nicem_right_margin_dim,
-   right-margin .default:n  = \arraycolsep,
-   extra-left-margin  .dim_set:N  = \l__nicem_extra_left_margin_dim,
-   extra-right-margin .dim_set:N  = \l__nicem_extra_right_margin_dim,
-   unknown .code:n  = \__nicem_error:n {Unknown~option~for~NiceArrayRC}}
-\msg_new:nnnn {nicematrix}
-              {Unknown~option~for~NiceArrayRC}
-              {The~option~"\tl_use:N\l_keys_key_tl"~is~unknown~for~the~environment~
-               \{\@currenvir\}.\\
-               If~you~go~on,~it~will~be~ignored.\\
-               For~a~list~of~the~available~options,~type~H~<return>.}
-              {The~available~options~are~(in~alphabetic~order):~
-               code-after,~
-               code-for-last-col,~
-               code-for-first-row,~
-               columns-width,~
-               create-extra-nodes,~
-               extra-left-margin,~
-               extra-right-margin,~
-               left-margin,~
-               name,~
-               nullify-dots,~
-               parallelize-diags,~
-               renew-dots~
-               and~right-margin.}
-\NewDocumentEnvironment {NiceArrayRCwithDelims} {mm O{} m !O{}}
-    {\int_zero:N \l__nicem_nb_first_row_int
-     \dim_gzero_new:N \g__nicem_width_last_col_dim
-     \keys_set:nn {NiceMatrix/NiceArrayRC} {#3,#5}
-     \bool_set_false:N \l__nicem_exterior_arraycolsep_bool
-     \tl_set:Nn \l__nicem_pos_env_tl c
-     \box_clear_new:N \l__nicem_the_array_box
-     \hbox_set:Nw \l__nicem_the_array_box
-           $ % $
-           \__nicem_NiceArrayC:n {#4}}
-    {      \end{NiceArray}
-           $ % $
-     \hbox_set_end:
-     \dim_set:Nn \l_tmpa_dim
-            { ( \dim_max:nn {12pt}
-                            {\g__nicem_max_ht_row_one_dim + \g__nicem_max_dp_row_zero_dim})
-              + \g__nicem_max_ht_row_zero_dim
-              - \g__nicem_max_ht_row_one_dim }
-     \hbox_set:Nn \l_tmpa_box
-        {$ % $
-         \left#1
-         \vcenter {\skip_vertical:n {- \l_tmpa_dim}
-                   \box_use_drop:N \l__nicem_the_array_box}
-         \right#2
-         $ % $
-         \skip_horizontal:n \g__nicem_width_last_col_dim}
-     \box_set_ht:Nn \l_tmpa_box {\box_ht:N \l_tmpa_box + \l_tmpa_dim}
-     \box_use_drop:N \l_tmpa_box
-    }
-\NewDocumentEnvironment {pNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{(}{)}}
-     {\endNiceArrayRCwithDelims}
-\NewDocumentEnvironment {bNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{[}{]}}
-     {\endNiceArrayRCwithDelims}
-\NewDocumentEnvironment {vNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{|}{|}}
-     {\endNiceArrayRCwithDelims}
-\NewDocumentEnvironment {VNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{\|}{\|}}
-     {\endNiceArrayRCwithDelims}
-\NewDocumentEnvironment {BNiceArrayRC} {}
-     {\NiceArrayRCwithDelims{\{}{\}}}
-     {\endNiceArrayRCwithDelims}
-\cs_generate_variant:Nn \dim_min:nn {vn}
-\cs_generate_variant:Nn \dim_max:nn {vn}
-\cs_new_protected:Nn \__nicem_create_extra_nodes:
-     {\begin{tikzpicture}[remember~picture,overlay]
-      \int_step_variable:nnnNn \l__nicem_nb_first_row_int 1 \g__nicem_row_int \__nicem_i
-          {\dim_zero_new:c {l__nicem_row_\__nicem_i _min_dim}
-           \dim_set_eq:cN {l__nicem_row_\__nicem_i _min_dim} \c_max_dim
-           \dim_zero_new:c {l__nicem_row_\__nicem_i _max_dim}
-           \dim_set:cn {l__nicem_row_\__nicem_i _max_dim} {-\c_max_dim}}
-      \int_step_variable:nnnNn 1 1 \g__nicem_column_total_int \__nicem_j
-          {\dim_zero_new:c {l__nicem_column_\__nicem_j _min_dim}
-           \dim_set_eq:cN {l__nicem_column_\__nicem_j _min_dim} \c_max_dim
-           \dim_zero_new:c {l__nicem_column_\__nicem_j _max_dim}
-           \dim_set:cn {l__nicem_column_\__nicem_j _max_dim} {-\c_max_dim}}
-      \int_step_variable:nnnNn \l__nicem_nb_first_row_int 1 \g__nicem_row_int \__nicem_i
-          {\int_step_variable:nnnNn 1 1 \g__nicem_column_total_int \__nicem_j
-            {\cs_if_exist:cT {pgf@sh@ns@nm-\int_use:N \g__nicem_env_int-\__nicem_i-\__nicem_j}
-               {\tikz@parse@node \pgfutil@firstofone
-                           (nm-\int_use:N \g__nicem_env_int-\__nicem_i-\__nicem_j.south~west)
-                \dim_set:cn {l__nicem_row_\__nicem_i _min_dim}
-                            {\dim_min:vn {l__nicem_row_\__nicem_i _min_dim} \pgf@y}
-                \seq_if_in:NxF \g__nicem_multicolumn_cells_seq {\__nicem_i-\__nicem_j}
-                   {\dim_set:cn {l__nicem_column_\__nicem_j _min_dim}
-                               {\dim_min:vn {l__nicem_column_\__nicem_j _min_dim} \pgf@x}}
-                \tikz@parse@node \pgfutil@firstofone
-                           (nm-\int_use:N \g__nicem_env_int-\__nicem_i-\__nicem_j.north~east)
-                \dim_set:cn {l__nicem_row_\__nicem_i _max_dim}
-                            {\dim_max:vn {l__nicem_row_\__nicem_i _max_dim} \pgf@y}
-                \seq_if_in:NxF \g__nicem_multicolumn_cells_seq {\__nicem_i-\__nicem_j}
-                   {\dim_set:cn {l__nicem_column_\__nicem_j _max_dim}
-                               {\dim_max:vn {l__nicem_column_\__nicem_j _max_dim} \pgf@x}}}
-          }}
-      \tikzset{name~suffix = -medium}
-      \__nicem_create_nodes:
-      \int_set:Nn \l__nicem_nb_first_row_int 1
-      \int_step_variable:nnnNn 1 1 {\g__nicem_row_int-1} \__nicem_i
-         {\dim_set:cn {l__nicem_row_\__nicem_i _min_dim}
-                      {(  \dim_use:c {l__nicem_row_\__nicem_i _min_dim}
-                        + \dim_use:c {l__nicem_row_\int_eval:n{\__nicem_i+1}_max_dim}) / 2}
-          \dim_set_eq:cc {l__nicem_row_\int_eval:n{\__nicem_i+1}_max_dim}
-                         {l__nicem_row_\__nicem_i _min_dim} }
-      \int_step_variable:nnnNn 1 1 {\g__nicem_column_int-1} \__nicem_j
-         {\dim_set:cn {l__nicem_column_\__nicem_j _max_dim}
-                      {(  \dim_use:c {l__nicem_column_\__nicem_j _max_dim}
-                        + \dim_use:c {l__nicem_column_\int_eval:n{\__nicem_j+1}_min_dim}) / 2}
-          \dim_set_eq:cc {l__nicem_column_\int_eval:n{\__nicem_j+1}_min_dim}
-                         {l__nicem_column_\__nicem_j _max_dim} }
-      \dim_sub:cn {l__nicem_column_1_min_dim} \g__nicem_left_margin_dim
-      \dim_add:cn {l__nicem_column_\int_use:N \g__nicem_column_int _max_dim}
-                  \g__nicem_right_margin_dim
-      \tikzset{name~suffix = -large}
-      \__nicem_create_nodes:
-      \end{tikzpicture}
-      \cs_set:Nn \__nicem_create_extra_nodes: {}}
-\cs_new_protected:Nn \__nicem_create_nodes:
-      {\int_step_variable:nnnNn \l__nicem_nb_first_row_int 1 \g__nicem_row_int \__nicem_i
-          {\int_step_variable:nnnNn 1 1 \g__nicem_column_total_int \__nicem_j
-              {\coordinate (__nicem~south~west)
-                           at (\dim_use:c {l__nicem_column_\__nicem_j _min_dim},
-                               \dim_use:c {l__nicem_row_\__nicem_i _min_dim}) ;
-               \coordinate (__nicem~north~east)
-                           at (\dim_use:c {l__nicem_column_\__nicem_j _max_dim},
-                               \dim_use:c {l__nicem_row_\__nicem_i _max_dim}) ;
-               \draw node [fit = {(__nicem~south~west) (__nicem~north~east)},
-                           inner~sep=0pt,
-                           name = nm-\int_use:N \g__nicem_env_int-\__nicem_i-\__nicem_j,
-                           alias = \tl_if_empty:NF \g__nicem_name_tl
-                                         {\tl_use:N \g__nicem_name_tl-\__nicem_i-\__nicem_j}]
-                          {} ;
+        ( nm - \int_use:N \g__nm_env_int -
+               \int_use:N \l__nm_final_i_int -
+               \int_use:N \l__nm_final_j_int #2 )
+      \dim_gset:Nn \g__nm_x_final_dim \pgf@x
+      \dim_gset:Nn \g__nm_y_final_dim \pgf@y
+    \end { tikzpicture }
+  }
+\cs_generate_variant:Nn \__nm_retrieve_coords:nn { x x }
+\cs_new_protected:Nn \__nm_draw_Ldots:nn
+  {
+    \__nm_find_extremities_of_line:nnnn { #1 } { #2 } \c_zero_int \c_one_int
+    \__nm_if_yet_drawn:F \__nm_actually_draw_Ldots:
+  }
+\cs_new_protected:Nn \__nm_actually_draw_Ldots:
+  {
+    \__nm_retrieve_coords:xx
+      {
+        \bool_if:NTF \l__nm_initial_open_bool
+          { - medium.base~west }
+          { .base~east }
+      }
+      {
+        \bool_if:NTF \l__nm_final_open_bool
+          { - medium.base~east }
+          { . base~west }
+      }
+    \bool_if:NT \l__nm_initial_open_bool
+      { \dim_gset_eq:NN \g__nm_y_initial_dim \g__nm_y_final_dim }
+    \bool_if:NT \l__nm_final_open_bool
+      { \dim_gset_eq:NN \g__nm_y_final_dim \g__nm_y_initial_dim }
+    \dim_gadd:Nn \g__nm_y_initial_dim { 0.53 pt }
+    \dim_gadd:Nn \g__nm_y_final_dim { 0.53 pt }
+    \__nm_draw_tikz_line:
+  }
+\cs_new_protected:Nn \__nm_draw_Cdots:nn
+  {
+    \__nm_find_extremities_of_line:nnnn { #1 } { #2 } \c_zero_int \c_one_int
+    \__nm_if_yet_drawn:F
+      {
+        \__nm_retrieve_coords:xx
+          {
+            \bool_if:NTF \l__nm_initial_open_bool
+              { - medium.mid~west }
+              { .mid~east }
+          }
+          {
+            \bool_if:NTF \l__nm_final_open_bool
+            { - medium.mid~east }
+            { .mid~west }
+          }
+        \bool_if:NT \l__nm_initial_open_bool
+          { \dim_gset_eq:NN \g__nm_y_initial_dim \g__nm_y_final_dim }
+        \bool_if:NT \l__nm_final_open_bool
+          { \dim_gset_eq:NN \g__nm_y_final_dim \g__nm_y_initial_dim }
+        \__nm_draw_tikz_line:
+      }
+  }
+\cs_new_protected:Nn \__nm_draw_Vdots:nn
+  {
+    \__nm_find_extremities_of_line:nnnn { #1 } { #2 } \c_one_int \c_zero_int
+    \__nm_if_yet_drawn:F
+      { \__nm_retrieve_coords:xx
+          {
+            \bool_if:NTF \l__nm_initial_open_bool
+              { - medium.north~west }
+              { .south~west }
+          }
+          {
+            \bool_if:NTF \l__nm_final_open_bool
+              { - medium.south~west }
+              { .north~west }
+          }
+        \bool_set:Nn \l_tmpa_bool
+          { \dim_compare_p:nNn \g__nm_x_initial_dim = \g__nm_x_final_dim }
+        \__nm_retrieve_coords:xx
+          {
+            \bool_if:NTF \l__nm_initial_open_bool
+              { - medium.north }
+              { .south }
+          }
+          {
+            \bool_if:NTF \l__nm_final_open_bool
+              { - medium.south }
+              { .north }
+          }
+        \bool_set:Nn \l_tmpb_bool
+          { \dim_compare_p:nNn \g__nm_x_initial_dim = \g__nm_x_final_dim }
+        \bool_if:NF \l_tmpb_bool
+          {
+            \dim_gset:Nn \g__nm_x_initial_dim
+              {
+                \bool_if:NTF \l_tmpa_bool \dim_min:nn \dim_max:nn
+                  \g__nm_x_initial_dim \g__nm_x_final_dim
               }
+            \dim_gset_eq:NN \g__nm_x_final_dim \g__nm_x_initial_dim
           }
-      \__nicem_seq_mapthread_function:NNN \g__nicem_multicolumn_cells_seq
-                                     \g__nicem_multicolumn_sizes_seq
-                                     \__nicem_node_for_multicolumn:nn
+        \__nm_draw_tikz_line:
       }
-\cs_set:Npn \__nicem_extract_coords: #1-#2\q_stop{\cs_set:Npn \__nicem_i {#1}
-                                             \cs_set:Npn \__nicem_j {#2}}
-\cs_new_protected:Nn \__nicem_node_for_multicolumn:nn
-       {\__nicem_extract_coords: #1\q_stop
-        \coordinate (__nicem~south~west)
-                    at (\dim_use:c {l__nicem_column_\__nicem_j _min_dim},
-                        \dim_use:c {l__nicem_row_\__nicem_i _min_dim}) ;
-        \coordinate (__nicem~north~east)
-                    at (\dim_use:c {l__nicem_column_\int_eval:n{\__nicem_j+#2-1}_max_dim},
-                        \dim_use:c {l__nicem_row_\__nicem_i _max_dim}) ;
-        \draw node [fit = {(__nicem~south~west) (__nicem~north~east)},
-                    inner~sep=0pt,
-                    name = nm-\int_use:N \g__nicem_env_int-\__nicem_i-\__nicem_j,
-                    alias = \tl_if_empty:NF \g__nicem_name_tl
-                                  {\tl_use:N \g__nicem_name_tl-\__nicem_i-\__nicem_j}]
-                   {} ;
+  }
+\cs_new_protected:Nn \__nm_draw_Ddots:nn
+  {
+    \__nm_find_extremities_of_line:nnnn { #1 } { #2 } \c_one_int \c_one_int
+    \__nm_if_yet_drawn:F
+      {
+        \__nm_retrieve_coords:xx
+          {
+            \bool_if:NTF \l__nm_initial_open_bool
+              { - medium.north~west }
+              { .south~east }
+          }
+          {
+            \bool_if:NTF \l__nm_final_open_bool
+              { - medium.south~east }
+              { .north~west }
+          }
+        \bool_if:NT \l__nm_parallelize_diags_bool
+          {
+            \int_incr:N \l__nm_ddots_int
+            \int_compare:nNnTF \l__nm_ddots_int = \c_one_int
+              {
+                \dim_set:Nn \l__nm_delta_x_one_dim
+                  { \g__nm_x_final_dim - \g__nm_x_initial_dim }
+                \dim_set:Nn \l__nm_delta_y_one_dim
+                  { \g__nm_y_final_dim - \g__nm_y_initial_dim }
+              }
+              {
+                \dim_gset:Nn \g__nm_y_final_dim
+                  {
+                    \g__nm_y_initial_dim +
+                    ( \g__nm_x_final_dim - \g__nm_x_initial_dim ) *
+                    \dim_ratio:nn \l__nm_delta_y_one_dim \l__nm_delta_x_one_dim
+                  }
+              }
+          }
+        \__nm_draw_tikz_line:
+      }
+  }
+\cs_new_protected:Nn \__nm_draw_Iddots:nn
+  {
+    \__nm_find_extremities_of_line:nnnn { #1 } { #2 } 1 { -1 }
+    \__nm_if_yet_drawn:F
+      { \__nm_retrieve_coords:xx
+          {
+            \bool_if:NTF \l__nm_initial_open_bool
+              { - medium.north~east }
+              { .south~west }
+          }
+          {
+            \bool_if:NTF \l__nm_final_open_bool
+              { - medium.south~west }
+              { .north~east }
+          }
+        \bool_if:NT \l__nm_parallelize_diags_bool
+          {
+            \int_incr:N \l__nm_iddots_int
+            \int_compare:nNnTF \l__nm_iddots_int = \c_one_int
+              {
+                \dim_set:Nn \l__nm_delta_x_two_dim
+                  { \g__nm_x_final_dim - \g__nm_x_initial_dim }
+                \dim_set:Nn \l__nm_delta_y_two_dim
+                  { \g__nm_y_final_dim - \g__nm_y_initial_dim }
+              }
+              {
+                \dim_gset:Nn \g__nm_y_final_dim
+                   {
+                     \g__nm_y_initial_dim +
+                     ( \g__nm_x_final_dim - \g__nm_x_initial_dim ) *
+                     \dim_ratio:nn \l__nm_delta_y_two_dim \l__nm_delta_x_two_dim
+                   }
+              }
+          }
+        \__nm_draw_tikz_line:
+      }
+  }
+\cs_new_protected:Nn \__nm_draw_tikz_line:
+  {
+    \dim_zero_new:N \l__nm_l_dim
+    \dim_set:Nn \l__nm_l_dim
+      {
+        \fp_to_dim:n
+          {
+            sqrt
+             ( (   \dim_use:N \g__nm_x_final_dim
+                 - \dim_use:N \g__nm_x_initial_dim
+               ) ^ 2
+                  +
+               (   \dim_use:N \g__nm_y_final_dim
+                 - \dim_use:N \g__nm_y_initial_dim
+               ) ^ 2
+             )
+          }
+      }
+    \dim_compare:nNnF \l__nm_l_dim = \c_zero_dim
+      {
+        \bool_if:NTF \l__nm_initial_open_bool
+          {
+            \bool_if:NTF \l__nm_final_open_bool
+              {
+                \int_set:Nn \l_tmpa_int
+                  { \dim_ratio:nn \l__nm_l_dim { 0.45 em } }
+              }
+              {
+                \int_set:Nn \l_tmpa_int
+                  { \dim_ratio:nn { \l__nm_l_dim - 0.3 em } { 0.45 em } }
+              }
+          }
+          {
+            \bool_if:NTF \l__nm_final_open_bool
+              {
+                \int_set:Nn \l_tmpa_int
+                  { \dim_ratio:nn { \l__nm_l_dim - 0.3 em } { 0.45 em } }
+              }
+              { \int_set:Nn \l_tmpa_int
+                  { \dim_ratio:nn { \l__nm_l_dim - 0.6 em } { 0.45 em }}
+              }
+          }
+        \dim_set:Nn \l_tmpa_dim
+          {
+            ( \g__nm_x_final_dim - \g__nm_x_initial_dim ) *
+            \dim_ratio:nn { 0.45 em } \l__nm_l_dim
+          }
+        \dim_set:Nn \l_tmpb_dim
+          {
+            ( \g__nm_y_final_dim - \g__nm_y_initial_dim ) *
+            \dim_ratio:nn { 0.45 em } \l__nm_l_dim
+          }
+        \int_set:Nn \l_tmpb_int
+          {
+            \bool_if:NTF \l__nm_initial_open_bool
+              { \bool_if:NTF \l__nm_final_open_bool 1 0 }
+              { \bool_if:NTF \l__nm_final_open_bool 2 1 }
+          }
+        \dim_gadd:Nn \g__nm_x_initial_dim
+          {
+            ( \g__nm_x_final_dim - \g__nm_x_initial_dim ) *
+            \dim_ratio:nn
+              { \l__nm_l_dim - 0.45 em * \l_tmpa_int } { \l__nm_l_dim * 2 } *
+            \l_tmpb_int
+          }
+        \dim_gadd:Nn \g__nm_y_initial_dim
+          {
+            ( \g__nm_y_final_dim - \g__nm_y_initial_dim ) *
+            \dim_ratio:nn
+              { \l__nm_l_dim - 0.45 em * \l_tmpa_int }
+              { \l__nm_l_dim * 2 } *
+            \l_tmpb_int
+          }
+        \begin { tikzpicture } [ overlay ]
+          \int_step_inline:nnnn 0 1 \l_tmpa_int
+            {
+              \pgfpathcircle
+                { \pgfpoint { \g__nm_x_initial_dim } { \g__nm_y_initial_dim } }
+                { 0.53 pt }
+              \pgfusepath { fill }
+              \dim_gadd:Nn \g__nm_x_initial_dim \l_tmpa_dim
+              \dim_gadd:Nn \g__nm_y_initial_dim \l_tmpb_dim
+            }
+        \end { tikzpicture }
+      }
+  }
+\cs_set_eq:NN \__nm_ldots \ldots
+\cs_set_eq:NN \__nm_cdots \cdots
+\cs_set_eq:NN \__nm_vdots \vdots
+\cs_set_eq:NN \__nm_ddots \ddots
+\cs_set_eq:NN \__nm_iddots \iddots
+\cs_new_protected:Nn \__nm_add_to_empty_cells:
+  {
+    \seq_gput_right:Nx \g__nm_empty_cells_seq
+      { \int_use:N \g__nm_row_int - \int_use:N \g__nm_column_int }
+  }
+\NewDocumentCommand \__nm_Ldots { s }
+  {
+    \bool_if:nF { #1 } { \__nm_instruction_of_type:n { Ldots } }
+    \bool_if:NF \l__nm_nullify_dots_bool { \phantom \__nm_ldots }
+    \__nm_add_to_empty_cells:
+  }
+\NewDocumentCommand \__nm_Cdots { s }
+  {
+    \bool_if:nF { #1 } { \__nm_instruction_of_type:n { Cdots } }
+    \bool_if:NF \l__nm_nullify_dots_bool { \phantom \__nm_cdots }
+    \__nm_add_to_empty_cells:
+  }
+\NewDocumentCommand \__nm_Vdots { s }
+  {
+    \bool_if:nF { #1 } { \__nm_instruction_of_type:n { Vdots } }
+    \bool_if:NF \l__nm_nullify_dots_bool { \phantom \__nm_vdots }
+    \__nm_add_to_empty_cells:
+  }
+\NewDocumentCommand \__nm_Ddots { s }
+  {
+    \bool_if:nF { #1 } { \__nm_instruction_of_type:n { Ddots } }
+    \bool_if:NF \l__nm_nullify_dots_bool { \phantom \__nm_ddots }
+    \__nm_add_to_empty_cells:
+  }
+\NewDocumentCommand \__nm_Iddots { s }
+  {
+    \bool_if:nF { #1 } { \__nm_instruction_of_type:n { Iddots } }
+    \bool_if:NF \l__nm_nullify_dots_bool { \phantom \__nm_iddots }
+    \__nm_add_to_empty_cells:
+  }
+\cs_new_protected:Nn \__nm_Hspace:
+  {
+   \__nm_add_to_empty_cells:
+   \hspace
+  }
+\cs_set_eq:NN \__nm_old_multicolumn \multicolumn
+\cs_new:Nn \__nm_multicolumn:nnn
+  {
+    \__nm_old_multicolumn { #1 } { #2 } { #3 }
+    \int_compare:nNnT #1 > 1
+      {
+        \seq_gput_left:Nx \g__nm_multicolumn_cells_seq
+          { \int_eval:n \g__nm_row_int - \int_use:N \g__nm_column_int }
+        \seq_gput_left:Nn \g__nm_multicolumn_sizes_seq { #1 }
+      }
+    \int_gadd:Nn \g__nm_column_int { #1 - 1 }
+  }
+\NewDocumentCommand \__nm_Hdotsfor { O { } m }
+  {
+    \tl_gput_right:Nx \g__nm_lines_to_draw_tl
+      {
+        \exp_not:N \__nm_draw_Hdotsfor:nnn
+          { \int_use:N \g__nm_row_int }
+          { \int_use:N \g__nm_column_int }
+          { #2 }
+      }
+    \prg_replicate:nn { #2 - 1 } { & }
+  }
+\cs_new_protected:Nn \__nm_draw_Hdotsfor:nnn
+  {
+    \bool_set_false:N \l__nm_initial_open_bool
+    \bool_set_false:N \l__nm_final_open_bool
+    \int_set:Nn \l__nm_initial_i_int { #1 }
+    \int_set:Nn \l__nm_final_i_int { #1 }
+    \int_compare:nNnTF #2 = 1
+      {
+        \int_set:Nn \l__nm_initial_j_int 1
+        \bool_set_true:N \l__nm_initial_open_bool
+      }
+      {
+        \int_set:Nn \l_tmpa_int { #2 - 1 }
+        \__nm_if_not_empty_cell:nnTF \l__nm_initial_i_int \l_tmpa_int
+          { \int_set:Nn \l__nm_initial_j_int { #2 - 1 } }
+          {
+            \int_set:Nn \l__nm_initial_j_int {#2}
+            \bool_set_true:N \l__nm_initial_open_bool
+          }
+      }
+    \int_compare:nNnTF { #2 + #3 -1 } = \g__nm_column_int
+      {
+        \int_set:Nn \l__nm_final_j_int { #2 + #3 - 1 }
+        \bool_set_true:N \l__nm_final_open_bool
+      }
+      {
+        \int_set:Nn \l_tmpa_int { #2 + #3 }
+        \__nm_if_not_empty_cell:nnTF \l__nm_final_i_int \l_tmpa_int
+          { \int_set:Nn \l__nm_final_j_int { #2 + #3 } }
+          {
+            \int_set:Nn \l__nm_final_j_int { #2 + #3 - 1 }
+            \bool_set_true:N \l__nm_final_open_bool
+          }
+      }
+    \bool_if:nT { \l__nm_initial_open_bool || \l__nm_final_open_bool }
+      \__nm_create_extra_nodes:
+    \__nm_actually_draw_Ldots:
+  }
+\cs_new_protected:Nn \__nm_line:nn
+  {
+    \dim_zero_new:N \g__nm_x_initial_dim
+    \dim_zero_new:N \g__nm_y_initial_dim
+    \dim_zero_new:N \g__nm_x_final_dim
+    \dim_zero_new:N \g__nm_y_final_dim
+    \bool_set_false:N \l__nm_initial_open_bool
+    \bool_set_false:N \l__nm_final_open_bool
+    \begin { tikzpicture }
+       \path~(#1)~--~(#2)~node[at~start]~(i)~{}~node[at~end]~(f)~{} ;
+       \tikz@parse@node \pgfutil@firstofone ( i )
+       \dim_gset:Nn \g__nm_x_initial_dim \pgf@x
+       \dim_gset:Nn \g__nm_y_initial_dim \pgf@y
+       \tikz@parse@node \pgfutil@firstofone ( f )
+       \dim_gset:Nn \g__nm_x_final_dim \pgf@x
+       \dim_gset:Nn \g__nm_y_final_dim \pgf@y
+    \end { tikzpicture }
+    \__nm_draw_tikz_line:
+  }
+\bool_new:N \l__nm_block_auto_columns_width_bool
+\keys_define:nn { NiceMatrix / NiceMatrixBlock }
+  {
+    auto-columns-width .code:n =
+      {
+        \bool_set_true:N \l__nm_block_auto_columns_width_bool
+        \dim_gzero_new:N \g__nm_max_cell_width_dim
+        \bool_set_true:N \l__nm_auto_columns_width_bool
+      }
+  }
+\NewDocumentEnvironment { NiceMatrixBlock } { ! O { } }
+  {
+    \keys_set:nn { NiceMatrix / NiceMatrixBlock } { #1 }
+    \int_zero_new:N \l__nm_first_env_block_int
+    \int_set:Nn \l__nm_first_env_block_int { \g__nm_env_int + 1 }
+  }
+  {
+    \bool_if:NT \l__nm_block_auto_columns_width_bool
+      {
+        \iow_now:Nn \@mainaux \ExplSyntaxOn
+        \int_step_inline:nnnn \l__nm_first_env_block_int 1 \g__nm_env_int
+          {
+            \iow_now:Nx \@mainaux
+              {
+                \cs_gset:cpn { __nm _ max _ cell _ width _ ##1 }
+                  { \dim_use:N \g__nm_max_cell_width_dim }
+              }
+          }
+        \iow_now:Nn \@mainaux \ExplSyntaxOff
+      }
+  }
+\keys_define:nn { NiceMatrix / NiceArrayC }
+  {
+    code-for-last-col .tl_set:N = \l__nm_code_for_last_col_tl ,
+    code-for-last-col .value_required:n = true ,
+    unknown .code:n  = \__nm_error:n { Unknown~option~for~NiceArrayC }
+  }
+\__nm_msg_new:nnn { Unknown~option~for~NiceArrayC }
+  {
+    The~option~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~environment~
+    \{\@currenvir\}. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~options,~type~H~<return>.
+  }
+  {
+    The~available~options~are~(in~alphabetic~order):~
+    code-after,~
+    code-for-last-col,~
+    columns-width,~
+    create-extra-nodes,~
+    extra-left-margin,~
+    extra-right-margin,~
+    left-margin,~
+    name,~
+    nullify-dots,~
+    parallelize-diags~
+    renew-dots~
+    and~right-margin.
+  }
+\cs_new_protected:Nn \__nm_NiceArrayC:n
+  {
+    \bool_set_true:N \l__nm_exterior_column_bool
+    \begin { NiceArray }
+      { #1
+        >
+          {
+            \int_gincr:N \g__nm_column_int
+            \int_gset:Nn \g__nm_column_total_int
+              { \int_max:nn \g__nm_column_total_int \g__nm_column_int }
+            \hbox_set:Nw \l_tmpa_box $ % $
+              \l__nm_code_for_last_col_tl
+          }
+        l
+        < { $ % $
+            \hbox_set_end:
+            \dim_gset:Nn \g__nm_width_last_col_dim
+               {
+                 \dim_max:nn
+                   \g__nm_width_last_col_dim
+                   { \box_wd:N \l_tmpa_box }
+               }
+            \skip_horizontal:n { - 2 \arraycolsep }
+            \hbox_overlap_right:n
+              {
+                \skip_horizontal:n
+                  {
+                    2 \arraycolsep +
+                    \l__nm_right_margin_dim +
+                    \l__nm_extra_right_margin_dim
+                  }
+                \tikz
+                  [
+                    remember~picture ,
+                    inner~sep = \c_zero_dim ,
+                    minimum~width = \c_zero_dim ,
+                    baseline
+                  ]
+                \node
+                  [
+                    anchor = base ,
+                    name =
+                      nm -
+                      \int_use:N \g__nm_env_int -
+                      \int_use:N \g__nm_row_int -
+                      \int_use:N \g__nm_column_int ,
+                    alias =
+                      \str_if_empty:NF \l__nm_name_str
+                        {
+                          \l__nm_name_str -
+                          \int_use:N \g__nm_row_int -
+                          \int_use:N \g__nm_column_int
+                        }
+                  ]
+                  { \box_use:N \l_tmpa_box } ;
+              }
+          }
+      }
+  }
+\NewDocumentEnvironment { NiceArrayCwithDelims } { m m O { } m ! O { } }
+  {
+    \dim_gzero_new:N \g__nm_width_last_col_dim
+    \keys_set:nn { NiceMatrix / NiceArrayC } { #3 , #5 }
+    \bool_set_false:N \l__nm_exterior_arraycolsep_bool
+    \str_set:Nn \l__nm_pos_env_str c
+    \left #1
+    \__nm_NiceArrayC:n { #4 }
+  }
+  {
+    \end { NiceArray }
+    \right #2
+    \skip_horizontal:n \g__nm_width_last_col_dim
+  }
+\NewDocumentEnvironment { pNiceArrayC } { }
+  { \NiceArrayCwithDelims ( ) }
+  { \endNiceArrayCwithDelims }
+\NewDocumentEnvironment { vNiceArrayC } { }
+  { \NiceArrayCwithDelims | | }
+  { \endNiceArrayCwithDelims }
+\NewDocumentEnvironment { VNiceArrayC } { }
+  { \NiceArrayCwithDelims \|  \| }
+  { \endNiceArrayCwithDelims }
+\NewDocumentEnvironment { bNiceArrayC } { }
+  { \NiceArrayCwithDelims [ ] }
+  { \endNiceArrayCwithDelims }
+\NewDocumentEnvironment { BNiceArrayC } { }
+  { \NiceArrayCwithDelims \{  \} }
+  { \endNiceArrayCwithDelims }
+\keys_define:nn { NiceMatrix / NiceArrayRC }
+  {
+    code-for-first-row .tl_set:N = \l__nm_code_for_first_row_tl ,
+    code-for-first-row .value_required:n = true ,
+    code-for-last-col .tl_set:N = \l__nm_code_for_last_col_tl ,
+    code-for-last-col .value_required:n = true ,
+    unknown .code:n = \__nm_error:n { Unknown~option~for~NiceArrayRC }
+  }
+\__nm_msg_new:nnn { Unknown~option~for~NiceArrayRC }
+  {
+    The~option~'\tl_use:N\l_keys_key_tl'~is~unknown~for~the~environment~
+     \{ \@currenvir \}. \\
+    If~you~go~on,~it~will~be~ignored. \\
+    For~a~list~of~the~available~options,~type~H~<return>.
+  }
+  {
+    The~available~options~are~(in~alphabetic~order):~
+    code-after,~
+    code-for-last-col,~
+    code-for-first-row,~
+    columns-width,~
+    create-extra-nodes,~
+    extra-left-margin,~
+    extra-right-margin,~
+    left-margin,~
+    name,~
+    nullify-dots,~
+    parallelize-diags,~
+    renew-dots~
+    and~right-margin.
+  }
+\NewDocumentEnvironment { NiceArrayRCwithDelims } { m m O { } m ! O { } }
+  {
+    \int_zero:N \l__nm_nb_first_row_int
+    \dim_gzero_new:N \g__nm_width_last_col_dim
+    \keys_set:nn { NiceMatrix / NiceArrayRC } { #3 , #5 }
+    \bool_set_false:N \l__nm_exterior_arraycolsep_bool
+    \str_set:Nn \l__nm_pos_env_str c
+    \box_clear_new:N \l__nm_the_array_box
+    \hbox_set:Nw \l__nm_the_array_box
+    $ % $
+    \__nm_NiceArrayC:n { #4 }
+  }
+  {
+    \end { NiceArray }
+    $ % $
+    \hbox_set_end:
+    \dim_set:Nn \l_tmpa_dim
+      {
+        (
+          \dim_max:nn
+             { 12 pt }
+             { \g__nm_max_ht_row_one_dim + \g__nm_max_dp_row_zero_dim }
+        )
+        + \g__nm_max_ht_row_zero_dim - \g__nm_max_ht_row_one_dim
+      }
+    \hbox_set:Nn \l_tmpa_box
+      {
+        $ % $
+        \left #1
+        \vcenter
+          {
+            \skip_vertical:n { - \l_tmpa_dim }
+            \box_use_drop:N \l__nm_the_array_box
+          }
+        \right #2
+        $ % $
+        \skip_horizontal:n \g__nm_width_last_col_dim
+      }
+    \box_set_ht:Nn \l_tmpa_box { \box_ht:N \l_tmpa_box + \l_tmpa_dim }
+    \box_use_drop:N \l_tmpa_box
+    }
+\NewDocumentEnvironment { pNiceArrayRC } { }
+  { \NiceArrayRCwithDelims ( ) }
+  { \endNiceArrayRCwithDelims }
+\NewDocumentEnvironment { bNiceArrayRC } { }
+  { \NiceArrayRCwithDelims [ ] }
+  { \endNiceArrayRCwithDelims }
+\NewDocumentEnvironment { vNiceArrayRC } { }
+  { \NiceArrayRCwithDelims | | }
+  { \endNiceArrayRCwithDelims }
+\NewDocumentEnvironment { VNiceArrayRC } { }
+  { \NiceArrayRCwithDelims \| \| }
+  { \endNiceArrayRCwithDelims }
+\NewDocumentEnvironment { BNiceArrayRC } { }
+  { \NiceArrayRCwithDelims \{ \} }
+  { \endNiceArrayRCwithDelims }
+\cs_generate_variant:Nn \dim_min:nn { v n }
+\cs_generate_variant:Nn \dim_max:nn { v n }
+\cs_new_protected:Nn \__nm_create_extra_nodes:
+  {
+    \begin { tikzpicture } [ remember~picture , overlay ]
+      \int_step_variable:nnnNn \l__nm_nb_first_row_int 1 \g__nm_row_int \__nm_i
+        {
+          \dim_zero_new:c { l__nm_row_\__nm_i _min_dim }
+          \dim_set_eq:cN { l__nm_row_\__nm_i _min_dim } \c_max_dim
+          \dim_zero_new:c { l__nm_row_\__nm_i _max_dim }
+          \dim_set:cn { l__nm_row_\__nm_i _max_dim } { - \c_max_dim }
+        }
+      \int_step_variable:nnnNn 1 1 \g__nm_column_total_int \__nm_j
+        {
+          \dim_zero_new:c { l__nm_column_\__nm_j _min_dim }
+          \dim_set_eq:cN { l__nm_column_\__nm_j _min_dim } \c_max_dim
+          \dim_zero_new:c { l__nm_column_\__nm_j _max_dim }
+          \dim_set:cn { l__nm_column_\__nm_j _max_dim } { - \c_max_dim }
+        }
+      \int_step_variable:nnNn \l__nm_nb_first_row_int \g__nm_row_int \__nm_i
+        {
+          \int_step_variable:nNn \g__nm_column_total_int \__nm_j
+            { \cs_if_exist:cT
+                { pgf@sh@ns@nm - \int_use:N \g__nm_env_int - \__nm_i- \__nm_j }
+                {
+                  \tikz@parse@node \pgfutil@firstofone
+                    ( nm - \int_use:N \g__nm_env_int
+                         - \__nm_i - \__nm_j .south~west )
+                  \dim_set:cn { l__nm_row_\__nm_i _min_dim}
+                    { \dim_min:vn { l__nm_row _ \__nm_i _min_dim } \pgf@y }
+                  \seq_if_in:NxF \g__nm_multicolumn_cells_seq { \__nm_i - \__nm_j }
+                    {
+                      \dim_set:cn { l__nm_column _ \__nm_j _ min_dim}
+                        { \dim_min:vn { l__nm_column _ \__nm_j _min_dim } \pgf@x }
+                    }
+                 \tikz@parse@node \pgfutil@firstofone
+                   ( nm - \int_use:N \g__nm_env_int - \__nm_i - \__nm_j .north~east )
+                  \dim_set:cn { l__nm_row _ \__nm_i _ max_dim }
+                    { \dim_max:vn { l__nm_row _ \__nm_i _ max_dim } \pgf@y }
+                  \seq_if_in:NxF \g__nm_multicolumn_cells_seq { \__nm_i - \__nm_j }
+                    {
+                      \dim_set:cn { l__nm_column _ \__nm_j _ max_dim }
+                        { \dim_max:vn { l__nm_column _ \__nm_j _max_dim } \pgf@x }
+                    }
+                }
+            }
         }
+      \tikzset { name~suffix = -medium }
+      \__nm_create_nodes:
+      \int_set:Nn \l__nm_nb_first_row_int 1
+      \int_step_variable:nnnNn 1 1 { \g__nm_row_int - 1 } \__nm_i
+        {
+          \dim_set:cn { l__nm_row _ \__nm_i _ min _ dim }
+            {
+              (
+                \dim_use:c { l__nm_row _ \__nm_i _ min _ dim } +
+                \dim_use:c { l__nm_row _ \int_eval:n { \__nm_i + 1 } _ max _ dim }
+              )
+              / 2
+            }
+          \dim_set_eq:cc { l__nm_row _ \int_eval:n { \__nm_i + 1 } _ max _ dim }
+            { l__nm_row_\__nm_i _min_dim }
+        }
+      \int_step_variable:nnnNn 1 1 { \g__nm_column_int - 1 } \__nm_j
+        {
+          \dim_set:cn { l__nm_column _ \__nm_j _ max _ dim }
+            {
+              (
+                \dim_use:c
+                  { l__nm_column _ \__nm_j _ max _ dim } +
+                \dim_use:c
+                  { l__nm_column _ \int_eval:n { \__nm_j + 1 } _ min _ dim }
+              )
+              / 2
+            }
+          \dim_set_eq:cc { l__nm_column _ \int_eval:n { \__nm_j + 1 } _ min _ dim }
+            { l__nm_column _ \__nm_j _ max _ dim }
+        }
+      \dim_sub:cn
+        { l__nm_column _ 1 _ min _ dim }
+        \g__nm_left_margin_dim
+      \dim_add:cn
+        { l__nm_column _ \int_use:N \g__nm_column_int _ max _ dim }
+        \g__nm_right_margin_dim
+      \tikzset { name~suffix = -large }
+      \__nm_create_nodes:
+      \end{tikzpicture}
+      \cs_set:Nn \__nm_create_extra_nodes: { }
+  }
+\cs_new_protected:Nn \__nm_create_nodes:
+  {
+    \int_step_variable:nnnNn \l__nm_nb_first_row_int 1 \g__nm_row_int \__nm_i
+      {
+        \int_step_variable:nnnNn 1 1 \g__nm_column_total_int \__nm_j
+          {
+            \coordinate ( __nm~south~west )
+               at ( \dim_use:c { l__nm_column_ \__nm_j _min_dim } ,
+                    \dim_use:c { l__nm_row_ \__nm_i _min_dim } ) ;
+            \coordinate ( __nm~north~east )
+               at ( \dim_use:c { l__nm_column_ \__nm_j _max_dim },
+                    \dim_use:c { l__nm_row_ \__nm_i _max_dim } ) ;
+            \node
+              [
+                node~contents = { } ,
+                fit = ( __nm~south~west ) ( __nm~north~east )  ,
+                inner~sep = \c_zero_dim ,
+                name = nm - \int_use:N \g__nm_env_int - \__nm_i - \__nm_j ,
+                alias =
+                  \str_if_empty:NF \g__nm_name_str
+                    { \g__nm_name_str - \__nm_i - \__nm_j }
+              ]
+              ;
+          }
+      }
+    \__nm_seq_mapthread_function:NNN
+      \g__nm_multicolumn_cells_seq
+      \g__nm_multicolumn_sizes_seq
+      \__nm_node_for_multicolumn:nn
+  }
+\cs_new_protected:Npn \__nm_extract_coords: #1 - #2 \q_stop
+  {
+    \cs_set:Npn \__nm_i { #1 }
+    \cs_set:Npn \__nm_j { #2 }
+  }
+\cs_new_protected:Nn \__nm_node_for_multicolumn:nn
+  {
+    \__nm_extract_coords: #1 \q_stop
+    \coordinate ( __nm~south~west ) at
+      (
+        \dim_use:c { l__nm_column _ \__nm_j _ min _ dim } ,
+        \dim_use:c { l__nm_row _ \__nm_i _ min _ dim }
+      ) ;
+    \coordinate ( __nm~north~east ) at
+      (
+        \dim_use:c { l__nm_column _ \int_eval:n { \__nm_j + #2 - 1 } _ max _ dim} ,
+        \dim_use:c { l__nm_row _ \__nm_i _ max _ dim }
+      ) ;
+    \node
+      [
+        node~contents = { } ,
+        fit = ( __nm~south~west ) ( __nm~north~east ) ,
+        inner~sep = \c_zero_dim ,
+        name = nm - \int_use:N \g__nm_env_int - \__nm_i - \__nm_j ,
+        alias =
+          \str_if_empty:NF \g__nm_name_str { \g__nm_name_str - \__nm_i - \__nm_j }
+      ]
+      ;
+  }
 \ProcessKeysOptions {NiceMatrix}
-\cs_new:Npn \__nicem_seq_mapthread_function:NNN #1#2#3
-  {\group_begin:
-   \int_step_inline:nnnn 1 1 {\seq_count:N #1}
-         {\seq_pop:NN #1 \l_tmpa_tl
-          \seq_pop:NN #2 \l_tmpb_tl
-          \exp_args:NVV #3 \l_tmpa_tl \l_tmpb_tl}
+\cs_new:Npn \__nm_seq_mapthread_function:NNN #1 #2 #3
+  {
+   \group_begin:
+   \int_step_inline:nnnn 1 1 { \seq_count:N #1 }
+     {
+       \seq_pop:NN #1 \l_tmpa_tl
+       \seq_pop:NN #2 \l_tmpb_tl
+       \exp_args:NVV #3 \l_tmpa_tl \l_tmpb_tl
+     }
    \group_end:
   }
-\cs_set:Nn \__nicem_renew_matrix:
-    {\RenewDocumentEnvironment {pmatrix} {}
-         {\begin{pNiceMatrix}}
-         {\end{pNiceMatrix}}
-     \RenewDocumentEnvironment {vmatrix} {}
-         {\begin{vNiceMatrix}}
-         {\end{vNiceMatrix}}
-     \RenewDocumentEnvironment {Vmatrix} {}
-         {\begin{VNiceMatrix}}
-         {\end{VNiceMatrix}}
-     \RenewDocumentEnvironment {bmatrix} {}
-         {\begin{bNiceMatrix}}
-         {\end{bNiceMatrix}}
-     \RenewDocumentEnvironment {Bmatrix} {}
-         {\begin{BNiceMatrix}}
-         {\end{BNiceMatrix}}}
+\cs_set_protected:Npn \__nm_renew_matrix:
+  {
+    \RenewDocumentEnvironment { pmatrix } { }
+      { \pNiceMatrix }
+      { \endpNiceMatrix }
+    \RenewDocumentEnvironment { vmatrix } { }
+      { \vNiceMatrix }
+      { \endvNiceMatrix }
+    \RenewDocumentEnvironment { Vmatrix } { }
+      { \VNiceMatrix }
+      { \endVNiceMatrix }
+    \RenewDocumentEnvironment { bmatrix } { }
+      { \bNiceMatrix }
+      { \endbNiceMatrix }
+    \RenewDocumentEnvironment { Bmatrix } { }
+      { \BNiceMatrix }
+      { \endBNiceMatrix }
+  }
 \endinput
 %%
 %% End of file `nicematrix.sty'.