%%
%% The LaTeX Companion, 3ed
%%
%% Example 11-3-9 on page II-159 in "bigdelim --- Delimiters around and inside arrays".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3examargin}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{159.0pt}

%StartShownPreambleCommands
\usepackage{bigdelim}
%StopShownPreambleCommands

\begin{document}
\begin{equation}
 \begin{array}{r@{\,}ccc@{\,}l}
   & 1 & 2 & 3 & \hspace{2mm}\rdelim]{3}{*}[quite] \\
   & 0 & 1 & 2                                     \\
   & 0 & 0 & 1 & \rdelim]{3}{*}[special]           \\
   & 0 & 0 & 0                                     \\
  \ldelim\{{-5}{*}[This is] & & \Delta    \end{array}
\end{equation}
\end{document}