%%
%% The LaTeX Companion, 3ed
%%
%% Example 4-3-23 on page I-349 in "paracol --- Several text streams aligned".
%%
%% 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{tlc3exa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{183.0pt}

  \setlength\parindent{0pt}
  \addtolength\textwidth{-10pt}

  \setlength\columnsep{35pt}  % no longer really necessary but we keep it
                              % so that the examples in the book are comparable

%StartShownPreambleCommands
 \usepackage{lineno,paracol}
 \definecolumnpreamble{0}{\linenumbers}
 \definecolumnpreamble{1}{\nolinenumbers}
%StopShownPreambleCommands

\begin{document}
\begin{paracol}{3}
   Left     \\ \mbox{}  \switchcolumn
   Middle and more      \switchcolumn
   Right on two lines   \switchcolumn*
   Left again and again \switchcolumn  Middle
 \end{paracol}
\end{document}