%%
%% The LaTeX Companion, 3ed
%%
%% Example 4-3-22 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{159.0pt}

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

%StartShownPreambleCommands
\usepackage{lineno,paracol} \linenumbers
\setlength\columnsep{35pt}
%StopShownPreambleCommands

\begin{document}
 \begin{paracol}{3}[Numbered locally (issue empties)]
 \synccounter{linenumber}
   Left \switchcolumn  Middle \\ Middle \switchcolumn
                       Right  \\ Right  \switchcolumn*
 \addtocounter{linenumber}{1}
   Left again and again \switchcolumn  Middle
 \end{paracol}
 \begin{paracol}{3}[Numbered locally (no sync!)]
   Left \switchcolumn Middle \switchcolumn  Right
 \end{paracol}
\end{document}