%%
%% The LaTeX Companion, 3ed
%%
%% Example 3-6-19 on page I-251 in "vertbars --- Adding bars to paragraphs".
%%
%% 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{171.0pt}
\addtolength\textwidth{-25pt} % for the bars in the example
\usepackage{microtype} % improve h&j in example
%StartShownPreambleCommands
\usepackage{vertbars} \setlength\barwidth{1pt}
%StopShownPreambleCommands
\begin{document}
This paragraph has no bar.
\begin{vertbar}
The environment always starts a new paragraph
and can only contain full paragraphs.
\begin{vertbar}
Nesting is possible as shown here but only
on paragraph boundaries.
\end{vertbar}
Breaks across columns or pages are also
possible and the bar continues.
\end{vertbar} Another paragraph without a bar.
\end{document}
