%%
%% The LaTeX Companion, 3ed
%%
%% Example 4-1-35 on page I-282 in "amsthm --- Providing headed lists".
%%
%% 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{135.0pt}


  \usepackage{microtype}  % improve the line breaking in short measure


%StartShownPreambleCommands
\usepackage{amsthm}
\newtheorem{lem}{Lemma} \newtheorem*{ML}{Mittelbach's Lemma}
%StopShownPreambleCommands

\begin{document}
\begin{lem}[Main] The \LaTeX{} Companion
  complements any \LaTeX{} introduction.
\end{lem}
\begin{ML} The \LaTeX{} Companion contains
  packages for all important application areas.
\end{ML}
\end{document}