%%
%% The LaTeX Companion, 2ed (second printing August 2004)
%%
%% Example 2-2-1 on page 25.
%%
%% Copyright (C) 2004 Frank Mittelbach, Michel Goossens,
%%    Johannes Braams, David Carlisle, and Chris Rowley
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See http://www.latex-project.org/lppl.txt for details.
%%

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{207.0pt}
\StartShownPreambleCommands
\renewcommand\thesection{\Alph{section}}

\StopShownPreambleCommands
\begin{document}
\section{Different-looking section}
\subsection{Different-looking subsection}
Due to the default definitions not only the
numbers on sections change, but lower-level
sectioning commands also show this
representation of the section number.
\end{document}