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%%  Example 01-08-3 
%%  Copyright (C) 2017 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
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\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{328.62788pt}

%StartShownPreambleCommands
\usepackage{amsmath}
%StopShownPreambleCommands
\begin{document}
\begin{align*}
\Biggl[-2x - 4y\Biggr]& \quad\text{\emph{with} ``l'': }
     \begin{array}{l}
       \text{\textbullet\ tight spacing after opening fence;}\\
       \text{\textbullet\ first ``$-$'' symbol treated as unary operator}
     \end{array}\\
\Bigg[ -2x - 4y\Bigg]&  \quad\text{without ``l'': }
     \begin{array}{l}
       \text{\textbullet\ loose spacing after opening fence;}\\
       \text{\textbullet\ first ``$-$'' symbol treated as binary operator}
     \end{array}\\
\biggl(+3u + 7v\biggr)&\\
\bigg( +3u + 7v\bigg) &\\
\Bigl\vert \div 2x \times 4y\Bigr\vert &\\
\Big\vert  \div 2x \times 4y\Big\vert  &\\
\bigl\{ \times 3u \div 7v\bigr\} &\\
\big\{  \times 3u \div 7v\big\}  &
\end{align*}
\end{document}
