%% 
%%  Example 07-05-2 
%%  Copyright (C) 2017 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{158.31393pt}
\setlength\parindent{0pt}
\usepackage[T1]{fontenc}
%StartShownPreambleCommands
\usepackage{amsmath,calc}
%StopShownPreambleCommands
\begin{document}
\begin{align*}
  \qquad\overbrace{\qquad\qquad}^o\qquad\\[-16pt]
  \underbrace{\qquad\qquad}_{u1}
  \underbrace{\qquad\qquad}_{u2}
\end{align*}
\end{document}
