%% 
%%  Example 02-11-6 
%%  Copyright (C) 2016 Herbert Voss
%% 
%% ==== 
% Show page(s) 1
%% 
%% 
\documentclass[]{screxa}
\pagestyle{empty}
\setlength\textwidth{134.31393pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{amsmath}
%StopShownPreambleCommands
\begin{document}
\[
  \sideset{_{\text{LowerLeft}}%
           ^{\text{UpperLeft}}}%
          {_{\text{LowerRight}}%
           ^{\text{UpperRight}}}\sum_{B}^{T}
\]
\end{document}
