maybe the question is a bit too high level, but I'll try anyway.
Is there something to get an automatic "merge down" behavior as shown by the MWE? Leftmost columns have higher priority, so they prevent the merge of columns on their right.
Code: Select all
\documentclass{article}
\usepackage{supertabular}
\begin{document}
\begin{supertabular}{|l|l|l|}\hline
a & a1 & a11 \\ \hline
a & a1 & a12 \\ \hline
a & x & a12 \\ \hline
a & x & a13 \\ \hline
b & x & b11 \\ \hline
\end{supertabular}
%
$\Rightarrow$
%
\begin{supertabular}{|l|l|l|} \hline
a & a1 & a11 \\ \cline{3-3}
& & a12 \\ \cline{2-3}
& x & a12 \\ \cline{3-3}
& & a13 \\ \hline
b & x & b11 \\ \hline
\end{supertabular}
\end{document}
