\begin{Schunk}
\begin{Sinput}
 options(contrasts=c("contr.sum", "contr.poly"))
 contrasts(Chile$region)
\end{Sinput}
\begin{Soutput}
   [,1] [,2] [,3] [,4]
C     1    0    0    0
M     0    1    0    0
N     0    0    1    0
S     0    0    0    1
SA   -1   -1   -1   -1
\end{Soutput}
\end{Schunk}
