par1\par
\parindent=0pt
par2\par

\setbox0=\vbox{%
\leftskip=50pt
\rightskip=150pt
\begin{calstable}
\cals@setpadding{}
\cals@setcellprevdepth{}
\def\borderL{0pt}
\let\borderR=\borderL
\let\borderT=\borderL
\let\borderB=\borderL
\colwidths{{100pt}}
\brow \cell{} \ht\cals@current@row=20pt \erow
\end{calstable}
}
\showbox0
\box0
par3\par
par4\par