H
g/^/s/@BEGCH@/\\tdLM /
g/^/s/@ENDCH@/\\tdRM/
/\\startexdiff/ a
\newcommand{\tdLM}{\mbox{\bf [\hspace{-0.6ex}[\hspace{-0.7ex}[\hspace{-0.6ex}[\hspace{-0.2ex}}}    
\newcommand{\tdRM}{\mbox{\bf\hspace{-0.2ex}]\hspace{-0.6ex}]\hspace{-0.7ex}]\hspace{-0.6ex}]}}
.
1,$p
q

Written by Hugo Krawczyk, May 1993.