[texhax] Oblique cancellation with plain TeX

[Rodolfo Medina]

Hi all.

In internet I couldn't find a solution for plain TeX (cancellation of
mathematical text with diagonal line over it).  I found this suggestion:

\newbox\TestBox
\def\Remove #1 {\setbox\TestBox=\hbox{$#1$}%
        \leavevmode\rlap{\vrule height 2.5pt depth-1.75pt width\wd\TestBox}%
        \box\TestBox\ }

coming from Barbara Beeton (thanks, Barbara...!) that produces an horizontal
line instead.

Please help whoever can.

Thanks,

Rodolfo