iul \- indicate underlining
This filter provides the same function as the
breaking underlining onto separate lines as dashing with `\-'.
It is handy when you want to look at the underlining which is present
output stream on a soft-copy terminal.
nroff \-ms pcxin1.n | iul
has all of the features of
is superfluous is some sense.
is, however, much more efficient that