[Groff] tbl using \$_

[walter harms]

Hi list,
After printing my document i found that \_ does not do what i expected.
the line is to high more like - than _.
After reading the UTP book again i got the inpression that \$_ will do
what i want but that resulted in   "bad argument name `_'"

Then i tried \R_ what is very near what i would like to have. (i also tried 
\R\(ru).

I have a simple table here that describes what i want. I need some empty lines
to people can write some remarks in that line. Is there a simple way to do that 
?

re,
 wh

.TS
tab(|);
l l l.
Device           | Serial            | Remark
_
xxxxxxxxxxxxxx   |11111111111111111  |\_
xxxxxxxxxxxxxx   |11111111111111111  |\_
xxxxxxxxxxxxxx   |11111111111111111  |\_
xxxxxxxxxxxxxx   |11111111111111111  |\_
xxxxxxxxxxxxxx   |11111111111111111  |\_
.TE