[Groff] trouble with \_

[walter harms]

hi list,

I run into a problem that left me confused.
I wanted to use \_ to draw a line in a table.
My test programm looks like that:

.TS
tab(|);
l l l.
Geraet                | Seriennummer               | Bemerkung
_
xxxxxxxxxxxxxx   |11111111111111111  |\_
xxxxxxxxxxxxxx   |11111111111111111  |\_
xxxxxxxxxxxxxx   |11111111111111111  |\_
xxxxxxxxxxxxxx   |11111111111111111  |\_
xxxxxxxxxxxxxx   |11111111111111111  |\_
.TE

when i run my test it looks like that:

groff -t -Tascii line.tbl
grotty:line.tbl:7: character above first line discarded
Geraet                    Seriennummer                   Bemerkung
-------------------------------------------------------------------
xxxxxxxxxxxxxx           11111111111111111              _
xxxxxxxxxxxxxx           11111111111111111              _
xxxxxxxxxxxxxx           11111111111111111              _
xxxxxxxxxxxxxx           11111111111111111              _
xxxxxxxxxxxxxx           11111111111111111              _


I expected that \_ will be expanded to ____________________

(also no idea why grotty complains).
btw: the example in UTP p. 180 works fine to it is not a broken macro or so.


re,
 wh