[Groff] underlining

[Bernd Warken]

1) I propose to add documentation for underlining in `groff.7'.

2) A long time ago, Werner Lemberg wrote an ul.tmac and publisheed it only in 
this
mailing list.  But I could not find this tmac file somewhere else.

3) There is a `groff' request `.ul', that just generates an italic font change.
In nroff (ttyt/latin1 mode), italic is always printed as underlined - so .ul 
works
there.  But in `troff', italic mode is kept.  So a better programming for `.ul'
in `troff' would be useful.

4) The following macro can basically handle underlining also in `troff', maybe 
it should
be improved a bit.  I forgot, where I got this macro definition,  I use it since
several years in some of my man-pages.

5) Macro:
.\" .UNDERLINE before underlined after
.de UNDERLINE
.  ie n \\$1\fI\\$2\fP\\$3
.  el \\$1\Z'\\$2'\v'.25m'\D'l \w'\\$2'u 0'\v'-.25m'\\$3
..

6) Unfortunately, `doclifter' has much trouble with definitions of all kind.  
For that
the following parts without `.de' can be used.

.\" Copy the following lines for any underlined part
.
.\" before, not underlined, choose \& when empty
.ds u1 before
.\" this is underlined
.ds u2 in
.\" after, not underlined, choose \& when empty
.ds u3 after
.
.ie n \(*u1\fI\*(u2\fP\*(u3\"
.el \(*u1\Z'\*(u2'\v'.25m'\D'l \w'\*(u2'u 0'\v'-.25m'\*(u3\"
..

7) I propose to include similar documentations about underlining in groff.7
(man/groff.man).

Bernd Warken