ptx(1) obscurity

[utzoo!henry]

The manual page for ptx gives a fairly good description of the program,
but it is not obvious to non-troff-hackers how to get decent formatting
of the output (i.e. what ".xx" macro to supply).  After digging through
the stuff used to prepare the manual and doing a bit of experimenting,
I added the following to our ptx(1) manual page (sorry about all the
backslashes, that's troff for you):

.SH EXAMPLE
The following is a reasonably-minimal
set of
.I nroff
statements which will format
.I ptx
output reasonably;  the style is similar to the index for this manual.
The spacings may need adjustment for different output devices.
.PP
.RS
.nf
\&.de xx
\&.if !""\\\\$1" \\\\$1\\fI\\a\\fR\\\\$2\\t\\\\$3\\fI\\a\\fR\\t\\\\$5
\&.if !""\\\\$4" \\t\\\\$2\\t\\\\$3\\fI\\a\\fR\\\\$4\\t\\\\$5
\&.if ""\\\\$1\\\\$4" \\t\\\\$2\\t\\\\$3\\fI\\a\\fR\\t\\\\$5
\&..
\&.nf
\&.ta 3.7iR 3.95iL 7.65iR 7.8iR
.RE