Hi onf,

At 2025-01-04T01:23:02+0100, onf wrote:
> > > Note that \f[CBI] will break in old troffs due to the "new" \f[]
> > > syntax, so a warning should probably be emitted. And I have no
> > > idea how good support for {bold,italic} Courier is in older troffs
> > > either.
> >
> > Poor, in general.  Where Courier bold-italic existed, it was
> > sometimes called "CX".
> 
> I meant support for CB and CI, not CBI.

Also poor, outside of the horizon I previously articulated.  :(

System V Unix supported these names _only_ on the "aps" device
(Autologic APS-5).  Plan 9 doesn't.  DWB 3.3 doesn't.

The "aps" device on Solaris 10 troff supports CB but not CI.

> Speaking of the left italic correction (\,), could you please give me
> some example(s) where it's actually useful? I have yet to see a single
> instance where it changes anything... (I don't rule out the
> possibility that I may be using it incorrectly or that my fonts might
> be misconfigured, though.)

Sure.  I'm attaching an extract of groff_diff(7) in PDF, which not only
explains the issue but illustrates the problem it solves.

Our Texinfo manual has the same textual content but doesn't deliberately
exhibit the problem.

> > [5] I admit I'm a little fuzzy on Plan 9 from User Space's
> >     objectives for its troff.  I can say that the pace of its
> >     development is not swift.  I don't think Plan 9 advocates pick
> >     up the system to use its typesetter.
> 
> My understanding is that Plan 9 from User Space is merely providing a
> port of the Plan 9 program.

It's a whole OS!  Give it credit... ;-)

> My impression of Plan 9's troff is that it's a poorly maintained
> descendant of DWB troff that's used only to format manpages.

I wouldn't say _poorly_ maintained; its commit rate seems to match or
even exceed its defect rate.  This could illustrate (1) low adoption or
(2) adequacy for the (limited?) purposes to which people apply it.

I'd like to see an attempt at reconstructing DWB 3.4 from the existing
DWB 3.3 code base (made portable) and an old snapshot of Plan 9, maybe
circa 2000.  It'd be good to have a plausible exhibit of the end of the
line for AT&T Unix troff--what the body looked like at the murder scene.

https://lists.gnu.org/archive/html/groff/2022-12/msg00097.html

Regards,
Branden