Re: .ss paragraph-style-footnote example, then and now

[Dave Kemper]

On 4/4/21, G. Branden Robinson <g.branden.robinson@gmail.com> wrote:
> Yes, I agree that those are both desirable points to illustrate.

OK.  I filed http://savannah.gnu.org/bugs/index.php?60404 as a reminder.

> The first is more economical, but the second is much more illustrative
> of end of sentence detection and what, precisely, \c does.  Maybe it
> will suffice to have the latter only in the mailing list archives.

Yeah, after ruminating another week, I still have no clear winner in
my mind between these two or the original (.nop) formulation.  I have
a very slight preference for the .nop version because, as you note,
it's tough to *explain* what .nop is good for, so the more practical
illustrations of its use in the manual, the better.  But you've
offered good reasons for using your versions as well.

> I have a bias against .nop at present because I don't know how to
> explain it convincingly to people.  "It's syntactic sugar for '.if 1'!"
> feels feeble to me.

I think that's perfectly fine as an explanation of what it *does*.
But it sidesteps the obvious follow-up question, "Why you you ever
need to say '.if 1'?"

(An actual ".if 1" does have some utility, if you're in the
development phase and want to try something different ways; changing
".if 1" to ".if 0" and vice versa is easier in some editors than
repeatedly commenting and uncommenting a line.  But using ".nop" in
place of ".if 1" removes that benefit.)

> As comprehensive at it is, there is much that is undocumented in CSTR
> #54.  The following were all true of Unix V7 troff.
>
> (1) .ss was honored only for typesetter output, i.e. "troff mode";

This is documented by the "T" in the "Notes" column.  But yes, good
observations on the other omissions.

> Given the above, I conjecture that V7 .ss was used only in extremis, to
> fix bad justification (to both margins) on a per-output-line basis.  It
> wasn't _useful_ for tweaking inter-sentence spacing, but applied to
> every inter-word space on a line and therefore there would be no
> _reason_ to change it within an output line.

This makes sense, and I suppose could even be seen as a drawback to
groff's implementation, in that this technique is harder to control if
the .ss takes effect immediately rather than at the next typeset line
break.