Re: units used in `ss` request (was: device-dependent warnings)

[Dave Kemper]

On 5/13/23, G. Branden Robinson <g.branden.robinson@gmail.com> wrote:
>> At 2023-05-10T12:28:02-0500, Dave Kemper wrote:
>> > And I just learned (or maybe relearned) this is a deviation from
>> > AT&T troff's .ss units, which are a fixed 1/36 em.
>
> I am beginning to think that it was only Ossanna troff for which that
> was true, and CSTR #54 was simply never updated in this respect.

True, I was going by CSTR #54 rather than observed behavior.  However,
the Heirloom documentation (derived from CSTR #54) echoes the 1/36-em
claim, and its behavior appears to be consistent with that.

.nf
.ss 36
foo bar
.ss 48
foo bar
foo\h'1m'bar

In Heirloom troff, the space on the first and third lines match.  In
groff (both 1.22.4 and 1.23 rc4), the second and third lines do.  Both
of these are consistent with their respective documentation.