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

[G. Branden Robinson]

Hi Dave,

At 2023-05-23T15:24:26-0500, Dave Kemper wrote:
> On 5/21/23, G. Branden Robinson <g.branden.robinson@gmail.com> wrote:
> > At 2023-05-13T12:52:06-0500, Dave Kemper wrote:
> >> 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.
> >
> > On DWB 3.3 troff, a direct descendant of Kernighan troff, and the
> > basis for Heirloom Doctools troff, the second and third lines match:
> 
> The behavioral divergence between DWB 3.3 and Heirloom surprises me.
> I wondered if maybe this was the result of a different Times space
> width in Heirloom, but if I'm reading its metrics files correctly
> (which I admit is partly educated guesswork on my part), the widths
> appear to match groff's:
> 
> $ cd heirloom/local/ucblib/doctools/font/devps
> $ fgrep 'N space ' *
> B.afm:C 32 ; WX 250 ; N space ; B 0 0 0 0 ;
[snip]

As I understand it, Heirloom loads font files directly (a feature many
would like to see added to groff).  So maybe these AFMs don't match the
actual font in use?

> > I don't think I trust Heirloom here.  First, I suspect what they did
> > was treat the CSTR #54 as more authoritative than empirically
> > measured formatter behavior.
> 
> I can't rule that out, but it sure goes against (my understanding of)
> the general philosophy of the Heirloom project (which is to use only
> the original source code for original functionality, not
> reverse-engineering any of it).

My wild-ass speculation is that, upon adding a feature that demanded
refactoring of legacy troff code, and without a TRIP test to guide them,
they could have followed CSTR #54 as a specification rather than the
implementation.  Perhaps without full awareness of the divergence
between the two; I just documented a new (and unrelated) CSTR #54
erratum this week that's been lying in plain sight for decades...[1]

> I guess the upshot is that rather than a groff difference that needs
> to be documented, this is a CSTR #54 erratum (which groff could still
> document,

That is my view.

> but it feels less important).

Here I don't agree; I mean to document every CSTR #54 behavioral erratum
that we become aware of.  Bible thumpers can just die mad about it.[2]

Regards,
Branden

[1] 
https://git.savannah.gnu.org/cgit/groff.git/commit/?id=8c22fb258c2a5fd0d9b52c9d694915c081e774dd
[2] And future contributors can rip the notations back out after I've
    died mad about something else ;-).  I'll have done my part to inform
    the historical record.

signature.asc
Description: PGP signature