At 2023-05-13T12:52:06-0500, Dave Kemper wrote: > On 5/13/23, G. Branden Robinson <g.branden.robin...@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.
On DWB 3.3 troff, a direct descendant of Kernighan troff, and the basis for Heirloom Doctools troff, the second and third lines match: x T post x res 720 1 1 x init V0 p1 x font 1 R # unnecessary font loading snipped s10 f1 H720 V120 cf 33o50owh125cb 50a44rn120 0 H720 V240 cf 33o50owh150cb 50a44rn120 0 H720 V360 cf 33o50oh150cb 50a44rn120 0 x trailer V7920 x stop > Both of these are consistent with their respective documentation. 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. As can be seen in my numerous arguments with Ralph Corderoy, I find the Galilean episteme superior to the pontifical one. Secondly, Heirloom's arithmetic seems to be slightly off. x T ps x res 72000 1 1 x init V0 p1 x font 1 R /home/branden/heirloom/lib/doctools/font/devps/R.afm 4 # unnecessary font loading snipped s10 f1 x X LC_CTYPE en_US.UTF-8 H72000 V12000 cf h3330co h5000co wh14990cb h5000ca h4440cr n12000 0 H72000 V24000 cf h3330co h5000co wh18320cb h5000ca h4440cr n12000 0 H72000 V36000 cf h3330co h5000co h15000cb h5000ca h4440cr n12000 0 x trailer V792000 x stop In case the difference is hard to make out: h3330co h3330co h5000co h5000co wh14990cb h15000cb h5000ca h5000ca h4440cr h4440cr ...but I'll grant that 1/7,200 inch difference is unlikely to be noticed, even if it accumulated several times across an output line. Maybe if one's printer does better than 600dpi... I won't hold my breath waiting for anyone to point at Heirloom and shriek "deviation!" like Donald Sutherland at the end of the 1978 _Invasion of the Body Snatchers_. Partisans know one thing, and that's to stay partisan. Regards, Branden
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