This is accurate. I was briefly involved with sqtroff, because it was brought to York U
by one of the founders (david slocombe) to publish York's newsletter. 
see this for coach house press history. possibly the first (outside bell) unix-based publisher.
https://publishing.sfu.ca/2015/12/coach-house-press-early-digital-period/

... oz

On Mon, Mar 7, 2022, at 11:55 AM, Kevin Bowling wrote:
> Interesting. That sounds like a different commercial strain, "SoftQuad
> was started in order to improve automated typesetting at Toronto's
> Coach House Press, and for many years developed an enhanced commercial
> version of the text formatting program troff, developed under license
> from AT&T, called sqtroff. It was sold with a suite of associated
> programs, corresponding to AT&T's Documenter's Workbench, under the
> name SoftQuad Publishing Software (SQPS)."
> 
> On Mon, Mar 7, 2022 at 6:28 AM Jaap Akkerhuis <jaapna@xs4all.nl> wrote:
> >
> >
> >
> > > I see documentation of 1.0 (i.e
> > > https://archive.org/details/sysv-dwb/page/n5/mode/2up)
> > > I see a copy of 2.0 for 3B2 (i.e.
> > > https://archives.loomcom.com/3b2/software/Documenters_Workbench/)
> > >
> > > From there things get a little less clear, it seems like we jump to
> > > 3.2 with SysVR3.2?
> >
> > The jump might be due to the effect that for quite a while outside
> > AT&T it was marketed by SoftQuad (Toronto).  (See also
> > <https://en.wikipedia.org/wiki/SoftQuad_Software>).
> >
> >         jaap
> >
> 

ozan s. yigit
http://nextbit.blogspot.com
*to live fully is to wage constant battle against the mundane.* -- guy tal