[TUHS] [TUHS/groff] Provenance of .SB macro in man pages

[reed at reedmedia.net]

On Sun, 26 Jan 2020, G. Branden Robinson wrote:

> I'm inlining my findings in rendered and source form below, but there's
> one feature I haven't been able to sort out--where did .SB (small bold)
> come from?  The oldest groff release I can find online is 1.02 (June
> 1991), and .SB is already there, but I can't find it anywhere else.  Is
> it a GNUism?  Did it perhaps appear in a proprietary Unix first?

I see .SB used in the 
C Manual - Language
Edited by R.P.A. Collinson
Document No: DOC/UNIX.K3.10/1
and UKC IO Library docs also from Collinson at Univ. of Kent.
as found in the usenix-78-uk1 tape.
Maybe that is uk1.tar at 
https://www.tuhs.org/Archive/Applications/Spencer_Tapes/

I also see a SB Stymie Bold font in v7 troff.