Hi Jon,
Steffen Nurpmeso writes:
Note that heirloom doctools (on github) is a
SysV-derived *roff
Wow, thanks for mentioning this. I was unaware of it. When
I recently wrote that it would be nice to add TeX's 2D formatting
to troff I didn't realize that it had already been done.
Something new to play with.
There's also Neatroff by Ali Gholami Rudi. It has TeX's paragraph
formatting and several other new features, taking from Plan 9,
Heirloom, and Groff. IIRC, it's an implementation from scratch.
https://litcave.rudi.ir links to its introductary PDF in the first
paragraph,
https://litcave.rudi.ir/neatroff.pdf, and a Typesetting
section below the change-log.
--
Cheers, Ralph.