Larry McVoy <lm(a)mcvoy.com> wrote:
Tim O'Reilly got it, wrote a book about it but I
think it was
too little too late.
That book was open sourced ~ 2 decades ago. It was scanned, OCR'ed
and converted back into troff. See
https://www.oreilly.com/openbook/utp/
and in particular
https://github.com/larrykollar/Unix-Text-Processing .
Arnold