[Groff] "Bib" preprocessor?

[John Gardner]

A program called *bib* appears to exist (or have once existed) that was
supposedly similar or identical to *refer*. However, aside from a few
fleeting references to its existence on Wikipedia
<https://en.wikipedia.org/wiki/Troff#Preprocessors> and Troff.org
<http://www.troff.org/prog.html>, I'm finding very little info on the
program.

Does anybody know how it differed from the more familiar *refer* program
that's bundled with the GNU suite?

Googling has tossed up a few similar-sounding names like *roffbib* and
*addbib*, but it's unclear if they're at all related..