🚀 go-pugleaf

>I heard somewhere that RMS started out with Gosling's PD emacs.

Gnu Emacs was written from scratch.  There are major differences in
design between it and Gosling's work.  As far as I know, the only
exception is that a piece of the display code was based on Gosling's.
That code represented a very small part of the total Gnu Emacs.  There
was reason to believe that certain versions of this code were public
domain, so I think RMS had used it in good faith.  However enough
claims to the contrary were made that he decided to rewrite the
relevant code from scratch.  Even after that rewrite, there were some
remaining similarities.  However Unipress (who now have marketing
rights to Gosling's code) said they were satisified, and so the issue
dropped.  (Indeed as far as I know, Unipress hadn't been one of the
complainers in the first place.)

I should note by the way that Gosling said that his Emacs is not and
never was public domain.  There were various disputes as to the exact
status of various versions and pieces of it.  But if you refer to it
as PD, you should at least realize that you are making a rather
dubious statement.  Gnu is of course not public domain either, since
it is covered by the somewhat quixotic Gnu public license.