If by "RFC" you mean an IETF RFC document (one of Internet Engineering Task Force's Requests For Comments) -- as is what RFC reads to me, and (I would venture guessing) zino -- how does the old Nettle contain one in this case? Is it an implementation of some non-DFSG-free RFC, which a later Nettle release supercedes with a (DFSG-wise) free one?

Any Debian specific acronym (if such) can not be expected to be widely recognized on pike-dev -- though DFSG was specific enough for at least me to recognize it as "the Debian Free Software Guidelines".

Just a little reminder...

Everywhere! :-)