Just had a look at RFC-1, my first look ever. First thing I noticed is
the enormous amount of abbreviations one is assumed to be able to
instantly place :-)
So looking up IMP for instance the wiki page gives me this funny titbit
"When Massachusetts Senator Edward Kennedy learned of BBN's
accomplishment in signing this million-dollar agreement, he sent a
telegram congratulating the company for being contracted to build the
"Interfaith Message Processor"."
https://en.wikipedia.org/wiki/Interface_Message_Processor