See the {Fidonet} entry
IBM
International Business Machines
MIT
Massachusetts Institute of Technology; esp. the legendary MIT AI Lab
culture of roughly 1971 to 1983 and its feeder groups, including the
Tech Model Railroad Club
NRL
Naval Research Laboratories
NYU
New York University
OED
The Oxford English Dictionary
Purdue
Purdue University
SAIL
Stanford Artificial Intelligence Laboratory (at Stanford
University)
SI
From Syst`eme International, the name for the standard
conventions of metric nomenclature used in the sciences
Stanford
Stanford University
Sun
Sun Microsystems
TMRC
Some MITisms go back as far as the Tech Model Railroad Club (TMRC) at
MIT c. 1960. Material marked TMRC is from `An Abridged Dictionary
of the TMRC Language', originally compiled by Pete Samson in 1959
UCLA