I couldn't see any reason why David would object to my remailing this
to the list; I presuem he was just saving bandwidth; but here's a
reference that says that even _NetSol_, wearing their InterNIC hat,
said that .org was for non-profits:
-----Forwarded message from David Schiffrin <daves@adnc.com>-----
This doesn't fit *my* recollection either, but here's a ref:
http://rs.internic.net/glossary/#o
and a qoute:
org
The top level domain designated for miscellaneous entities that do not
fit under any of the other top level domains. Typically used for
non-profit organizations. One of the worldwide top level domains.
[see also: Top Level Domain]
This *is* from a current page, and I have no idea when or how this definition
may have changed over time, but it does seem to be currently accurate.
I understand that this doesn't address the question directly, which
has to do with historical inentions, but it's all I could find in
five minutes of poking about..
Wait a minute.... There is value in never deleting anything 
A domain registration template dated 7/95 reads as follows:
in "Section 2 - Complete Domain Name"
EDU is for 4-year, degree granting institutions.
GOV is for United States federal government agencies.
COM is for commercial, for-profit organizations.
NET is for network infrastructure machines and organizations.
ORG is for not-for-profit and non-profit organizations.
This is a historical reference. I can forward the entire text of a
"Version Number: 1.0" domain-template if you'd like.
-dave
-----End of forwarded message-----
I suspect that's about as authoritative as we're going to get, for now.
Cheers,
-- jra