UNIX trademark registration

[chongo at nsc.uucp]

In article <1213 at orca.UUCP> andrew at orca.UUCP (Andrew Klossner) writes:
 >In the U.S., trademark protection is completely independent from
 >copyright protection.  And, in fact, the AT&T Un*x (ed: name modified)
 >system is not protected by copyright in the U.S.; trade secret
 >protection is used instead.

Perhaps someone could explain some things I don't understand:

I do not fully understand how AT&T is able to hold nearly all UN*X systems
as a trade secret.  Is there some kind of a limit on how wide spread
their 'trade secret' can be extended?  Is there some method which
a trade secret becomes so widely known that it is no longer secret?
(much like a trademark can become public domain via too much generic use)

How is AT&T able to claim trade secret over something like 4.2BSD?
	Save your flames about it being based on early Bell Labs systems, and
	save your flames about how any AT&T people who may have helped out,
	and save your flames about the legal papers under which BSD was started.
If you diff 4.2BSD source with V.2 source, you will find that
a great deal of the code is not the same.  Also BSD got major
funding via DARPA, who is in turn funded by US tax payers.
Is there some point where the long arm of trade secret breaks?
Does who did the work and paid for it impact the status of another
person's trade secret claim?  If you start out with a trade secret
code and hack it up one side and down the other while the original
code goes off in another direction, can you claim your own trade secret?

Disclaimer:  The above are my own questions and comments and do not
	     reflect a stand of the company I work for.

chongo <UN*X is a secret kept by tens of thousands of people, at least> /\??/\
-- 
    "Don't blame me, I voted for Mondale!"
				John Alton 85'