Plan 9 encumbrance

[Dave Mason dmason@plg.uwaterloo.ca]

dmr@plan9.att.com writes:
> The terms of the new Plan 9 distribution will be much more liberal
[... and look completely reasonable ]

> By contrast, Unix source licenses were and are fearsome documents,
> with references to trade-secret "methods and concepts" and
> restrictions on use even for educational purposes.
> 
> Fundamentally, USL sued BSDI and then UC Berkeley for producing
> a Unix clone (and lost).  BSDI and UCB's CSRG thought this
> was a worthwhile thing to do because the real thing was overpriced
> and hard to get.  Plan 9 will be cheap and easy to get.
> Situations change, and we learn.

My question is: If I get and read and enjoy your distribution, and
then decide I want to write a commercial equivalent of some part of
Plan 9 (say my own implementation of Alef to run under Windows-NT --
don't worry, I already went and washed my mouth out), what will AT&T
and/or its lawyers say about it?  Or I think I see how to build the
kernel better?  As an OS researcher, this is a *very* relevant
question for me.  While the USL silliness was going on I was thanking
my lucky stars that I'd never looked at any Unix system code.

What about the authors of vsta (a plan-9 inspired system about to
release version 1.4)?  Must they *not* look at the plan-9 code?  They
currently don't use exactly the message format that plan-9
does... what if they change to use the right one?

Very much looking forward to the release... if I can look at it.
../Dave