the licence

[forsyth@plan9.cs.york.ac.uk forsyth@plan9.cs.york.ac.uk]

>>Generous I think might be stretching it. Although I meant this as a
>>joke, the agreement *could* be onerous.

the transitive closure clause seems generous to me; i'd not previously
seen anything like it in a licence agreement for commercial software.
indeed, i was astonished when i first read it.

the agreement is written (and this goes beyond discerning `intent', it's in the text) so
as to ensure that anything new you write remains yours, but anything they
wrote doesn't become yours (and even then, there's protection for you
if you have to adhere to a system interface that means your code invariably
looks like some of their code elsewhere that also adheres to that interface).

for instance, my Oberon front end is mine, mine, all mine.  sod off.
if, however, i build code generators for it by copy & change of
the Plan 9 C or Alef code generators, i can't claim the latter as mine even if
i tinker with them.  if, however, i write from scratch a whizzy instruction
scheduler to go with it, and change their code to call my scheduler, they
don't acquire my scheduler.

having ownership be determined on whether your code is
``derived from [AT&T] code (in the copyright sense)''
seems equitable to me.