🚀 go-pugleaf

>>Let us take the possibility that you have a source license to a product
>>(i.e. ATT UNIX).  You are free to make improvements.  Your code can
>                                                       ^^^^^^^^^^^^^
>>be under any license you choose.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>If I modify GNU code, and decide to give it to someone, my modifications
>_can't_ be under any license I choose; they must be under the GNU license.

Not entirely true.  Ghostscript is being distributed both under GPL
as well as a standard commercial license.  This, however, is entirely
beside the point.

>>Remember, however, that in order to
>>be useful to anyone, a person using your code must have access to
>>UNIX source (if he doesn't, then you didn't need the source either.  An
>>example is someone who writes a spreadsheet).  Thus, a prerequisite for
>>your licensee is a UNIX source license.  Thus, effectively ATT propagates
>>their license.  Is this any different from GPL?
>
>Yes.  The AT&T "propagation" only spreads to AT&T code.  If I had code of my
>own, added it to AT&T source, and gave it to someone else who also had a source
>license, that person could cut out my added code and use it for whatever he
>wishes without propagating the AT&T license.  If I did the same to GNU source,
>the license would be propagated.

Yes but AT&T's is effectively being propagated.  If I wrote an improvement
to the UNIX filesystem or memory management and wanted to distribute it 
out, it would only be useful to those with UNIX source licenses.  A person 
who wanted to use my improvements (and didn't have a UNIX source license) 
would have to obtain one before being able to use my improvements.  In
effect, then, AT&T is propagating their license.  My improvements are
meaningless without access to UNIX source.  Similarly, if I make an
improvement to GCC, this improvement is meaningless without access to 
GCC source.  Following in Ghostscript's footsteps, I may release my code 
under any license I wish but without access to GCC source, these 
improvements are meaningless.  While AT&T propagates their license 
unofficially (de facto), GPL makes it part of their license (de jure).  
Effectively, then, there is little difference.  

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