Possibly OT: Splitting Hairs Over GPL?

[Michael Torrie]

On 04/07/2010 11:28 AM, Dave Smith wrote:
> Sounds like software vendors can release software licensed under GPL 
> plus their own terms (e.g., no command-line invoking), or does the GPL 
> disallow this?

If a company owns the copyright on their code they can release it under
any terms they desire.  Using the GPL as a license plus extra
terms/restrictions, provided that the wording you use in your license
isn't contradictory, is completely acceptable.

The most famous example of using the GPL plus extra terms is the GNU
libc library.  I believe it's GPL with the exception that binaries of
any license can link against it (since it's a system library).  The
linux kernel also has a modified GPL license.  I believe the terms "GPL
v2 or greater" is removed from its license.