Once again, it has reared it's ugly head about NOSA, GPL, LGPS and licensing in general.  It has been popular on Wikipedia's World Wind entry as seen on the talk page and it came up again on the past few days on the mailing list.

Patrick Hogan has stepped up and posted this to the mailing list as an explanation to the licensing and how they all interact:

Dear Open Source Community, World Wind Development Community, and
Entrepreneurial Enterprise Community, or any combination thereof,

Rather than try to decipher each of the issues expressed regarding the World
Wind (WW) license, it should be clearly stated that NASA World Wind.NET and
NASA World Wind Java, under the NASA Open Source Agreement (NOSA) license,
allow for anyone to make 'changes to the core' and redistribute. This 'core'
will necessarily fall under the NOSA. But, this *does not restrict* the
ability for third-parties to combine the World Wind core with their
proprietary extensions or applications that leverage this core.

Core refers to the NASA World Wind source code released publicly. Any change
to the publicly released source code, i.e., World Wind core, constitutes a
change that falls under the NOSA.

Unlike the GPL the NOSA does not seek to define any encumbrances other than
that changes to the core go into the public core. These terms are even less
restrictive than the GPL.

Allowed Core Change: You wish to embed or extend NASA World Wind and
commercially distribute this 'package.' This might involve some changes to
the core to optimize that use. The code changes made to the World Wind core
would fall under the NOSA, but this does not in any way apply to the rest of
any software 'package' external to the World Wind core as it might be
embedded or extended.

Not-Allowed Core Change: The NOSA does restrict 'locking-up' the World Wind
core, i.e., making changes to the core and then distributing that core as a
proprietary application. Any code placed into the World Wind core must
always remain accessible (open source) and non-proprietary per the NOSA.

Allowed Use of World Wind: The NOSA license encourages evolution of the code
base. The NOSA also encourages commercial use by allowing for the core
(i.e., World Wind SDK) to be embedded into other proprietary applications or
extended with proprietary modules. The value of this World Wind SDK will
increase as the open source community helps to evolve the World Wind core to
better serve geospatial visualization needs. These needs can certainly be
proprietary as when World Wind is extended or embedded with *separate*
modules or applications.

Again, any extended or embedded modules or applications *external* to the
World Wind core, even though they may have dependencies on the World Wind
core, can be intellectual property and are free to be commercially marketed,
even as a package distributed with changes to the World Wind SDK (core).
Only the changes to the World Wind core fall under the NOSA. So, repeating
now for emphasis, the World Wind core is free to be 'packaged' by third
parties with proprietary modules or proprietary applications. Distribution
of this 'package' commercially or otherwise, only requires that changes to
the World Wind core must necessarily remain under the NOSA license.

We invite the community to support NASA in evolving the core so that it
better serves the geospatial visualization needs of any enterprise.