[em-bee]

some developers who use GPL licenses interpret these requirements differently and permit certain uses that the FSF does not. A notable example is the Linux kernel, which allows proprietary kernel modules under specific conditions.

this is not necessarily a different interpretation of the license but it is an exception the authors make. and they can do that because they are the authors.

the interesting question is if they could change their mind and remove the exception. i believe they could. should they though? that's another question altogether.