OTOH, Mr. Licensing (AKA, Brett Smith) has said that they are incompatible,
so you cannot mix them up in the same program.What Brett has said as far as I've seen is that GPLv2 and GPLv3 are incompatible, but "GPLv2 or later" code can be distributed (as GPLv3) with GPLv3 (or later) code. It is the distributions without the "or later" that are problematic. Anyway, I will work on making the updates in gnulib.
