DISregard for a moment that IRAF seems to include code from a nonfree yacc.
IRAF has a kind of custom government license which was previously decided [0] to be free. IRAF wants to link with NCAR which is (now) available under the GPL. Is that allowed, even though IRAF is not GPL? IRAF is not a "derivitive" of NCAR, although the resulting executable binaries would be, I guess. GPL seems to say so: These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. [...] If that is the case, then it seems that I should consider creating a complementary NCAR package ("when you distribute them as separate works"), on which IRAF would have build and runtime dependencies (I don't know if the upstream NCAR build intends for the libraries to be shared .so files, or if they even intend for the libraries to be installed on a runtime-only system, but no matter). Justin References [0] http://lists.debian.org/debian-legal/2004/05/msg00338.html