[belorn]

Programs written in C is a bit more obvious in how tightly coupled a program is to their libraries. It takes quite a lot of intention, work and design to make a C program independent of their library dependencies. If you remove a library and the work is completely inoperative and will practically never function without reapply the library, then the legal argument that they are independent and separate works start to loose strength.

For programs written in interpreted languages, it is a bit less obvious how tightly coupled a program is to their libraries. It depend a lot on the design, intended use and the environment. Some programs regardless of language is going to be heavy dependent and based on a specific library, rather than a generic API for which any library could implement. The more the program incorporates aspects of the library as part of the program, the stronger the argument is for derivative status.