Q: What exactly are the said modifications to the original framework?
A:
Q: Are there any legal implications upon the source framework?
A: While the author (Shaun Mitchell) and the publisher (Packt Publishing) have kindly granted permission for modifying, extending and re-using the framework on "as is" basis, you need to take into account the SDL's license (currently, zlib) as well as the fact that the non-code assets must be obtained through legal means; none of the image or sound files will ever be provided in the codeplex package, so acquiring them is up to you. Essentially, you need to distribute your source code along with the applications that are using sdl2fwk. Let others learn from your experience!