Incompatibilites in Concurrent Programs

I have a question. In incompatibilites, you have the option in the scope statement of set or program. I thought SET was only for request sets, but the more I am reading, it looks like if a concurrent program launches children out of itself, that you would want to use the SET instead of PROGRAM for that concurrent program. That might solve some of the issues with ATP/MRP, if that is true. Is the above true?

Scope
Enter Set or Program Only to specify whether your concurrent program is incompatible with this program and all its child requests (Set) or only with this program (Program Only).