mulle-core provides functionality that is outside of the C standard libraries. These libraries are not strictly concerned with concurrency like mulle-concurrent is, but may use features of mulle-concurrent. So mulle-core*is a grabbag of libraries, that is set to grow and that might get reorganized into more topical library collections later on.
mulle-core is based on mulle-concurrent and mulle-c.
The MulleFoundation is based on mulle-core.