While safety and security at a high-level are white-board concepts, once it comes to implementation in a MILS core (separation kernel + minimal set of additional hardware and software needed for the separation of partitions), sometimes the concrete realization depends on what is doable. Several use cases of partitioning are mapped to partitioning mechanisms implementing the partitioning. The main idea is that this paper takes "safety" + "something" and calls it "security". The main result is that different use cases of safety and security can be compared, and one can precisely talk about differences. If one is aware of differences, one can strive for and maintain strong notions of safety and security.