R1) Liberty. The physicist is free to employ as many frameworks as desired when constructing descriptions of a particular quantum system, provided the principle R3 below is strictly observed. (R2) Equality. No framework is more fundamental than any other; in particular, there is no “true” framework, no framework that is “singled out by nature”. (R3) Incompatibility. The single framework rule: incompatible frameworks are never to be combined into a single quantum description. The (probabilistic) reasoning process starting from assumptions (or data) and leading to conclusions must be carried out using a single framework. (R4) Utility. Some frameworks are more useful than others for answering particular questions about a quantum system.