 The interpretation of these relations has often been debated. Do Heisenberg’s relations express restrictions on the experiments we can perform on quantum systems, and, therefore, restrictions on the information we can gather about such systems; or do they express restrictions on the meaning of the concepts we use to describe quantum systems? Or else, are they restrictions of an ontological nature, i.e., do they assert that a quantum system simply does not possess a definite value for its position and momentum at the same time? The difference between these interpretations is partly reflected in the various names by which the relations are known, e.g., as “inaccuracy relations”, or: “uncertainty”, “indeterminacy” or “unsharpness relations”. The debate between these views has been addressed by many authors, but it has never been settled completely. Let it suffice here to make only two general observations.