Defining what is Quantum: Not all what matters for physical phenomena is contained in space-time

Abstract: It is argued that the three main quantum interpretations, Copenhagen, de Broglie-Bohm, and Many-Worlds, support the Principle Q (Quantum): Not all what matters for physical phenomena is contained in space-time. This principle underpins Born's rule as well. So Principle Q may be the best way to defining Quantum "from more fundamental principles".