 As Bub (1997) points out (see Section 2), in most modal interpretations the preferred context of definite-valued observables is determined solely by the dynamical state of the system; but one could also introduce a preferred definite-valued observable. An example is Bohmian mechanics, in which the preferred context is a priori defined by the position observable; in this case, property composition and property decomposition hold. But this is not the only reasonable possibility for a modal interpretation with a fixed preferred observable. In fact, the modal-Hamiltonian interpretation (MHI, Lombardi and Castagnino 2008) endows the Hamiltonian of a system with a determining role, both in the definition of systems and subsystems and in the selection of the preferred context.