Given a pure quantum state | ψ ψ ⟩ ⟩ , Born's rule tells that the probability to obtain another state | ϕ ϕ ⟩ ⟩ in a measurement is | ⟨ ⟨ ϕ ϕ | ψ ψ ⟩ ⟩ | 2 . However, such a number does not define a full probability distribution, i.e. values over a set of mutually exclusive events, summing up to 1. In order to obtain such a set one needs to specify a context, that is a complete set of commuting operators (CSCO), or equivalently a set of N orthogonal projectors | ϕ ϕ n ⟩ ⟩ ⟨ ⟨ ϕ ϕ n | that sum to identity, where N is the dimension of the Hilbert space. Then one has ∑ ∑ n | ⟨ ⟨ ϕ ϕ n | ψ ψ ⟩ ⟩ | 2 = 1 as expected. In that sense, one can tell that a state vector | ψ ψ ⟩ ⟩ alone is predictively incomplete, as long a context has not been specified. The actual physical state, now defined by | ϕ ϕ n ⟩ ⟩ within a specified context, has been called a modality by Auffèves and Grangier