  The state λ is typically thought of as the pair's state at the emission time, and it is assumed that this state does not change in any relevant sense between the emission and the first measurement. It is (generally) a different state from the quantum-mechanical pair's state ψ. ψ is assumed to be an incomplete state of the pair, whereas λ is supposed to be a (more) complete state of the pair. Accordingly, pairs with the same state ψ may have different states λ which give rise to different probabilities of outcomes for the same type of measurements. Also, the states λ may be unknown, hidden, inaccessible or uncontrollable.