 This bilattice is equipped with two partial orderings; in addition to a truth order, there is an information order \((\le_i )\) which is said to order the values under consideration according to the information they give concerning a formula to which they are assigned. Lattice meet and join with respect to \(\le_t\) coincide with the functions \(f_{\wedge}\) and \(f_{\vee}\) in the Belnap matrix \(\mathbf{B}_4\), \(f_{{\sim}}\) turns out to be the truth order inversion, and an entailment relation, which happens to coincide with the matrix entailment, is defined by  (8).  FOUR\(_2\) arises as a combination of two structures: the approximation lattice \(A_4\) and the logical lattice \(L_4\) which are discussed in Belnap 1977a and 1977b (see also, Anderson, Belnap and Dunn 1992: 510–518)).