An order-theoretic
characterization of the topology of compact convergence on the lattice C(X) of all
continuous real-valued functions on X is provided for a realcompact space X,
analogous to the order unit characterization for compact X. The approach is to
generalize the concept of an order unit to permit consideration of locally
convex topologies. The characterization is then achieved by viewing C(X) as a
subspace of its order bidual. In addition, the bidual is employed to provide
an order-theoretic description of the continuous convergence structure on
C(X).