Properly maximal points in product spaces

We study maximal points in a locally convex space partially ordered by a convex cone with a bounded base. Properly maximal points are defined and compared with other concepts of efficiency. Existence and density theorems are given which unify and generalize several results known in recent literature. Particular attention is paid on properly maximal points in a product space which has an interesting application in obtaining a multiplier rule for convex set-valued problems in a general setting.