  In this paper we define the Radon-Nikodym class (RN class) of locally convex
topological vector spaces. The RN class is characterized in terms of the
Radon-Nikodym theorem for vector measures using integrable by seminorm
derivatives. It is shown that the RNP class of all complete Hausdorff locally
convex spaces possessing the Radon-Nikodym property is properly contained in
the RN class. As an application we present a Radon-Nikodym theorem for
multimeasures with respect to the Pettis integrable multifunctions in terms of
the RN class.
