Abstract. In this paper we establish the existence of relative weight filtrations of cones of monodromy logarithms and identities between relative weight filtrations in a context more general than M. Kashiwaras infinitesimal mixed Hodge modules. This generalizes a theorem of M. Kashiwara and adds conceptual clarity to the problem. Our approach to working with relative weight filtrations is to split the weight filtrations with canonical splittings introduced by P. Deligne. These splittings agree with the splittings that occur in the -theory of variations of pure Hodge structure of W. Schmid and of E. Cattani, A. Kaplan, and W. Schmid, but are more general, as they dont require filtrations to be monodromy weight filtrations.