 The strategies of fusion and product for combining modal logics rely in merging both the languages and the semantic models of the modal logics to be combined. In the  fibring  strategy (called fibring by functions in Carnielli, Coniglio, et al. 2008), the languages are also merged, but the semantic models remain separated. Formulas can be evaluated in pointed models of any of the original systems, in the following way. When the modality to be semantically evaluated ‘matches’ the chosen semantic model, the evaluation is done as in the original system; when the modality comes from the other system, the fibring strategy uses a transfer mapping to obtain a model and an evaluation point in the class of models for the modality under evaluation, and then the evaluation proceeds as in the original system. Thus, modal fibring requires a correspondence between the class of models of each one of the systems, and uses it to move between them when the modality under evaluation requires it.