This paper deals with the treatment of the international linkages and the relationships between foreign flows and interregional ones, in a context of a biregional input-output model, which will be built within the Tuscany case study.
In the first part of the paper, different approaches are surveyed with reference to some existing models including I/O matrices, even if they were not designed at a biregional level.
The second part of the paper aims at describing the approach we have followed in designing the model for the Tuscany region with respect to the international trade components
