The new legislation about the planning of urban territories allows private parties to exchange between them rights of building on a land. In order to create a proper market, such agreements shall be registered, even when a right of building is transferred to a party who is merely interested in re-sailing it, since he or she is not actually owner of a land of his or her own and is therefore not entitled to exercise the acquired right. The nature and content ofbthese juridical positions are therefore highly disputed.