TGrid - which computes transmission tariffs for generation and load using any of several methods, including the Nodal scheme currently employed in the UK, Colombia and Brazil; the Average Participation Scheme used by Peru and by the Central American Regional Market and proposed for the European Union; the Aumann-Shapley scheme now being considered for Brazil. TGrid has been used in Latin America and China, by investors projecting their transmission tariffs and by regulators and government agencies evaluating the characteristics of different transmission pricing schemes.