The Soviet economy was brought to balance by the interlocking of three sets of calculation, namely the setting up of a model incorporating balances of production, manpower and finance. The exercise was undertaken annually and involved a process of iteration (the "method of successive approximation").[58] Although nominally a "centrally planned" economy, in reality formulation of the plan took place on a more local level of the production process as information was relayed from enterprises to planning ministries. Aside from the USSR and Eastern bloc economies, this economic model was also utilized by the People's Republic of China, Socialist Republic of Vietnam, Republic of Cuba and North Korea.