This paper contains a description of the production and labour demand sections of the BOF4 model. CES value added production functions are developed and estimated for the five sectors of the economy. From these the marginal product of labour and capital functions are derived which are important factors in determining investments and the prices of gross outputs in each of the sectors. The demand for labour hours is defined as a gradual adjustment process towards the level determined by the inverted production' functions. An input-output model is used to determine output and value-added deflators by sectors as well as the prices of the different demand components.