Cost classification Within the costing system of a manufacturing company the following types of expense are incurred. Reference number: 1 Cost of oils used to lubricate production machinery 2 Motor vehicle licences for lorries 3 Depreciation of factory plant and equipment 4 Cost of chemicals used in the laboratory 5 Commission paid to sales representatives 6 Salary of the secretary to the finance director 7 Trade discount given to customers 8 Holiday pay of machine operatives 9 Salary of security guard in raw material warehouse 10 Fees to advertising agency 11 Rent of finished goods warehouse 12 Salary of scientist in laboratory 13 Insurance of the company's premises 14 Salary of supervisor working in the factory 15 Cost of typewriter ribbons in the general office 16 Protective clothing for machine operatives