3. The deductible costs for works referred to in paragraphs a and b of section 1 are:(a) where the operator carries out works on his own account: the direct costs of material, labour, maintenance of equipment, additives, supervision, surveying for holes for diamond drilling and the direct costs of labour, maintenance of equipment and supervision for geological and geophysical works;
(b) where the operator subcontracts works: the overall costs the subcontractor charges to the operator.