Product_column.offStruct      = FIELDOFFSET (PRODUCTRECORD, Product_name);
Gross_income_column.offStruct = FIELDOFFSET (PRODUCTRECORD, Gross_income);
Net_income_column.offStruct   = FIELDOFFSET (PRODUCTRECORD, Net_income);
Total_cost_column.offStruct   = FIELDOFFSET (PRODUCTRECORD, Total_cost);
