FIFO COSTING under manufacturing concern

Sir, my question is related to FIFO costing. FIFO is very easy to understand under trading concern. But i have problems under manufacturing concern. My understanding is that under manufacturing concern FIFO means that Goods manufatured first are sold first. But if we made cost of goods manufactured statement like this :- Opening Raw material Add: purchases Less:closing raw material Equals raw material consumed Add: opening Work in process Less:closing Work in process Equals cost of goods manufactured Add opening Finished Goods Less closing Finished Goods Equals cost of goods sold My question is that if FIFO costing is in operation then whether we apply FIFO only on finished goods stage, that is Goods manufatured first are sold first OR we should also apply it at work in process (just like as we do in process costing) stage and raw material stage (earliest purchased raw material is taken to the process earlier)