Its use in the warehouse
FIFO prevents goods from aging on the rack when the product has no expiration date but is subject to obsolescence, packaging changes or version changes. In accounting, FIFO also names an inventory valuation method; in the warehouse it describes only the physical outbound order.
How Chainlink WMS applies it
The difference with FEFO appears when a new lot expires before an old one: FIFO picks the old lot and FEFO the one that expires first. In Chainlink WMS, each warehouse uses FEFO or FIFO as its allocation strategy; with FIFO, the system allocates the stock received first.