"FIFO" stands for first-in, first-out, meaning that the oldest inventory items are recorded as sold/used first.
In order to counter food waste, hospitality businesses make use of the FIFO-principle. New items are put in the back of the stock, so the products that are about to expire first are used first as well.
APICBASE uses this principle as well. If you have products with different pack sizes, different suppliers, different prices and you're wondering how APICBASE will deal with this... The answer is FIFO. Products that are delivered first, will be sold and used first.