Profit On Resale.
POR stated on a product in a wholesaler is the amount or profit a business owner can make by selling a product at its recommended retail price. Of course, a shopkeeper (for instance) can make more profit on an item (provided they can still sell it, of course) by charging a higher price, and it is for this reason that un-price-marked-packs are often more expensive.
POR can also be calculated for the catering industry, coming from the cost of all the comprising ingredients in a certain menu item. It often appears to be much higher than the POR of a retail product, however it does not account for the required labour and skill to turn raw ingredients into a sale-able meal.