Cities take delivery of the fuel you sell them
When you sell Jet Fuel or Marine Fuel into a city airport's or seaport's standing bid, the city now ships it to its tank on its next restock, instead of leaving it at the exchange and buying the same fuel again.
A city airport or seaport that cannot find fuel for sale posts a standing bid on the exchange, marked System in the order book. Until now, when you sold into one, the city paid for the fuel but never shipped it: it sat at the exchange as Ready for pickup, and the city went on to buy the same amount again elsewhere.
A city now books delivery of a filled bid before it buys anything else, so your sale refuels the airport or port that asked for it. Fuel already sold into these bids will be delivered as well.
Gasoline sold to transport companies and supplies sold to public-works builders are used straight from the exchange, so those sales now complete at once instead of staying Ready for pickup.