but without knowing the odds of getting the jackpot, there is no rational way to differentiate. In many markets where central monitoring and control systems are used to link machines for auditing and security purposes, usually in wide area networks of multiple venues and thousands of machines, player return must usually be changed from a central computer rather than at each machine. A range of percentages is set in the game software and selected remotely. In 2006, the Nevada Gaming Commission began working with Las Vegas casinos on technology that would allow the casino's management to change the game, the odds, and the payouts remotely. The change cannot be done instantaneously, but only after the selected machine has been idle for at least four minutes. After the change is made, the machine must be locked to new players for four minutes and display an on-screen message informing potential players that a change is being made. Linked machines Some varieties of slot machines can be linked together in a setup sometimes known as a "community" game. The most basic form of this setup involves progressive jackpots that are shared between the bank of machines, but may include multiplayer bonuses and other features. In some cases multiple machines are linked across multiple casinos. In these cases, the machines may be owned by the manufacturer, who is responsible for paying the jackpot. The casinos lease the machines rather than owning them outright. Casinos in New Jersey, Nevada, Louisiana, Arkansas, and South Dakota now offer multi-state progressive jackpots, which now offer bigger jackpot pools. Fraud Mechanical slot machines and their coin acceptors were sometimes susceptible to cheating devices and other scams. One historical example involved spinning a coin with a short length of plastic wire. The weight and size of the coin would be accepted by the machine and credits would be granted. However, the spin created by the plastic wire would cause the coin to exit through the reject chute into the payout tray. This particular scam has become obsolete due to improvements in newer slot machines. Another obsolete method of defeating slot machines was to use a light source to confuse the optical sensor used to count coins during payout. Modern slot machines are controlled by EPROM computer chips and, in large casinos, coin acceptors have become obsolete in favor of bill acceptors. These machines and their bill acceptors are designed with