for example, if the customer in position 5 offers to exchange places with anyone in positions 20-30, and a customer in position 29 offers to exchange places with anyone in positions 1-10, then the system will automatically exchange their positions. it lets you comparison shop airport parking lots, and find & reserve a space for almost always less than the drive-up price. the true point is that sally and don now share a secret. try to build flexibility into your lease in case it takes longer than you thought it would to start bringing in paying customers. 